CARRIER1 INTERNATIONAL S A
S-4/A, 1999-06-24
COMMUNICATIONS SERVICES, NEC
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<PAGE>

     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JUNE 24, 1999

                                                      REGISTRATION NO. 333-75195
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                            ------------------------


                                AMENDMENT NO. 3
                                       TO
                                    FORM S-4
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933

                            ------------------------

                          CARRIER1 INTERNATIONAL S.A.
             (Exact name of Registrant as specified in its charter)

<TABLE>
<S>                                       <C>                                       <C>
               LUXEMBOURG                                   4813                                   98-0199626
    (State or other jurisdiction of             (Primary Standard Industrial                    (I.R.S. Employer
     incorporation or organization)             Classification Code Number)                   Identification No.)
</TABLE>

                            ------------------------

                                ROUTE D'ARLON 3
                          L-8009 STRASSEN, LUXEMBOURG
                             (011) (41-1) 297-2600

              (Address, including ZIP code, and telephone number,
       including area code, of Registrant's principal executive offices)
                         ------------------------------

                                 KEES VAN OPHEM
                  VICE PRESIDENT, PURCHASE AND GENERAL COUNSEL
                          CARRIER1 INTERNATIONAL GMBH
                               MILITARSTRASSE 36
                          CH-8004 ZURICH, SWITZERLAND
                             (011) (41-1) 297-2600

           (Name, address, including ZIP code, and telephone number,
            including area code, of Registrant's agent for service)
                         ------------------------------

                                 WITH COPY TO:
                           DAVID A. BRITTENHAM, ESQ.
                              DEBEVOISE & PLIMPTON
                                875 THIRD AVENUE
                            NEW YORK, NEW YORK 10022
                                 (212) 909-6000

    APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: As soon as
practicable after this Registration Statement becomes effective.

    If the securities being registered on this Form are being offered in
connection with the formation of a holding company and there is compliance with
General Instruction G, check the following box. / /

    If this form is filed to register additional securities of an offering
pursuant to Rule 462(b) under the Securities Act, check the following box and
list the Securities Act registration statement number of the earlier effective
registration statement for the same offering. / /

    If this form is a post-effective amendment filed pursuant to Rule 462(d)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /
                         ------------------------------

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
                                                                         PROPOSED MAXIMUM
                                                                             OFFERING            PROPOSED           AMOUNT OF
               TITLE OF EACH CLASS                     AMOUNT TO BE         PRICE PER       MAXIMUM AGGREGATE      REGISTRATION
          OF SECURITIES TO BE REGISTERED                REGISTERED         SECURITY(1)      OFFERING PRICE(1)         FEE(3)
<S>                                                 <C>                 <C>                 <C>                 <C>
13 1/4% Senior Dollar Notes Due 2009..............     $160,000,000            100%            $160,000,000         $44,480.00
                                                     [Euro]85,000,000
13 1/4% Senior Euro Notes Due 2009................   ($92,803,000)(2)          100%            $92,803,000          $25,800.00
</TABLE>

(1) Estimated solely for the purpose of calculating the registration fee in
    accordance with Rule 457 promulgated under the Securities Act of 1933, as
    amended.

(2) Euro amounts have been translated into U.S. Dollars at [Euro]1=$1.0918,
    which was the noon buying rate in New York City for cable transfers in Euro
    as certified for customs purposes by the Federal Reserve Bank of New York on
    March 23, 1999.

(3) Paid with the initial filing of the Registration Statement.
                         ------------------------------

    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT OF 1933 OR UNTIL THIS REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(A),
MAY DETERMINE.

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>

                   SUBJECT TO COMPLETION, DATED JUNE 24, 1999

THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY
NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER
TO SELL THESE SECURITIES AND IT IS NOT SOLICITING AN OFFER TO BUY THESE
SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.
<PAGE>
PROSPECTUS


                       OFFER TO EXCHANGE ALL OUTSTANDING
                    13 1/4% SENIOR DOLLAR NOTES DUE 2009 AND
                       13 1/4% SENIOR EURO NOTES DUE 2009


                                 FOR REGISTERED
                    13 1/4% SENIOR DOLLAR NOTES DUE 2009 AND
                       13 1/4% SENIOR EURO NOTES DUE 2009



                          CARRIER1 INTERNATIONAL S.A.


THE NEW NOTES:


    - The terms of the new notes are identical to the terms of the relevant old
      notes except that the new notes are registered under the Securities Act of
      1933 and will not contain restrictions on transfer or provisions relating
      to additional interest and will contain different administrative terms.



    INVESTING IN THE NEW NOTES INVOLVES RISKS. YOU SHOULD CAREFULLY REVIEW THE
RISK FACTORS BEGINNING ON PAGE 12 OF THIS PROSPECTUS.


THE EXCHANGE OFFER:


    - Our offer to exchange old notes for new notes will be open until 5:00
      p.m., New York City time, on         , 1999, unless we extend the offer
      with respect to one or both series.



    - No public market currently exists for the notes.


    NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE
ADEQUACY OR ACCURACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

                 The date of this prospectus is         , 1999
<PAGE>
                               TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                                                                                                PAGE
                                                                                                                -----
<S>                                                                                                          <C>
Certain Regulatory Issues..................................................................................           3
Presentation of Financial Information......................................................................           4
Summary....................................................................................................           5
Risk Factors...............................................................................................          12
Where You Can Find More Information........................................................................          23
The Exchange Offer.........................................................................................          24
Use of Proceeds............................................................................................          32
Dividend Policy............................................................................................          33
Capitalization.............................................................................................          34
Unaudited Pro Forma Consolidated Financial Information.....................................................          35
Selected Consolidated Financial Data.......................................................................          38
Management's Discussion and Analysis of Financial Condition and Results of Operations......................          40
Business...................................................................................................          49
Management.................................................................................................          76
Certain Relationships and Related Transactions.............................................................          84
Principal Security Holders.................................................................................          87
Description of the Notes...................................................................................          89
Taxation...................................................................................................         135
Plan of Distribution.......................................................................................         139
Legal Matters..............................................................................................         139
Experts....................................................................................................         139
Index to Consolidated Financial Statements.................................................................         F-1
</TABLE>


                            ------------------------


    The indentures pursuant to which the notes are issued require us to
distribute to the holders of the notes annual reports containing our financial
statements audited by our independent auditors and quarterly reports containing
unaudited condensed consolidated financial statements for the first three
quarters of each fiscal year. When we refer to "Carrier1 International," we are
referring to the holding company Carrier1 International S.A., the issuer of the
notes. When we refer to ourselves generally or to "Carrier1," we are referring
to Carrier1 International and its subsidiaries and their predecessors, except
where the context otherwise requires.



    WE HAVE NOT AUTHORIZED ANYONE TO GIVE YOU ANY INFORMATION OR TO MAKE ANY
REPRESENTATIONS ABOUT THE TRANSACTIONS WE DISCUSS IN THIS PROSPECTUS OTHER THAN
THOSE CONTAINED HEREIN. IF YOU ARE GIVEN ANY INFORMATION OR REPRESENTATIONS
ABOUT THESE MATTERS THAT IS NOT DISCUSSED, YOU MUST NOT RELY ON THAT
INFORMATION. THIS PROSPECTUS IS NOT AN OFFER TO SELL OR A SOLICITATION OF AN
OFFER TO BUY SECURITIES ANYWHERE OR TO ANYONE WHERE OR TO WHOM WE ARE NOT
PERMITTED TO OFFER OR SELL SECURITIES UNDER APPLICABLE LAW. THE DELIVERY OF THIS
PROSPECTUS OR THE NOTES OFFERED HEREBY DOES NOT, UNDER ANY CIRCUMSTANCES, MEAN
THAT THERE HAS NOT BEEN A CHANGE IN OUR AFFAIRS SINCE THE DATE HEREOF. IT ALSO
DOES NOT MEAN THAT THE INFORMATION IN THIS PROSPECTUS IS CORRECT AFTER THIS
DATE.


                           CERTAIN REGULATORY ISSUES


    Persons in the United Kingdom will be eligible to receive new notes to be
issued in this exchange offer only if the ordinary activities of such persons
involve them in acquiring, holding, managing or disposing of investments (as
principal or agent) for the purposes of their businesses or otherwise in
circumstances which do not constitute an offer to the public in the United
Kingdom for purposes of the U.K. Public Offers of Securities Regulation 1995.


    This prospectus is being distributed on the basis that each person in the
United Kingdom to whom this prospectus is issued is reasonably believed to be a
person falling within an exemption to section 57 of the

                                       3
<PAGE>
Financial Services Act 1986, as amended, as set out in the Financial Services
Act 1986 (Investment Advertisements) (Exemptions) Order 1996 (as amended by the
Financial Services Act 1986 (Investment Advertisements) (Exemptions) Order 1997)
and, accordingly, by accepting delivery of this prospectus the recipient
warrants and acknowledges that it is a person falling within any such exemption.

                     PRESENTATION OF FINANCIAL INFORMATION

    We report our financial statements in U.S. dollars and prepare our financial
statements in accordance with generally accepted accounting principles in the
United States. Carrier1 has adopted a fiscal year end of December 31.

    In this prospectus, except where otherwise indicated, references to

       (1) "$" or "U.S. dollars" are to the lawful currency of the United
       States,

       (2) "[Euro]" or "Euro" are to the single currency at the start of the
       third stage of European economic and monetary union on January 1, 1999,
       pursuant to the treaty establishing the European Economic Community, as
       amended by the treaty on European Union, signed at Maastricht on February
       7, 1992, and

       (3) "DM" are to the lawful currency of Germany.

    Given its recent introduction, there is insufficient historical exchange
rate data concerning the Euro for inclusion in this prospectus. The ECU,
predecessor to the Euro, is a composite currency, consisting of specified
amounts of currencies of certain European Union member states. The ECU basket is
composed of specified amounts of the German mark, the British pound sterling,
the French franc, the Italian lira, the Dutch guilder, the Belgian franc, the
Luxembourg franc, the Danish kroner, the Irish punt, the Greek drachma, the
Spanish peseta and the Portuguese escudo. Changes in exchange rates of the
currencies of the member states of these European Communities, including
revaluations and devaluations, do not affect the fixed composition of the ECU
but may change the exchange rate of the ECU in subsequent trading.


    Stage III of the European Economic and Monetary Union began on January 1,
1999, and on that date the value of the ECU as against the currencies of the
member states participating in Stage III was irrevocably fixed and the ECU
became a currency in its own right. On June 17, 1997, the Council of the
European Union adopted Council Regulation (European Communities) No. 1103/97,
establishing the Euro and providing for the substitution of the Euro for the ECU
at the rate of one Euro for one ECU. On January 1, 1999, 11 of the 15 member
countries of the European Union established fixed conversion rates between their
then existing sovereign currencies and the Euro and adopted the Euro as their
common legal currency on that date. These legacy currencies are scheduled to
remain legal tender in the participating countries as denominations of the Euro
until January 1, 2002. During the transition period, public and private parties
may pay for goods and services using either the Euro or the participating
countries' legacy currency.


                                       4
<PAGE>
                                    SUMMARY

    YOU SHOULD READ THE FOLLOWING SUMMARY TOGETHER WITH THE MORE DETAILED
INFORMATION REGARDING OUR COMPANY, THE SECURITIES BEING SOLD AND OUR
CONSOLIDATED FINANCIAL STATEMENTS AND THE NOTES THERETO APPEARING ELSEWHERE IN
THIS PROSPECTUS.


                                    CARRIER1



    Carrier1 is a rapidly expanding European facilities-based provider of long
distance voice and Internet Protocol data telecommunications services. We offer
these services on a wholesale basis primarily to competitive fixed-line
operators, other carriers, wireless operators, ISPs, resellers and
multi-national corporations. In March 1998, our experienced management team and
Providence Equity Partners formed Carrier1 to capitalize on the significant
voice and data opportunities that are emerging for facilities-based carriers in
Europe's rapidly liberalizing telecommunications markets. By September 1998, we
had deployed our initial network and commenced selling wholesale services. As of
December 31, 1998, we had executed 48 contracts with voice customers and 17
contracts with data customers. As of March 31, 1999, we had executed an
additional 31 contracts with voice customers and an additional 18 contracts with
data customers.


    We are developing an extensive city-to-city European network linking key
population centers. We intend to continue rapidly expanding this network in a
cost-effective manner to serve the needs of our existing and potential
customers.


    To rapidly deploy our network and offer services we are initially leasing
our European transmission capacity. However, we have entered into a development
agreement to build a 2,300 kilometer fiber network in Germany with Viatel Inc.
and Metromedia Fiber Network, Inc. This network will connect 14 principal cities
and pass a number of other major cities. It will also provide fiber capacity in
regions we believe are not covered or are underserved by existing and announced
fiber networks. The important advantages of the German Network are direct
ownership, cost reduction, and flexibility.


EQUITY SPONSORS


    Funds managed by Providence Equity Partners Inc. and Primus Venture
Partners, Inc. have invested $60 million to finance the deployment of our
network and to fund start-up operations. The final installment of this
investment was made at the time of the offering of the old notes. After giving
effect to this investment, the Providence funds indirectly hold approximately
71%, and the Primus funds indirectly hold approximately 14%, of the common stock
of Carrier1 International, on a fully diluted basis. Providence is a private
investment firm that specializes in equity investments in telecommunications and
media companies in the United States and abroad. Primus is a private investment
firm that focuses on equity investments in telecommunications and other
high-technology industries.


                                  *    *    *

    Carrier1 International is a holding company and renders its services
indirectly through subsidiaries primarily located in various Western European
countries. Its registered office is located at L-8009, Strassen, Route d'Arlon
3, Luxembourg. Executive offices of Carrier1 International GmbH, its principal
management services subsidiary, are located at Militarstrasse 36, CH-8004
Zurich, Switzerland. Its phone number is 011-41-1-297-2600.

                                       5
<PAGE>
                   SUMMARY OF THE TERMS OF THE EXCHANGE OFFER


    On February 19, 1999, we completed a private offering of (a) 160,000 Dollar
Units, each consisting of one 13 1/4% Senior Dollar Note due 2009 and one
warrant to purchase shares of common stock and (b) 85,000 Euro Units, each
consisting of one 13 1/4% Senior Euro Note due 2009 and one warrant to purchase
shares of common stock.



    In this prospectus, we refer to (1) the dollar notes and the Euro notes sold
in the original offering as the old notes, (2) the dollar notes and the Euro
notes offered hereby in exchange for old notes as the new notes, and (3) the old
notes and the new notes together as notes.



<TABLE>
<S>                            <C>
The Exchange Offer...........  You may exchange old dollar notes for new dollar notes and
                               old Euro notes for new Euro notes.

Resale of New Notes..........  We believe the new notes that will be issued in this
                               exchange offer may be resold by most investors without
                               compliance with the registration and prospectus delivery
                               provisions of the Securities Act, subject to certain
                               conditions. You should read the discussion under the heading
                               "The Exchange Offer" for further information regarding the
                               exchange offer and resale of the new notes.

Registration Rights
  Agreement..................  We entered into a registration rights agreement with the
                               initial purchasers of the old notes requiring us to use our
                               best efforts to make this exchange offer. See "Description
                               of the Notes-- Registration Rights."

Consequence of Failure to
  Exchange Old Notes.........  You will continue to hold old notes that remain subject to
                               their existing transfer restrictions if

                               - you do not tender your old notes or

                               - you tender your old notes and they are not accepted for
                                 exchange.

                               Subject to certain limited exceptions, we will have no
                               obligation to register the old notes after we consummate the
                               exchange offer. See "The Exchange Offer--Terms of the
                               Exchange Offer" and "--Consequences of Failure to Exchange."

Expiration Date..............  The exchange offer will expire at 5:00 p.m., New York City
                               time, on             , 1999, unless we extend it, in which
                               case "expiration date" means the latest date and time to
                               which the exchange offer is extended.

Interest on the New Notes....  The new notes will accrue interest at a rate of 13 1/4% per
                               annum from February 19, 1999, the issue date of the old
                               notes, or from the most recent date to which interest has
                               been paid or provided for on the old notes. No additional
                               interest will be paid on old notes tendered and accepted for
                               exchange.

Condition to the Exchange
  Offer......................  The exchange offer is subject to certain customary
                               conditions, which we may waive. See "The Exchange
                               Offer--Conditions."

Procedures for Tendering Old
  Notes......................  If you wish to accept the exchange offer, you must submit
                               required documentation and effect a tender of old notes
                               pursuant to the procedures for book-entry transfer (or other
                               applicable procedures), all in accordance with the
                               instructions described in this prospectus and in the
                               relevant letter of transmittal. See "The Exchange Offer--
</TABLE>


                                       6
<PAGE>


<TABLE>
<S>                            <C>
                               Procedures for Tendering," "--Book-Entry Transfer," and
                               "--Guaranteed Delivery Procedures." Other procedures may
                               apply with respect to book-entry transfers. See "The
                               Exchange Offer--Exchanging Book-Entry Notes."

Guaranteed Delivery
  Procedures.................  If you wish to tender your old notes, but cannot properly do
                               so prior to the expiration date, you may tender your old
                               notes according to the guaranteed delivery procedures set
                               forth in "The Exchange Offer-- Guaranteed Delivery
                               Procedures."

Withdrawal Rights............  Tenders of old notes may be withdrawn at any time prior to
                               5:00 p.m., New York City time, on the expiration date. To
                               withdraw a tender of old notes, a written or facsimile
                               transmission notice of withdrawal must be received by the
                               exchange agent at its address set forth herein under "The
                               Exchange Offer--Exchange Agent" prior to 5:00 p.m., New York
                               City time, on the expiration date.

Acceptance of Old Notes and
  Delivery of New Notes......  Subject to certain conditions, any and all old notes that
                               are validly tendered in the exchange offer prior to 5:00
                               p.m., New York City time, on the expiration date will be
                               accepted for exchange. The new notes issued pursuant to the
                               exchange offer will be delivered as soon as practicable
                               following the expiration date. See "The Exchange Offer--
                               Terms of the Exchange Offer."

Certain U.S. Tax
  Consequences...............  We believe that the exchange of old notes for new notes will
                               not constitute a taxable exchange for U.S. federal income
                               tax purposes. See "Taxation."

Exchange Agent...............  The Chase Manhattan Bank is serving as exchange agent.
</TABLE>


                                       7
<PAGE>

<TABLE>
<S>                            <C>
                           SUMMARY OF THE TERMS OF THE NEW NOTES
</TABLE>


    The terms of the new notes are identical to the terms of the relevant series
of old notes EXCEPT that the new notes:


    - are registered under the Securities Act, and therefore will not contain
      restrictions on transfer,


    - will not contain provisions relating to additional interest, and



    - will contain terms of an administrative nature that differ from those of
      the old notes.



<TABLE>
<S>                            <C>
Maturity.....................  February 15, 2009.

Interest.....................  Interest will be payable in cash on February 15 and August
                               15 of each year, beginning August 15, 1999.

Optional Redemption..........  We may redeem any of the notes beginning on February 15,
                               2004 at the declining redemption prices described in
                               "Description of the Notes--Optional Redemption."

                               In addition, before February 15, 2002, we may redeem up to
                               35% of the aggregate amount of either series of notes with
                               the proceeds of sales of certain kinds of our capital stock
                               at 113.25% of their principal amount.

Additional Amounts...........  All payments on the notes will be made without withholding
                               or deduction for taxes unless required by law. If required
                               by law, we will pay, subject to certain exceptions, the
                               additional amounts necessary so that the net amount received
                               by holders will not be less than the amount that they would
                               have received in the absence of any withholding or
                               deduction.

Tax Redemption...............  In the event that we are obligated to pay any additional
                               amounts as a result of certain changes affecting withholding
                               tax laws and cannot reasonably arrange, without other
                               material adverse consequences to us, for another obligor to
                               make such payment to avoid paying such additional amounts,
                               then we may redeem all the notes at 100% of their principal
                               amount, plus accrued interest.

Security.....................  We have purchased portfolios of government securities and
                               pledged them for the benefit of the holders of the relevant
                               series of notes to secure and fund the first five interest
                               payments on such notes.

Change of Control............  Upon a change of control we will be required to make an
                               offer to purchase the notes. The definition of "change of
                               control" appears under "Description of the Notes". The
                               purchase price will equal 101% of their principal amount
                               plus accrued interest. We may not have sufficient funds
                               available at the time of any change of control to make any
                               required debt payment, including repurchases of the notes.

Ranking......................  The notes will rank equally with all Carrier1
                               International's other unsubordinated unsecured indebtedness
                               and will be junior to all Carrier1 International's secured
                               indebtedness except as described above under "--Security".
                               The notes also will be junior to all liabilities of Carrier1
                               International's subsidiaries. As of March 31, 1999, Carrier1
                               International had no indebtedness outstanding other than the
                               notes and had current liabilities of $4.2 million. As of
                               March 31, 1999 Carrier1 International's subsidiaries had
                               $47.1 million of current liabilities. See our consolidated
                               balance sheet included elsewhere in this prospectus.
</TABLE>


                                       8
<PAGE>


<TABLE>
<S>                            <C>
Certain Covenants............  The terms of the notes will restrict our ability to:

                                   - incur additional indebtedness,

                                   - create liens,

                                   - engage in sale-leaseback transactions,

                                   - pay dividends or make distributions in respect of
                                   capital stock,

                                   - redeem capital stock,

                                   - make investments or certain other restricted payments,

                                   - sell assets,

                                   - issue or sell stock of restricted subsidiaries,

                                   - enter into transactions with stockholders or
                                     affiliates, or

                                   - effect a consolidation or merger.

                               These limitations are subject to a number of important
                               qualifications and exceptions. These limitations,
                               qualifications and exceptions are described in detail under
                               "Description of the Notes."
</TABLE>


                                  RISK FACTORS


    See "Risk Factors," immediately following this Summary, for a discussion of
certain factors relating to us, our business and an investment in the notes.


                                       9
<PAGE>
                      SUMMARY CONSOLIDATED FINANCIAL DATA

    The following table sets forth summary consolidated financial data of
Carrier1 as of and for the period from February 20, 1998 ("Inception") to
December 31, 1998 and as of and for the three months ended March 31, 1999. The
summary consolidated financial data as of and for the period from Inception to
December 31, 1998, were derived from the consolidated financial statements of
the Company which were audited by Deloitte & Touche Experta AG, independent
auditors. The summary consolidated financial data as of and for the three months
ended March 31, 1999, were derived from the unaudited consolidated financial
statements of Carrier1 and include, in the opinion of Carrier1's management, all
adjustments, consisting solely of normal recurring adjustments, necessary to
present fairly the data for such period. The information set forth below is not
necessarily indicative of the results of future operations and should be read in
conjunction with the consolidated financial statements and the related notes
thereto included elsewhere in this Prospectus and "Management's Discussion and
Analysis of Financial Condition and Results of Operations."

    Amounts are presented in thousands, except per share data.


<TABLE>
<CAPTION>
                                                                                     THREE MONTHS    INCEPTION TO
                                                                                        ENDED        DECEMBER 31,
                                                                                    MARCH 31, 1999       1998
                                                                                   ----------------  ------------
<S>                                                                                <C>               <C>
CONSOLIDATED STATEMENTS OF OPERATIONS DATA:
Revenues.........................................................................     $   12,293      $    2,792
Cost of services.................................................................         17,015          11,669
Selling, general and administrative expenses.....................................          3,318           8,977
Depreciation and amortization....................................................          1,336           1,409
                                                                                        --------     ------------
Loss from operations.............................................................         (9,376)        (19,263)
Other income (expense):
Interest income..................................................................            979              92
Interest expense.................................................................         (4,205)            (11)
Currency exchange loss, net......................................................         (2,428)            (53)
                                                                                        --------     ------------
Loss before income tax benefit...................................................        (15,030)        (19,235)
Income tax benefit, net of valuation allowance...................................             --              --
                                                                                        --------     ------------
Net loss.........................................................................     $  (15,030)     $  (19,235)
                                                                                        --------     ------------
                                                                                        --------     ------------
Net loss per share (basic).......................................................     $    (0.53)     $    (2.61)
Net loss per share (diluted)(1)..................................................          (0.53)          (2.61)

OTHER FINANCIAL DATA:
EBITDA (as defined)(2)...........................................................     $   (8,040)     $  (17,854)
Capital expenditures(3)..........................................................         11,609          37,168
Ratio of earnings to fixed charges(4)............................................             --              --
Net cash used in operating activities............................................        (18,910)        (14,441)
Net cash used in investing activities............................................       (152,722)        (19,866)
Net cash provided by financing activities........................................        274,141          37,770
</TABLE>


                                       10
<PAGE>

<TABLE>
<CAPTION>
                                                                     AS OF MARCH 31,      AS OF DECEMBER 31,
                                                                          1999                   1998
                                                                   -------------------  ----------------------
<S>                                                                <C>                  <C>
BALANCE SHEET DATA:
Cash and cash equivalents........................................      $   107,960(5)         $    4,184
Restricted cash..................................................            1,446                 1,518
Restricted investments (6).......................................          143,034(5)                 --
Total assets (7).................................................          329,777                51,434
Total debt.......................................................          249,608(5)                 --
Shareholders' equity.............................................           28,875                19,189
</TABLE>

- ------------------------

(1) Potential dilutive securities have been excluded from the computation for
    the period from Inception to December 31, 1998 and for the three months
    ended March 31, 1999, as their effect is antidilutive.


(2) EBITDA stands for earnings before interest, taxes, depreciation,
    amortization and foreign currency exchange gains or losses.



    EBITDA is used by management and certain investors as an indicator of a
    company's historical ability to service debt. Management believes that an
    increase in EBITDA is an indicator of our improved ability to service
    existing debt, to sustain potential future increases in debt and to satisfy
    capital requirements. However, EBITDA is not a measure of financial
    performance under generally accepted accounting principles and should not be
    considered as an alternative to cash flows from operating, investing or
    financing activities as a measure of liquidity or an alternative to net
    income as indications of Carrier1's operating performance or any other
    measure of performance derived under generally accepted accounting
    principles. EBITDA as presented may not be comparable to other similarly
    titled measures of other companies or to Consolidated EBITDA as calculated
    under the indentures pursuant to which the notes are issued.


(3) Consists of purchases of property and equipment and investment in joint
    venture.

(4) The ratio of earnings to fixed charges is calculated as the sum of income
    before taxes plus interest expense divided by fixed charges. Fixed charges
    consist of the total of (i) interest, whether expensed or capitalized, (ii)
    amortization of debt expense and discount or premium relating to any
    indebtedness, whether expensed or capitalized and (iii) that portion of
    rental expense considered to represent interest costs. Earnings were
    insufficient to cover fixed charges by $15.2 million in the three-month
    period ended March 31, 1999, and by $19.5 million in the period from
    Inception to December 31, 1998.

(5) Assuming the March 31, 1999 conversion rate of Euro into U.S. dollars of
    [Euro]0.92515 per $1.00.

(6) Reflects:


    (a) the portion of the net proceeds for the original offering used to
       purchase government securities to secure and fund the first five
       scheduled interest payments on the notes, see "Description of the
       Notes--Security," and


    (b) approximately $64.8 million used to collateralize a 109.5 million
       Deutsche Mark letter of credit. See the Notes to Unaudited Consolidated
       Financial Statements, Note 5, presented elsewhere in this prospectus.

(7) Includes capitalized financing costs of approximately $7.9 million as of
    March 31, 1999.

                                       11
<PAGE>
                                  RISK FACTORS

    YOU SHOULD CONSIDER CAREFULLY THE RISKS DESCRIBED BELOW AND OTHER
INFORMATION IN THIS PROSPECTUS BEFORE MAKING AN INVESTMENT DECISION.


    IF ANY OF THE FOLLOWING RISKS ACTUALLY OCCUR, OUR BUSINESS, FINANCIAL
CONDITION, RESULTS OF OPERATIONS OR ABILITY TO PAY PRINCIPAL OR INTEREST ON THE
NOTES COULD BE MATERIALLY ADVERSELY AFFECTED. IN THAT EVENT, YOU MAY LOSE ALL OR
PART OF YOUR INVESTMENT.



IF YOU DO NOT PROPERLY TENDER YOUR OLD NOTES, YOU WILL CONTINUE TO HOLD
  UNREGISTERED OLD NOTES AND YOUR ABILITY TO TRANSFER OLD NOTES WILL BE
  ADVERSELY AFFECTED.



    We will only issue new notes in exchange for old notes that are timely and
properly tendered. Therefore, you should allow sufficient time to ensure timely
delivery of the old notes and you should carefully follow the instructions on
how to tender your old notes. Neither we nor the exchange agent are required to
tell you of any defects or irregularities with respect to your tender of the old
notes. If you do not exchange your old notes for new notes pursuant to the
exchange offer, the old notes you hold will continue to be subject to the
existing transfer restrictions. In general, the old notes may not be offered or
sold, unless registered under the Securities Act, or exempt from registration
under the Securities Act and applicable state securities laws. We do not
anticipate that we will register old notes under the Securities Act.



    After the exchange offer is consummated, if you continue to hold any old
notes of either series, you may have trouble selling them because there will be
fewer old notes of such series outstanding. In addition, if a large number of
old notes of either series are not tendered or are tendered improperly, the
limited amount of new notes of such series that would be issued and outstanding
after we consummate the exchange offer could lower the market price of such new
notes.


OUR LIMITED OPERATING HISTORY MAKES IT DIFFICULT FOR YOU TO EVALUATE OUR
  PERFORMANCE.

    We formed our business in March 1998, and we commenced commercial operations
on September 1, 1998. Accordingly, you have limited historical operating and
financial information on which to base your evaluation of our performance.

WE EXPECT TO EXPERIENCE NET LOSSES AND NEGATIVE CASH FLOW.


    Our continued business development and network deployment will require that
we incur substantial capital expenditures. In general, we expect to incur net
losses and negative cash flow from operating activities through 2000. Whether or
when we will generate positive cash flow from operating activities will depend
on a number of financial, competitive, regulatory, technical and other factors,
many of which are beyond our control. See "Management's Discussion and Analysis
of Financial Condition and Results of Operations--Liquidity and Capital
Resources." We cannot assure you that we will achieve profitability or positive
cash flow.


OUR OPERATING RESULTS MAY FLUCTUATE SIGNIFICANTLY.

    At least initially, our revenues are dependent upon a relatively small
number of customers and contracts. The loss or addition of one or more customers
or contracts could cause significant fluctuations in our financial performance.
In addition, the significant expenses resulting from the expansion of our
network and services are likely to lead to operating results that vary
significantly from quarter to quarter.

                                       12
<PAGE>
OUR ABILITY TO GENERATE CASH TO SERVICE OUR SUBSTANTIAL CAPITAL NEEDS DEPENDS ON
  MANY FACTORS, SOME OF WHICH ARE BEYOND OUR CONTROL.


    We will require significant capital to fund our capital expenditures and
working capital needs, as well as our debt service requirements and cash flow
deficits.



    We expect to incur significant capital expenditures in connection with the
expansion of our network. The actual amounts and timing of our future capital
requirements may vary significantly from our estimates. The demand for our
services, regulatory developments and the competitive environment of the
telecommunications industry could cause our capital needs to exceed our current
expectations. In that case, we may need to seek additional capital sooner than
we expect, and such additional financing may not be available on acceptable
terms or at all. Moreover, our substantial indebtedness as a result of the
original offering and other possible future debt financings may adversely affect
our ability to raise additional funds. A lack of financing may require us to
delay or abandon plans for deploying parts of our network.



OUR SUBSTANTIAL INDEBTEDNESS AND OUR ABILITY TO INCUR MORE INDEBTEDNESS COULD
  PREVENT US FROM FULFILLING OUR OBLIGATIONS UNDER THE NOTES.


    We have significant indebtedness. The following table shows certain
important credit statistics.

<TABLE>
<CAPTION>
                                                                                                        MARCH 31,
                                                                                                          1999
                                                                                                      -------------
<S>                                                                                                   <C>
                                                                                                      (IN MILLIONS)
Total debt..........................................................................................    $   249.6
Shareholders' equity................................................................................         28.9
Total debt as a percentage of total capitalization..................................................           90%
</TABLE>

    Our deficiency of earnings to fixed charges for the three-month period ended
March 31, 1999 was $15.2 million.


    The indentures pursuant to which the notes are issued limit, but do not
prohibit, our incurrence of additional indebtedness. Moreover, the indentures
permit us to incur an unlimited amount of indebtedness to finance the
acquisition of equipment, inventory and network assets. A substantial level of
debt may make it more difficult for us to repay you.



    If we cannot generate sufficient cash flow from operations to meet our debt
service requirements, we may be required to refinance our indebtedness,
including the notes. Our ability to obtain such financing will depend on our
financial condition at the time, the restrictions in the agreements governing
our indebtedness and other factors, including general market and economic
conditions. If such refinancing were not possible, we could be forced to dispose
of assets at unfavorable prices. In addition, we could default on our debt
obligations, including our obligation to make payments on the notes.


OUR DEBT AGREEMENTS IMPOSE OPERATING AND FINANCIAL RESTRICTIONS, WHICH MAY
  PREVENT US FROM CAPITALIZING ON BUSINESS OPPORTUNITIES.


    The indentures pursuant to which the notes are issued impose significant
operating and financial restrictions on us. The terms of any other financings we
may obtain may do so as well. These restrictions may substantially limit or
prohibit us from taking various actions including incurring additional debt,
making investments, paying dividends to our shareholders, creating liens,
selling assets, engaging in mergers and consolidations, repurchasing or
redeeming capital stock and capitalizing on business opportunities.



    Failure to comply with the covenants and restrictions in the indentures or
other financing agreements could trigger defaults under such agreements even if
we are able to pay our debt. Such defaults could result in a default on the
notes and could delay or preclude payment of principal of or interest on the
notes.


                                       13
<PAGE>

IF WE ARE UNABLE TO EXTEND OUR NETWORK IN THE MANNER WE HAVE PLANNED, OUR
  OPERATING REVENUES OR GROSS MARGINS COULD BE ADVERSELY AFFECTED.



    Our success will depend on our ability to continue to deploy our network on
a timely basis. We have contracted with Nortel Plc for the installation of our
switch system and with Cisco Systems International, B.V. for the installation of
our router system. A failure by either of these parties to continue to comply
with its contractual obligations could cause delays in the continued deployment
of our network.



    A number of other factors could hinder the deployment of our network. These
factors include cost overruns, the unavailability of additional capital,
strikes, shortages, delays in obtaining governmental or other third-party
approvals, natural disasters and other casualties, and other events that we
cannot foresee.


    Delays in the continued deployment of our network could:

    - limit the geographic scope of our services,

    - prevent us from providing services on a cost-effective basis,

    - reduce the number of customers we can attract and the volume of traffic we
      carry,

    - force us to rely more heavily on refiling or reselling for terminating our
      traffic, increasing termination costs and making our quality control more
      difficult, and

    - affect our ability to obtain lower cost capacity on other networks by
      swapping excess capacity.

    Any one of these results could lower our operating revenues or adversely
impact gross margins.


WE HAVE NO CONTROL OVER THIRD PARTIES ON WHOM WE RELY FOR THE OPERATION OR
  MAINTENANCE OF PORTIONS OF OUR NETWORK, AND IF THEY OR THEIR FACILITIES DO NOT
  PERFORM OR FUNCTION ADEQUATELY, OUR NETWORK MAY BE IMPAIRED.



    Our success is dependent on the technical operation of our network and on
the management of traffic volumes and route selections over the network. We have
outsourced the technical operation and management of our voice network to
Nortel. If Nortel fails to perform these functions adequately or in a timely
manner, our network and our operations could be materially adversely affected.
Furthermore, we are dependent on parties from whom we have leased or acquired a
right to use transmission capacity for maintenance of certain of the network's
circuits. Shortfalls in maintenance by any of these parties could lead to
transmission failure. Our network is also subject to other risks outside our
control, such as the risk of damage from fire, power loss, natural disasters and
general transmission failures caused by these or other factors.



    We intend to take over the full operation of our network by mid-1999. We may
not be able to operate and manage our network adequately once the turnkey
contracts have been terminated.



WE ARE DEPENDENT ON OUR HIGHLY TRAINED EXECUTIVE OFFICERS AND EMPLOYEES. ANY
  DIFFICULTY IN MAINTAINING OUR CURRENT EMPLOYEES OR IN HIRING SIMILAR EMPLOYEES
  WOULD ADVERSELY AFFECT OUR ABILITY TO OPERATE OUR BUSINESS.


    Our operations are managed by a small number of key executive officers,
including our Chief Executive Officer, Stig Johansson. The loss of any of these
individuals could have a material adverse effect on us. In addition, our success
depends on our ability to continue to attract, recruit and retain sufficient
qualified personnel as we grow. Competition for qualified personnel in Europe is
intense, and there is generally a limited number of persons with the requisite
experience in the sectors in which we operate. We cannot assure you that we will
be able to retain senior management, integrate new managers or recruit qualified
personnel in the future.

                                       14
<PAGE>

A FAILURE TO ENTER INTO OR MAINTAIN ADEQUATE INTERCONNECTION AND PEERING
  ARRANGEMENTS COULD CAUSE US TO INCUR HIGHER TERMINATION COSTS THAN COMPETITORS
  WHO HAVE SUCH ARRANGEMENTS.



    The most cost-effective way for a wholesale carrier to achieve termination
in a country in which it has a point of presence is to negotiate an
interconnection agreement with the national incumbent telephone operator.
Failure to implement adequate interconnection arrangements would cause us to
incur high termination costs, which could have a material adverse effect on our
ability to compete with carriers that do have interconnection agreements.



    Our ability to obtain peering arrangements with European and United States
ISPs will also affect our costs. To the extent we do not have peering
arrangements, we are required to pay a transit fee in order to exchange data
traffic. Our inability to obtain sufficient peering arrangements would keep our
data termination costs high and could limit our ability to compete effectively
with other European Internet backbone providers that have more peering
arrangements than we do.



    See "Management's Discussion and Analysis of Financial Condition and Results
of Operations-- Factors Affecting Future Operations--Cost of Services--Voice
Termination Costs"; "--Data Termination Costs."


IF WE LOST ONE OR MORE OF OUR GOVERNMENT LICENSES OR BECAME SUBJECT TO MORE
  ONEROUS GOVERNMENT REGULATIONS, WE COULD BE ADVERSELY AFFECTED.


    We are subject to varying degrees of regulation in each of the jurisdictions
in which we provide services. Local laws and regulations, and their
interpretation differ significantly among those jurisdictions. Future
regulatory, judicial and legislative changes may have a material adverse effect
on the operation of our business.


    National regulatory frameworks that are fully consistent with the policies
and requirements of the European Commission and the World Trade Organization
have only recently been, or are still being, put in place in many European Union
member states. These nations are in the early stages of providing for and
adapting to a liberalized telecommunications market. As a result, in these
markets, we and other new entrants may encounter more protracted and difficult
procedures to obtain licenses and negotiate interconnection agreements.


    Our operations are dependent on licenses that we acquire from governmental
authorities in each jurisdiction in which we operate. These licenses and
authorizations generally contain clauses pursuant to which we may be fined or
our license may be revoked in certain circumstances. Such revocation may be on
short notice, at times as short as 30 days' written notice to us. The revocation
of any of our licenses would force us to stop operating in the relevant country.



IF WE DO NOT SUCCESSFULLY COMPETE WITHIN THE HIGHLY COMPETITIVE
  TELECOMMUNICATIONS INDUSTRY, WE MAY BE UNABLE TO REPAY THE NOTES.


    The European telecommunications market is highly competitive, and
liberalization is rendering it increasingly more so. The opening of the market
to new service providers, combined with technological advances, has resulted in
significant reductions in retail and wholesale prices for voice services. We
expect prices to continue to decline. Decreasing prices are also narrowing gross
profit margins on long distance voice traffic. Our ability to compete
successfully in this environment will significantly depend on our ability to
generate high traffic volumes from our customers while keeping our costs of
services low. We cannot assure you that we will be able to do so.


    We expect price decreases in the European data market over the next few
years as competition increases. We cannot assure you that data service prices
will not decline more quickly than our data transmission or termination costs,
which could have a material adverse effect on our gross profit margins and our
ability to repay the notes.


                                       15
<PAGE>
    Other competitive factors include the following:

    - Certain voice customers may redirect their traffic to another carrier on
      the basis of even small differences in price.

    - Wholesale carriers that have built their network may lower prices so as to
      increase volume and maximize utilization rates.

    - Excess capacity being built could create further downward pressure on
      prices.


    See "Business--Competition."



OUR COMPETITORS MAY HAVE MORE EXPERIENCE, SUPERIOR OPERATIONAL ECONOMIES OR
  GREATER RESOURCES, PLACING US AT A COST AND PRICE DISADVANTAGE.



    We compete with a number of incumbent telephone operators, who generally
control access to local networks and have significant operational economies,
including large national networks, and existing operating agreements with other
incumbents. Moreover, national regulatory authorities have, in some instances,
shown reluctance to adopt policies that would result in increased competition
for the local incumbent. In addition, incumbents may be more likely to provide
transmission capacity on favorable terms and direct excess traffic to their
related carriers than to us.



    In data services, our main competitors have an established customer base and
either a significant infrastructure or strong connectivity to the United States
through various peering arrangements. We believe that, if the quality of the
service is consistently high, data customers will typically renew their
contracts because it is costly and technically burdensome to switch carriers,
which could impede our ability to attract new customers.



    We also compete with companies that have announced that they are building
European networks to the extent these companies offer wholesale services. Some
of these companies have more experience operating a network than Carrier1 does.
We may not be able to deploy a European network as quickly or run it as
efficiently as some or all of these competitors, which could impair our ability
to compete with them.



    Many of our competitors have greater financial resources and would be in a
better position than we would be to withstand the adverse effect on gross profit
margins caused by price decreases, particularly those competitors that already
own infrastructure and have interconnection or peering arrangements and thus
enjoy a lower cost base than we do. Unless and until we are able to reduce our
cost base, we may not be able to compete on the basis of price if market prices
are reduced below a certain level. Inability to price services competitively may
in turn cause us to lose customers.



WE MAY NOT BE ABLE TO OBTAIN SUFFICIENT COST-EFFECTIVE TRANSMISSION CAPACITY,
  WHICH COULD DELAY OUR ABILITY TO PENETRATE CERTAIN MARKETS OR CARRY A HIGHER
  VOLUME OF TRAFFIC IN MARKETS IN WHICH WE ALREADY OPERATE.


    We lease or have purchased rights to use our current transmission capacity
from others, and we therefore depend on them for much of our transmission
capacity. We believe that there is a shortage in the supply of cost-effective
transmission capacity. We cannot assure you that we will always be able to
obtain capacity where and when we need it at an acceptable price or at all. Any
failure to obtain such capacity could delay our ability to penetrate certain
markets or to carry a higher volume of traffic in the markets in which we
already operate. Furthermore, to the extent some of our capacity suppliers begin
to compete with us in the provision of wholesale telecommunications services,
those suppliers may no longer be willing to provide us with capacity.

                                       16
<PAGE>

    Until the German Network is operational, we will need to lease or purchase
additional capacity as we extend our network. It is unlikely that we will be
able to obtain such capacity at our target cost levels. We will therefore, in
the short term, continue to have transmission costs that are higher than our
target cost levels and higher than the costs of our competitors who own
transmission infrastructure. We cannot assure you that the cost of obtaining
capacity will decrease. In addition, if the German Network is not completed on a
timely basis, we will need to rely to a greater extent than currently
anticipated on leased lines. If we cannot obtain rights to use the existing
capacity at our target cost levels for the future capacity we will require
beyond that capacity we own, we will need to build or purchase that additional
capacity. To build additional capacity, we would need to incur additional
capital expenditures. It is also possible that additional capacity would not be
available for purchase at the time that we need it.


IF ESTIMATES WE HAVE MADE ARE NOT CORRECT, WE MAY HAVE TOO MUCH OR TOO LITTLE
  CAPACITY.

    We rely on other carriers to provide certain termination services.
Negotiation of refile or resale agreements with such carriers involves making
estimates of the future calling patterns and traffic levels of our customers.
Underestimation of traffic levels or failure to estimate calling patterns
correctly could lead to:

    - a shortage of capacity, requiring us to either lease more capacity or
      reroute calls to other carriers at a higher termination cost,

    - higher termination costs, as we may have to use additional, higher priced,
      refilers or resellers, and

    - a possibly lower quality of service, as we may not be carrying the traffic
      over our own network.

    Our leased capacity costs are fixed monthly payments based on the capacity
made available to us. If our traffic volumes decrease, or do not grow as
expected, the resulting idle capacity will increase our per unit costs.


WE MAY HAVE DIFFICULTY INTEGRATING OR ENHANCING OUR SOPHISTICATED BILLING,
  CUSTOMER AND INFORMATION SYSTEMS. ANY SUCH DIFFICULTIES COULD DELAY OR DISRUPT
  OUR ABILITY TO SERVICE OR BILL OUR CUSTOMERS.


    Sophisticated information systems are vital to our growth and our ability
to:

    - manage and monitor traffic along our network,

    - track service provisioning, traffic faults and repairs,

    - effect least cost routing,

    - achieve operating efficiencies,

    - monitor costs,

    - bill and receive payments from customers, and

    - reduce credit exposure.

    We have outsourced to International Computers Limited the running of our
billing system program. Errors or problems with International Computers
Limited's computer systems could delay our ability to send bills to our
customers or to provide billing information on-line. We plan to take over the
full operation of our billing system by June 1999. We cannot assure you that
this transition will not cause delays or interruptions in our monitoring and
billing activities.

    The billing and information systems we have acquired will require
enhancements and ongoing investments, particularly as traffic volume increases.
We may encounter difficulties in enhancing our systems or integrating new
technology into our systems in a timely and cost-effective manner. Such
difficulties could have a material adverse effect on our ability to operate
efficiently and to provide adequate customer service.

                                       17
<PAGE>
RAPID CHANGE IN OUR INDUSTRY COULD REQUIRE US TO EXPEND SUBSTANTIAL COSTS TO
  IMPLEMENT NEW TECHNOLOGIES. WE COULD LOSE CUSTOMERS IF OUR COMPETITORS
  IMPLEMENT NEW TECHNOLOGIES BEFORE WE DO.

    The European telecommunications industry is changing rapidly due to, among
other things:

    - market liberalization,

    - significant technological advancements,

    - introductions of new products and services utilizing new technologies,

    - increased availability of transmission capacity,

    - expansion of telecommunications infrastructure, and

    - increased use of the Internet for voice and data transmission.


    If the growth we anticipate in the demand for voice and data services were
not to occur or we were precluded from servicing this demand, we might not be
able to generate sufficient revenues in the next few years to fund our working
capital requirements.


    To compete effectively, we must anticipate and adapt to rapid technological
changes and offer, on a timely basis, competitively priced services that meet
evolving industry standards and customer preferences. We may choose new
technologies that prove to be inadequate or incompatible with technologies of
our customers, providers of transmission capacity or other carriers. As new
technologies develop, we may be forced to implement such new technologies at
substantial cost to remain competitive. In addition, competitors may implement
new technologies before we do, allowing such competitors to provide lower priced
or enhanced services and superior quality compared to those we provide. Such a
development could have a material adverse effect on our ability to compete,
particularly because we seek to distinguish ourselves on the basis of the
quality of our services.


WHOLESALE CUSTOMERS THAT ARE PRICE SENSITIVE MAY DIVERT THEIR TRAFFIC TO ANOTHER
  CARRIER BASED ON SMALL PRICE CHANGES, RESULTING IN FLUCTUATIONS OR LOSS IN OUR
  REVENUE.



    Voice customers often maintain relationships with a number of
telecommunications providers, and our contracts with our wholesale voice
customers generally do not impose on customers minimum or maximum usage
requirements. Furthermore, basic voice services are not highly differentiated.
As a result, most customers are price sensitive and certain customers may divert
their traffic to another carrier based solely on small price changes. These
diversions can result in large and abrupt fluctuations in revenues. The majority
of our data contracts to date have been usage-based, with no minimum volume
commitment by the customer. There can be no assurance that small variations
between our prices and those of other carriers will not cause our voice
customers to divert their traffic.



    Our contracts with our wholesale customers require us to carry their voice
traffic at a contractually fixed price per minute that can only be changed upon
seven or thirty days' notice. Similarly, we have contracted with some data
customers to carry their data traffic at a fixed monthly rate that can only be
changed upon six or twelve months' notice. If we were forced to carry voice or
data traffic over a higher-cost route due to capacity and quality constraints,
our gross profit margins would be reduced.



WE RELY ON A SMALL NUMBER OF SIGNIFICANT CUSTOMERS, AND THE LOSS OF ANY SINGLE
  CUSTOMER COULD THEREFORE HAVE A MATERIAL ADVERSE EFFECT ON OUR REVENUES.



    We currently depend on a small number of significant customers for our
revenues. The loss of any single customer could therefore have a material
adverse effect on us. In addition, certain wholesale customers may be
unprofitable or only marginally profitable, resulting in a higher risk of
delinquency or nonpayment. Recently, the Internet services industry has
experienced increased merger and consolidation


                                       18
<PAGE>

activity among ISPs and Internet backbone providers. The consolidation of ISPs
may reduce the customer base for our data services.


IF WE ARE UNABLE TO IMPROVE AND ADAPT OUR OPERATIONS AND SYSTEMS AS WE GROW, WE
  COULD LOSE CUSTOMERS AND REVENUES.

    We expect our business to continue to grow rapidly, which may significantly
strain our customer support, sales and marketing and administrative resources
and network operation and management and billing systems. Such a strain on our
operational and administrative capabilities could adversely affect the quality
of our services and our ability to collect revenues. To manage our growth
effectively, we will have to further enhance the efficiency of our operational
support and other back office systems, and of our financial systems and
controls. We will also have to expand and train our employee base to handle the
increased volume and complexities of our business. We cannot assure you that we
will maintain adequate internal operating, administrative and financial systems,
procedures and controls, or obtain, train and adequately manage sufficient
personnel to keep pace with our growth.

    In addition, if we fail to project traffic volume and routing preferences
correctly, or to determine the optimal means of expanding the network, we could
lose customers, make inefficient use of the network, and have higher costs and
lower profit margins.


OUR OPERATING COMPANIES HAVE NO OBLIGATION TO MAKE PAYMENTS ON THE NOTES. THEY
  MAY FACE LEGAL OR OTHER LIMITATIONS ON THEIR ABILITY TO MAKE CASH AVAILABLE
  FOR PAYMENT ON THE NOTES.



    Carrier1 International is the company obligated to pay amounts due under the
notes. Carrier1 International is a holding company with few assets of
significance other than the stock of its subsidiaries. Carrier1 International
intends to loan or contribute all or a portion of the proceeds of the original
offering to its subsidiaries. The cash flow and consequent ability of Carrier1
International to service its debt obligations, including the notes, are
dependent upon the ability of Carrier1 International to receive cash from its
subsidiaries. These subsidiaries are separate legal entities and have no
obligations to pay amounts due under the notes or to make funds available for
such payment. In addition, applicable law of the jurisdictions in which these
subsidiaries are organized or contractual or other obligations to which they are
subject may limit their ability to pay dividends or make payments on
intercompany loans, including those made with the proceeds of the original
offering. Furthermore, the payment of interest and principal on intercompany
loans and advances as well as the payment of dividends by these subsidiaries may
be subject to taxes. Claims of creditors of these subsidiaries will generally
have priority as to the assets of such subsidiaries over the claims of the
holders of Carrier1 International's debt, including the notes, except under
certain circumstances to the extent that Carrier1 International is also a
creditor of any subsidiary. Accordingly, the notes will be effectively
subordinated to the liabilities of these subsidiaries.



THE NOTES WILL BE EFFECTIVELY SUBORDINATED TO OUR SECURED DEBT.



    The notes will not be secured by any of our assets except the pledged
securities as described under "Description of the Notes--Security." We expect to
incur future indebtedness which may be secured, particularly through equipment,
network or working capital financings. If we default on our other secured
indebtedness, or in the event of our bankruptcy, liquidation or reorganization,
our assets would be available to pay our obligations on the notes only after we
had made all payments on such secured debt. To the extent that the value of such
assets was insufficient to repay our secured debt, holders of such secured debt
would be entitled to share in any of our remaining assets on parity with you and
other unsecured creditors.


                                       19
<PAGE>
WE WILL ENGAGE IN JOINT VENTURES, WHICH ARE ACCOMPANIED BY INHERENT RISKS.

    We plan to construct the German Network with Viatel and Metromedia. We may
enter into future joint ventures with other companies. All joint ventures are
accompanied by risks. These risks include:

    - the lack of complete control over the relevant project,

    - diversion of our resources and management time,

    - inconsistent economic, business or legal interests or objectives among
      joint venture partners,

    - the possibility that a joint venture partner will default in connection
      with a capital contribution or other obligation, thereby forcing us to
      fulfill such obligation, and

    - difficulty maintaining uniform standards, controls, procedures and
      policies.

WE ARE CONTROLLED BY PARTIES WHOSE INTERESTS MAY NOT BE ALIGNED WITH YOURS.

    Funds managed by Providence and Primus together indirectly hold
approximately 85%, and the Providence funds alone indirectly hold approximately
71%, of the equity of Carrier1 International. Therefore, the Providence funds
alone, and the Providence and Primus funds together, indirectly control us. Such
ownership may present conflicts of interest between the Providence or Primus
funds and you if we encounter financial difficulties or the Providence and
Primus funds cause us to pursue transactions that could enhance their equity
investment while involving risks to your interests.

    Providence and Primus, or their affiliates, currently have significant
investments in other telecommunications companies, including investments by
Providence affiliates in Epoch Networks and Tele1 Europe AB, and may in the
future invest in other entities engaged in the telecommunications business, some
of which may compete with us. Providence and Primus are under no obligation to
bring us any investment or business opportunities of which they are aware, even
if opportunities are within our scope and objectives. Conflicts may also arise
in the negotiation or enforcement of arrangements we may enter into with
entities in which Providence or Primus, or their affiliates, have an interest.

WE MAY BE ADVERSELY AFFECTED BY YEAR 2000 ISSUES.

    Computer programs that have time-sensitive software may recognize a date
using "00" as the year 1900 rather than the year 2000, which could result in
miscalculations or a major system failure. We cannot assure you that all our
systems will then function adequately. A failure of our computer systems or
other systems could have a material adverse effect on us. We are still
evaluating whether the systems of our vendors, suppliers or customers are or
will be Year 2000 compliant. Any failure of their computer systems could
materially and adversely affect our ability to operate our network and retain
customers and could impose significant costs on us. See "Management's Discussion
and Analysis of Financial Condition and Results of Operations--Impact of Year
2000."

CONVERSION TO THE EURO MAY RESULT IN INCREASED COSTS AND POSSIBLE ACCOUNTING,
  BILLING AND LOGISTICAL DIFFICULTIES IN OPERATING OUR BUSINESS.


    From January 1, 1999, until January 1, 2002, the Euro will exist in
electronic form only and the participating countries' individual currencies will
persist in tangible form as legal tender. During the transition period, everyone
must manage transactions in both the Euro and the participating countries'
respective individual currencies. This may cause significant logistical
problems. We may incur increased operational costs and may have to modify or
upgrade our information systems in order to respond to possible accounting,
billing and other logistical problems resulting from the conversion to the Euro.


                                       20
<PAGE>
THE INTERNATIONAL SCOPE OF OUR OPERATIONS MAY ADVERSELY AFFECT OUR BUSINESS.

    We may face certain risks because we conduct an international business
including:

    - regulatory restrictions or prohibitions on the provision of our services,

    - tariffs and other trade barriers,

    - longer payment cycles,

    - problems in collecting accounts receivable,

    - political risks, and

    - potentially adverse tax consequences of operating in multiple
      jurisdictions.

    In addition, an adverse change in laws or administrative practices in
countries within which we operate could have a material adverse effect on us.


    We are exposed to fluctuations in foreign currencies, as our revenues,
costs, assets and liabilities are denominated in multiple local currencies. Our
payment obligations with respect to the notes are denominated in U.S. dollars,
but our revenues are denominated in other currencies as well. Any appreciation
in the value of the U.S. dollar relative to such other currencies could have a
material adverse effect on us.


ENFORCING JUDGMENTS AGAINST US MAY REQUIRE COMPLIANCE WITH NON-U.S. LAW.

    Most assets of Carrier1 International and its subsidiaries are located
outside the United States. You will need to comply with foreign laws to enforce
judgments obtained in a U.S. court against our assets, including to foreclose
upon such assets. In addition, it may not be possible for you to effect service
of process within the United States upon us, or to enforce against us U.S. court
judgments predicated upon U.S. federal securities laws.


THERE WILL BE NO PUBLIC TRADING MARKET FOR THE NEW NOTES.



    The new notes are a new issue of securities with no established trading
market. The new dollar notes will not be listed on any securities exchange.
Although we expect that application will be made to have the new Euro notes
included on the Regulated Unofficial Market (Freiverkehr) of the Frankfurt Stock
Exchange, we cannot assure you that the new Euro notes will be so included. The
liquidity of the trading market in the new notes, and the market price quoted
for the new notes, may be adversely affected by changes in the overall market
for high yield securities and by changes in our financial performance or
prospects or in the prospects for companies in our industry generally. As a
result, you cannot be sure that an active trading market will develop for the
new notes.


EVENTS DESCRIBED BY OUR FORWARD-LOOKING STATEMENTS MAY NOT OCCUR.


    This prospectus includes or incorporates forward-looking statements. We have
based these forward-looking statements on our current expectations and
projections about future events and on industry publications. We have not
independently verified the data derived from industry publications.


    Our forward-looking statements are subject to risks, uncertainties and
assumptions including, among other things, those discussed above as well as
under "Management's Discussion and Analysis of Financial Condition and Results
of Operations." Examples of forward-looking statements include all statements
that are not historical in nature, including statements regarding:

    - operations and prospects,

    - technical capabilities,

                                       21
<PAGE>
    - funding needs and financing sources,

    - network deployment plans,

    - scheduled and future regulatory approvals,

    - expected financial position,

    - business and financial plans,

    - markets, including the future growth in the European telecommunications
      market,

    - expected characteristics of competing systems, and

    - expected actions of third parties such as equipment suppliers and joint
      venture partners.

    In light of these risks, uncertainties and assumptions, the forward-looking
events discussed in this prospectus might not occur. Additional risks, and
uncertainties and assumptions that we may currently deem immaterial or that are
not presently known to us could also cause the forward-looking events discussed
in this prospectus not to occur. We do not intend to update or revise any
forward-looking statements, whether as a result of new information, future
events or otherwise.

THESE RISKS AND UNCERTAINTIES ARE NOT THE ONLY ONES FACING US.

    Additional risks and uncertainties not presently known to us or that we may
currently deem immaterial may also impair our business operations.

                                       22
<PAGE>
                      WHERE YOU CAN FIND MORE INFORMATION


    Upon effectiveness of the registration statement of which this prospectus is
a part, we will file annual and quarterly and other information with the
Securities and Exchange Commission (the "Commission"). You may read and copy any
reports, statements and other information we file at the Commission's public
reference rooms in Washington, D.C., New York, New York, and Chicago, Illinois.
Please call 1-800-SEC-0330 for further information on the public reference
rooms. Our filings will also be available to the public from commercial document
retrieval services and at the web site maintained by the Commission at
http://www.sec.gov.



    We have filed a registration statement on Form S-4 to register with the
Commission the new notes to be issued in exchange for the old notes. This
prospectus is part of that registration statement. As allowed by the
Commission's rules, this prospectus does not contain all of the information you
can find in the registration statement or the exhibits to the registration
statement.


                                       23
<PAGE>
                               THE EXCHANGE OFFER


    The following contains a summary of the material provisions of the
registration rights agreement. It does not purport to be complete. Reference is
made to the provisions of the registration rights agreement, which has been
filed as an exhibit to the registration statement. Copies are available as set
forth under the heading "Where You Can Find More Information."


TERMS OF THE EXCHANGE OFFER

    GENERAL


    In connection with the issuance of the old notes pursuant to a placement
agreement, dated as of February 12, 1999, between Carrier1 International and the
placement agents, the placement agents and their respective assignees became
entitled to the benefits of the registration rights agreement.



    Under the registration rights agreement, Carrier1 has agreed (1) to use its
best efforts to cause to be filed with the Commission the registration statement
of which this prospectus is a part with respect to a registered offer to
exchange the old notes for the new notes and (2) to use its reasonable best
efforts to consummate the exchange offer within 60 calendar days after the date
on which the registration statement is declared effective. Carrier1 will keep
the exchange offer open for not less than 20 business days after the date notice
of the exchange offer is mailed to holders of the old notes. The exchange offer
being made hereby, if consummated within six months after the initial issuance
of the old notes, will satisfy those requirements under the registration rights
agreement.



    Upon the terms and subject to the conditions set forth in this prospectus
and in the letters of transmittal, all old notes validly tendered and not
withdrawn prior to 5:00 p.m., New York City time, on the expiration date will be
accepted for exchange. New notes of the relevant series will be issued in
exchange for an equal principal amount of outstanding old notes of such series
accepted in the exchange offer. Old notes may be tendered only in integral
multiples of $1,000 or [Euro]1,000, as applicable. This prospectus, together
with the letters of transmittal, is being sent to all registered holders as of
            , 1999. The exchange offer is not conditioned upon any minimum
principal amount of old notes being tendered for exchange. However, the
obligation to accept old notes for exchange pursuant to the exchange offer is
subject to certain customary conditions as set forth herein under
"--Conditions."



    Old notes shall be deemed to have been accepted as validly tendered when, as
and if Carrier1 has given oral or written notice thereof to the exchange agent.
The exchange agent will act as agent for the tendering holders of old notes for
the purposes of receiving the new notes and delivering new notes to such
holders.



    Based on interpretations by the Staff of the Commission as set forth in
no-action letters issued to third parties (including Exxon Capital Holdings
Corporation (available May 13, 1988), Morgan Stanley & Co. Incorporated
(available June 5, 1991), K-III Communications Corporation (available May 14,
1993) and Shearman & Sterling (available July 2, 1993)), Carrier1 believes that
the new notes issued pursuant to the exchange offer may be offered for resale,
resold and otherwise transferred by any holder thereof (other than any such
holder that is a broker-dealer or an "affiliate" of Carrier1 within the meaning
of Rule 405 under the Securities Act) without compliance with the registration
and prospectus delivery provisions of the Securities Act, provided that:



    - such new notes are acquired in the ordinary course of business,



    - at the time of the commencement of the exchange offer such holder has no
      arrangement or understanding with any person to participate in a
      distribution of such new notes, and



    - such holder is not engaged in, and does not intend to engage in, a
      distribution of such new notes.


                                       24
<PAGE>

Carrier1 has not sought, and does not intend to seek, a no-action letter from
the Commission with respect to the effects of the exchange offer, and there can
be no assurance that the Staff would make a similar determination with respect
to the new notes as it has in such no-action letters.



    By tendering old notes in exchange for new notes and executing the
applicable letter of transmittal, each holder will represent to Carrier1 that:



    - any new notes to be received by it will be acquired in the ordinary course
      of business,



    - it has no arrangements or understandings with any person to participate in
      the distribution of the old notes or new notes within the meaning of the
      Securities Act, and


    - it is not an "affiliate," as defined in Rule 405 under the Securities Act,
      of Carrier1 International.


If such holder is a broker-dealer, it will also be required to represent that
the old notes were acquired as a result of market-making activities or other
trading activities and that it will deliver a prospectus in connection with any
resale of new notes. See "Plan of Distribution." Each holder, whether or not it
is a broker-dealer, shall also represent that it is not acting on behalf of any
person that could not truthfully make any of the foregoing representations
contained in this paragraph. If a holder of old notes is unable to make the
foregoing representations, such holder may not rely on the applicable
interpretations of the staff of the Commission and must comply with the
registration and prospectus delivery requirements of the Securities Act in
connection with any secondary resale transaction unless such sale is made
pursuant to an exemption from such requirements.



    Upon consummation of the exchange offer, subject to certain limited
exceptions, holders of old notes who do not exchange their old notes for new
notes in the exchange offer will no longer be entitled to registration rights
and will not be able to offer or sell their old notes, unless such old notes are
subsequently registered under the Securities Act, except pursuant to an
exemption from, or in a transaction not subject to, the Securities Act and
applicable state securities laws. Subject to limited exceptions, Carrier1 will
have no obligation to effect a subsequent registration of the old notes.


    EXPIRATION DATE; EXTENSIONS; AMENDMENTS; TERMINATION


    The expiration date shall be         , 1999, unless Carrier1 International,
in its sole discretion, extends the exchange offer with respect to one or both
series of old notes, in which case the expiration date shall be the latest date
to which the exchange offer is extended with respect to the relevant series.



    To extend the expiration date, Carrier1 International will notify the
exchange agent of any extension by oral or written notice and will notify the
holders of the relevant series of old notes by means of a press release or other
public announcement prior to 9:00 A.M., New York City time, on the next business
day after the previously scheduled expiration date. Such announcement may state
that Carrier1 International is extending the exchange offer for a specified
period of time.



    Carrier1 International reserves the right (1) to delay acceptance of any old
notes, to extend the exchange offer or to terminate the exchange offer and not
permit acceptance of old notes not previously accepted if any of the conditions
set forth herein under "--Conditions" shall have occurred and shall not have
been waived by Carrier1 International prior to the expiration date, by giving
oral or written notice of such delay, extension or termination to the exchange
agent, or (2) to amend the terms of the exchange offer in any manner deemed by
it to be advantageous to the holders of the old notes. Any such delay in
acceptance, extension, termination or amendment will be followed as promptly as
practicable by oral or written notice thereof to the exchange agent. If the
exchange offer is amended in a manner determined by Carrier1 to constitute a
material change, Carrier1 will promptly disclose such amendment in a manner
reasonably calculated to inform the holders of the old notes of such amendment.



    Without limiting the manner in which Carrier1 may choose to make public
announcement of any delay, extension, amendment or termination of the exchange
offer, Carrier1 shall have no obligations to


                                       25
<PAGE>
publish, advertise, or otherwise communicate any such public announcement, other
than by making a timely release to an appropriate news agency.

INTEREST ON THE NEW NOTES


    The new notes will accrue interest at the rate of 13 1/4% per annum from the
last interest payment date on which interest was paid on the old note
surrendered in exchange therefor, or, if no interest has been paid on such old
note, from the issue date of such old note, PROVIDED, that if an old note is
surrendered for exchange on or after a record date for an interest payment date
that will occur on or after the date of such exchange and as to which interest
will be paid, interest on the new note received in exchange therefor will accrue
from the date of such interest payment date. Interest on the new notes is
payable on February 15 and August 15 of each year, commencing August 15, 1999.
No additional interest will be paid on old notes tendered and accepted for
exchange.


PROCEDURES FOR TENDERING


    To tender in the exchange offer, a holder must complete, sign and date the
applicable letter of transmittal, or a facsimile thereof, have the signatures
thereon guaranteed if required by the letter of transmittal, and mail or
otherwise deliver such letter of transmittal or such facsimile, together with
any other required documents, to the exchange agent prior to 5:00 p.m., New York
City time, on the expiration date. In addition, either



    - certificates of such old notes must be received by the exchange agent
      along with the applicable letter of transmittal, or



    - a timely confirmation of a book-entry transfer of such old notes, if such
      procedure is available, into the exchange agent's account at the
      appropriate book-entry transfer facility, that is (1) at The Depository
      Trust Company, in the case of old dollar notes, or (2) at Euroclear and
      Cedel, in the case of old Euro notes, pursuant to the procedure for
      book-entry transfer described below, must be received by the exchange
      agent prior to the expiration date with the applicable letter of
      transmittal, or


    - the holder must comply with the guaranteed delivery procedures described
      below.


THE METHOD OF DELIVERY OF OLD NOTES, LETTER OF TRANSMITTAL AND ALL OTHER
REQUIRED DOCUMENTS IS AT THE ELECTION AND RISK OF THE NOTE HOLDERS. IF SUCH
DELIVERY IS BY MAIL, IT IS RECOMMENDED THAT REGISTERED MAIL, PROPERLY INSURED,
WITH RETURN RECEIPT REQUESTED, BE USED. IN ALL CASES, SUFFICIENT TIME SHOULD BE
ALLOWED TO ASSURE TIMELY DELIVERY. NO OLD NOTES, LETTERS OF TRANSMITTAL OR OTHER
REQUIRED DOCUMENTS SHOULD BE SENT TO CARRIER1. Delivery of all old notes (if
applicable), letters of transmittal and other documents must be made to the
exchange agent at its address set forth below. Holders may also request their
respective brokers, dealers, commercial banks, trust companies or nominees to
effect such tender for such holders.



    The tender by a holder of old notes will constitute an agreement between
such holder and Carrier1 in accordance with the terms and subject to the
conditions set forth herein and in the applicable letter of transmittal. Any
beneficial owner whose old notes are registered in the name of a broker, dealer,
commercial bank, trust company or other nominee and who wishes to tender should
contact such registered holder promptly and instruct such registered holder to
tender on his behalf.



    Signatures on a letter of transmittal or a notice of withdrawal, as the case
may be, must be guaranteed by any member firm of a registered national
securities exchange or of the National Association of Securities Dealers, Inc.,
a commercial bank or trust company having an office or correspondent in the
United States or an "eligible guarantor" institution within the meaning of Rule
17Ad-15 under the Exchange Act (each an "Eligible Institution") unless the old
notes tendered pursuant thereto are tendered (i) by a registered holder of old
notes who has not completed the box entitled "Special Issuance


                                       26
<PAGE>

Instructions" or "Special Delivery Instructions" on the applicable letter of
transmittal or (ii) for the account of an Eligible Institution.



    If a letter of transmittal is signed by trustees, executors, administrators,
guardians, attorneys-in-fact, officers of corporations or others acting in a
fiduciary or representative capacity, such person should so indicate when
signing, and unless waived by Carrier1, evidence satisfactory to Carrier1 of
their authority to so act must be submitted with such letter of transmittal.



    All questions as to the validity, form, eligibility, time of receipt and
withdrawal of the tendered old notes will be determined by Carrier1 in its sole
discretion, which determination will be final and binding. Carrier1 reserves the
absolute right to reject any and all old notes not properly tendered or any old
notes which, if accepted, would, in the opinion of counsel for Carrier1, be
unlawful. Carrier1 also reserves the absolute right to waive any irregularities
or conditions of tender as to particular old notes. Carrier1's interpretation of
the terms and conditions of the exchange offer, including the instructions in
the letters of transmittal, will be final and binding on all parties. Unless
waived, any defects or irregularities in connection with tenders of old notes
must be cured within such time as Carrier1 shall determine. Neither Carrier1,
the exchange agent nor any other person shall be under any duty to give
notification of defects or irregularities with respect to tenders of old notes,
nor shall any of them incur any liability for failure to give such notification.
Tenders of old notes will not be deemed to have been made until such
irregularities have been cured or waived. Any old notes received by the exchange
agent that is not properly tendered and as to which the defects or
irregularities have not been cured or waived will be returned without cost to
such holder by the exchange agent, unless otherwise provided in the letter of
transmittal, as soon as practicable following the expiration date.



    In addition, Carrier1 reserves the right in its sole discretion, subject to
the provisions of the indentures pursuant to which the notes are issued,



    - to purchase or make offers for any old notes that remain outstanding
      subsequent to the expiration date or, as set forth under "--Conditions,"
      to terminate the exchange offer,



    - to redeem old notes as a whole or in part at any time and from time to
      time, as set forth under "Description of the Notes--Optional Redemption,"
      and



    - to the extent permitted under applicable law, to purchase old notes in the
      open market, in privately negotiated transactions or otherwise.



The terms of any such purchases or offers could differ from the terms of the
exchange offer.



ACCEPTANCE OF OLD NOTES FOR EXCHANGE; DELIVERY OF NEW NOTES



    Upon satisfaction or waiver of all of the conditions to the exchange offer,
all old notes properly tendered will be accepted promptly after the expiration
date, and the new notes will be issued promptly after acceptance of the old
notes. See "--Conditions." For purposes of the exchange offer, old notes shall
be deemed to have been accepted as validly tendered for exchange when, as and if
Carrier1 has given oral or written notice thereof to the exchange agent. For
each old note of a series accepted for exchange, the holder of such old note
will receive a new note of the relevant series having a principal amount equal
to that of the surrendered old note.



    In all cases, issuance of new notes for old notes that are accepted for
exchange pursuant to the exchange offer will be made only after timely receipt
by the exchange agent of



    - certificates for such old notes or a timely book-entry confirmation of
      such old notes into the exchange agent's account at the applicable
      book-entry transfer facility,



    - a properly completed and duly executed letter of transmittal, and


    - all other required documents.

                                       27
<PAGE>

If any tendered old notes are not accepted for any reason set forth in the terms
and conditions of the exchange offer, such unaccepted or such nonexchanged old
notes will be returned without expense to the tendering holder thereof (if in
certificated form) or credited to an account maintained with such book-entry
transfer facility as promptly as practicable after the expiration or termination
of the exchange offer.


BOOK-ENTRY TRANSFER


    The exchange agent will make a request to establish an account with respect
to the old notes at the applicable book-entry transfer facility for purposes of
the exchange offer within two business days after the date of this prospectus.
Any financial institution that is a participant in such book-entry transfer
facility's systems may make book-entry delivery of old notes by causing such
book-entry transfer facility to transfer such old notes into the exchange
agent's account at the book-entry transfer facility in accordance with such
book-entry transfer facility's procedures for transfer. However, although
delivery of old notes may be effected through book-entry transfer at the
applicable book-entry transfer facility, the applicable letter of transmittal or
facsimile thereof with any required signature guarantees and any other required
documents must, in any case, be transmitted to and received by the exchange
agent at one of the addresses set forth below under "--Exchange Agent" on or
prior to the expiration date or the guaranteed delivery procedures described
below must be complied with.


EXCHANGING BOOK-ENTRY NOTES


    The exchange agent and the book-entry transfer facility have confirmed that
any financial institution that is a participant in the book-entry transfer
facility may utilize the book-entry transfer facility Automated Tender Offer
Program ("ATOP") procedures to tender old notes.



    Any participant in the applicable book-entry transfer facility may make
book-entry delivery of old notes by causing such book-entry transfer facility to
transfer such old notes into the exchange agent's account in accordance with
such book-entry transfer facility's ATOP procedures for transfer. However, the
exchange for the old notes so tendered will only be made after a book-entry
confirmation of such book-entry transfer of old notes into the exchange agent's
account, and timely receipt by the exchange agent of an agent's message and any
other documents required by the applicable letter of transmittal. The term
"agent's message" means a message, transmitted by the book-entry transfer
facility and received by the Exchange Agent and forming part of a book-entry
confirmation, which states that the book-entry transfer facility has received an
express acknowledgment from a participant tendering old notes that are the
subject of such book-entry confirmation that such participant has received and
agrees to be bound by the terms of the letter of transmittal, and that Carrier1
may enforce such agreement against such participant.


GUARANTEED DELIVERY PROCEDURES

    If the procedures for book-entry transfer cannot be completed on a timely
basis, a tender may be effected if

    - the tender is made through an Eligible Institution,


    - prior to the expiration date, the exchange agent receives by facsimile
      transmission, mail or hand delivery from such Eligible Institution a
      properly completed and duly executed letter of transmittal and notice of
      guaranteed delivery, substantially in the form provided by Carrier1, which



       (1) sets forth the name and address of the holder of old notes and the
           amount of old notes tendered,


       (2) states that the tender is being made thereby, and

                                       28
<PAGE>

       (3) guarantees that within three New York Stock Exchange ("NYSE") trading
           days after the date of execution of the notice of guaranteed
           delivery, the certificates for all physically tendered old notes, in
           proper form for transfer, or a book-entry confirmation, as the case
           may be, and any other documents required by the letter of transmittal
           will be deposited by the Eligible Institution with the exchange
           agent, and



    - the certificates for all physically tendered old notes, in proper form for
      transfer, or a book-entry confirmation, as the case may be, and all other
      documents required by the letter of transmittal are received by the
      exchange agent within three NYSE trading days after the date of execution
      of the notice of guaranteed delivery.


WITHDRAWAL OF TENDERS


    Tenders of old notes of a series may be withdrawn at any time prior to 5:00
p.m., New York City time, on the expiration date with respect to such series.



    For a withdrawal to be effective, a written notice of withdrawal must be
received by the exchange agent prior to 5:00 p.m., New York City time on the
expiration date with respect to such series at one of the addresses set forth
below under "--Exchange Agent." Any such notice of withdrawal must



    - specify the name of the person having tendered the old notes to be
      withdrawn,



    - identify the old notes to be withdrawn, including the principal amount of
      such old notes,



    - in the case of old notes tendered by book-entry transfer, specify the
      number of the account at the book-entry transfer facility from which the
      old notes were tendered and specify the name and number of the account at
      the book-entry transfer facility to be credited with the withdrawn old
      notes and otherwise comply with the procedures of such facility,



    - contain a statement that such holder is withdrawing its election to have
      such old notes exchanged,



    - be signed by the holder in the same manner as the original signature on
      the letter of transmittal by which such old notes were tendered, including
      any required signature guarantees, or be accompanied by documents of
      transfer to have the trustee with respect to the old notes register the
      transfer of such old notes in the name of the person withdrawing the
      tender, and



    - specify the name in which such old notes are registered, if different from
      the person who tendered such old notes.



All questions as to the validity, form, eligibility and time of receipt of such
notice will be determined by Carrier1, whose determination shall be final and
binding on all parties. Any old notes so withdrawn will be deemed not to have
been validly tendered for exchange for purposes of the exchange offer. Any old
notes which have been tendered for exchange but which are not exchanged for any
reason will be returned to the tendering holder therof without cost to such
holder, in the case of physically tendered old notes, or credited to an account
maintained with the applicable book-entry transfer facility for the old notes as
soon as practicable after withdrawal, rejection of tender or termination of the
exchange offer. Properly withdrawn old notes may be retendered by following one
of the procedures described under "--Procedures for Tendering" and "--Book-Entry
Transfer" above at any time on or prior to 5:00 p.m., New York City time, on the
Expiration Date.


CONDITIONS


    Notwithstanding any other provision of the exchange offer, Carrier1 shall
not be required to accept for exchange, or to issue new notes in exchange for,
any old notes and may terminate or amend the exchange offer if at any time prior
to 5:00 p.m., New York City time, on the expiration date, Carrier1 determines in
its reasonable judgment that the exchange offer violates applicable law, any
applicable


                                       29
<PAGE>
interpretation of the staff of the Commission or any order of any governmental
agency or court of competent jurisdiction.


    The foregoing conditions are for the sole benefit of Carrier1 International
and may be asserted by Carrier1 International regardless of the circumstances
giving rise to any such condition or may be waived by Carrier1 International in
whole or in part at any time and from time to time in its reasonable discretion.
The failure by Carrier1 International at any time to exercise any of the
foregoing rights shall not be deemed a waiver of any such right and each such
right shall be deemed an ongoing right which may be asserted at any time and
from time to time.



    In addition, Carrier1 International will not accept for exchange any old
notes tendered, and no new notes will be issued in exchange for any such old
notes, if at such time any stop order shall be threatened or in effect with
respect to the registration statement of which this prospectus constitutes a
part or the qualification of either indenture under the Trust Indenture Act of
1939, as amended. Carrier1 International is required to use every reasonable
effort to obtain the withdrawal of any order suspending the effectiveness of the
registration statement at the earliest possible moment.



EXCHANGE AGENT



    The Chase Manhattan Bank has been appointed as exchange agent for the
exchange offer. Questions and requests for assistance and requests for
additional copies of this prospectus or of the letters of transmittal should be
directed to the exchange agent addressed as follows:



    If tendering a dollar note or requesting information with respect to the
exchange of a dollar note:


<TABLE>
<S>                                            <C>
          BY MAIL, HAND DELIVERY OR                        FOR INFORMATION CALL:
             OVERNIGHT CARRIER:                               (212) 946-3172

          The Chase Manhattan Bank                    FACSIMILE TRANSMISSION NUMBER:
     Capital Markets Fiduciary Services                      (212) 946-8177/78
            450 West 33rd Street                           CONFIRM BY TELEPHONE:
                 15th Floor                                   (212) 946-3172
             New York, NY 10001
          Attention: William Potes
</TABLE>


    If tendering a Euro note that has been deposited with a custodian for, and
registered in the name of, The Depository Trust Company or requesting
information with respect to the exchange of a Euro note deposited with The
Depository Trust Company:


<TABLE>
<S>                                            <C>
          BY MAIL, HAND DELIVERY OR                        FOR INFORMATION CALL:
             OVERNIGHT CARRIER:                               (212) 946-3172

          The Chase Manhattan Bank                     FACSIMILE TRANSMISSION NUMBER
     Capital Markets Fiduciary Services                      (212) 946-8177/78
            450 West 33rd Street                           CONFIRM BY TELEPHONE
                 15th Floor                                   (212) 946-3172
             New York, NY 10001
          Attention: William Potes
</TABLE>

                                       30
<PAGE>

    If tendering a Euro note (except a Euro note deposited with The Depository
Trust Company) or requesting information with respect to the exchange of a Euro
note (except a Euro note deposited with The Depository Trust Company):


<TABLE>
<S>                                            <C>
          BY MAIL, HAND DELIVERY OR                        FOR INFORMATION CALL:
             OVERNIGHT CARRIER:                              (44-171) 777-5414

          The Chase Manhattan Bank                    FACSIMILE TRANSMISSION NUMBER:
     Capital Markets Fiduciary Services                      (44-171) 777-5410
            9 Thomas Moore Street                          CONFIRM BY TELEPHONE:
                London E19YT                                 (44-171) 777-5414
               United Kingdom
           Attention: Chris Greene
</TABLE>

FEES AND EXPENSES


    The expenses of soliciting tenders pursuant to the exchange offer will be
borne by Carrier1. The principal solicitation for tenders pursuant to the
exchange offer is being made by mail; however, additional solicitations may be
made by telegraph, telephone, telecopy or in person by officers and regular
employees of Carrier1.



    Carrier1 will not make any payments to brokers, dealers or other persons
soliciting acceptances of the exchange offer. Carrier1, however, will pay the
exchange agent reasonable and customary fees for its services and will reimburse
the exchange agent for its reasonable out-of-pocket expenses in connection
therewith. Carrier1 may also pay brokerage houses and other custodians, nominees
and fiduciaries the reasonable out-of-pocket expenses incurred by them in
forwarding copies of the prospectus and related documents to the beneficial
owners of the old notes, and in handling or forwarding tenders for exchange.



    The expenses to be incurred by Carrier1 in connection with the exchange
offer will be paid by Carrier1, including fees and expenses of the exchange
agent and trustee and accounting, legal, printing and related fees and expenses.



    Carrier1 will pay all transfer taxes, if any, applicable to the exchange of
old notes pursuant to the exchange offer. If, however, new notes or old notes
for principal amounts not tendered or accepted for exchange are to be registered
or issued in the name of any person other than the registered holder of the old
notes tendered, or if tendered old notes are registered in the name of any
person other than the person signing the letter of transmittal, or if a transfer
tax is imposed for any reason other than the exchange of old notes pursuant to
the exchange offer, then the amount of any such transfer taxes imposed on the
registered holder or any other persons will be payable by the tendering holder.
If satisfactory evidence of payment of such taxes or exemption therefrom is not
submitted with the letter of transmittal, the amount of such transfer taxes will
be billed directly to such tendering holder.


CONSEQUENCES OF FAILURE TO EXCHANGE


    Holders of old notes who do not exchange their old notes for new notes
pursuant to the exchange offer will continue to be subject to the restrictions
on transfer of such old notes as set forth in the legend thereon as a
consequence of the issuance of the old notes pursuant to exemptions from, or in
transactions not subject to, the registration requirements of the Securities Act
and applicable state securities laws. In general, the old notes may not be
offered or sold, unless registered under the Securities Act, except pursuant to
an exemption from, or in a transaction not subject to, the Securities Act and
applicable state securities laws. Carrier1 International does not currently
anticipate that it will register the old notes under the Securities Act. To the
extent that old notes are tendered and accepted in the exchange offer, the
trading market for untendered and tendered but unaccepted old notes could be
adversely affected.


                                       31
<PAGE>
                                USE OF PROCEEDS


    There will be no proceeds from the issuance of new notes pursuant to the
exchange offer.



    The net proceeds from the original offering were approximately $245 million
(based on the February 19, 1999, conversion rate of Euro into U.S. dollars of
[Euro]0.90316 per $1.00), after deducting discounts and commissions and
estimated expenses of the original offering payable by Carrier1 International.
Carrier1 intends to use the net proceeds from the original offering primarily to
finance the construction and start-up costs of the German Network and the
acquisition of transmission capacity, switches, multiplexers, routers and other
equipment. In addition, at the closing of the original offering, Carrier1 used
approximately $49.2 million of the net proceeds to purchase a portfolio of U.S.
government securities and approximately [Euro]26.9 million ($29.8 million) of
the net proceeds to purchase a portfolio of European government securities, and
pledged these portfolios for the benefit of the holders of the respective series
of notes to secure and fund the first five interest payments. The relevant
trustee will hold the pledged securities pursuant to a pledge agreement pending
disbursement. Pending utilization of the net proceeds of the original offering,
Carrier1 has invested such proceeds in short-term investment grade securities
and other financial instruments for the purpose of capital preservation and
liquidity. See "Management's Discussion and Analysis of Financial Condition and
Results of Operations--Liquidity and Capital Resources."


                                       32
<PAGE>
                                DIVIDEND POLICY


    Carrier1 International has never declared or paid any cash dividends on its
shares of common stock and does not expect to do so in the foreseeable future.
Carrier1 International does not expect to generate any net income in the
foreseeable future, but anticipates that future earnings generated from
operations, if any, will be retained to finance the expansion and continued
development of its business. Subject to the declaration of interim dividends by
the Board of Directors, decisions to pay dividends may only be taken by the
shareholders acting at a shareholders' meeting. Any future determination with
respect to the payment of dividends on Carrier1 International's shares will
depend upon, among other things, Carrier1 International's earnings, capital
requirements, the terms of the existing indebtedness, applicable requirements of
Luxembourg corporate law, general economic conditions and such other factors
considered relevant by Carrier1 International's Board of Directors. In addition,
Carrier1 International's ability to pay cash dividends will be restricted under
the terms of the indentures pursuant to which the notes are issued.


                                       33
<PAGE>
                                 CAPITALIZATION

    The following table sets forth the consolidated cash and cash equivalents
and total capitalization of Carrier1 at March 31, 1999.

    Amounts are presented in thousands, except per share data.

<TABLE>
<CAPTION>
                                                                                         MARCH 31, 1999
                                                                                         --------------
<S>                                                                                      <C>
Cash and cash equivalents..............................................................    $  107,960(1)
                                                                                         --------------
                                                                                         --------------
Restricted cash........................................................................         1,446
                                                                                         --------------
                                                                                         --------------
Restricted investments(2)..............................................................       143,034(1)
                                                                                         --------------
                                                                                         --------------
Total long term debt...................................................................       249,608

Shareholders' equity:
  Common Stock, $2 par value, 30,000,000 shares issued and outstanding.................        60,000
  Additional paid-in capital (Warrants)................................................         2,304
  Accumulated deficit..................................................................       (34,265)
  Accumulated other comprehensive income...............................................           836
                                                                                         --------------
      Total shareholders' equity.......................................................        28,875
                                                                                         --------------
        Total capitalization...........................................................    $  278,483
                                                                                         --------------
                                                                                         --------------
</TABLE>

- ------------------------

(1) Assumes the March 31, 1999 conversion rate of Euro into U.S. dollars of
    [Euro]0.92515 per $1.00.

(2) Reflects:


    (a) the portion of the net proceeds from the original offering used to
       purchase government securities to secure and fund the first five
       scheduled interest payments on the notes, see "Description of the
       Notes--Security," and


    (b) approximately $64.8 million used to collateralize a 109.5 million
       Deutsche Mark letter of credit. See the Notes to Unaudited Consolidated
       Financial Statements, Note 5, presented elsewhere in this prospectus.

                                       34
<PAGE>
             UNAUDITED PRO FORMA CONSOLIDATED FINANCIAL INFORMATION


    The following unaudited pro forma consolidated financial information of the
Company has been derived by the application of pro forma adjustments to the
Company's historical consolidated financial statements for the periods from
January 1, 1999 to March 31, 1999 and from Inception to December 31, 1998. The
pro forma consolidated statements of operations give effect to the issuance of
the notes and related transactions as if such transactions had been consummated
on February 20, 1998 (Inception). The adjustments necessary to fairly present
this pro forma consolidated financial information have been made based on
available information and in the opinion of management are reasonable and are
described in the accompanying notes. The pro forma consolidated financial
information should not be considered indicative of actual results that would
have been achieved had the issuance of the notes and related transactions been
consummated on the respective dates indicated and do not purport to indicate
balance sheet data or results of operations as of any future date or for any
future period. You should read the pro forma consolidated financial statements
together with the information set forth in "Use of Proceeds" and the
"Management's Discussion and Analysis of Financial Condition and Results of
Operations," the Consolidated Historical Financial Statements and the notes
thereto, and other financial information included elsewhere in this prospectus.



    The pro forma adjustments were applied to the respective historical
consolidated financial statements to reflect and account for the issuance of the
notes. As a result, such adjustments will have no impact on the historical basis
of either the Company's assets and liabilities. Accordingly, the issuance of the
notes has not impacted the historical basis of the Company's assets and
liabilities.



    The unaudited consolidated pro forma financial statements do not include pro
forma adjustments relating to the effects of foreign currency exchange gains or
losses resulting from the translation of Euro-denominated amounts into U.S.
dollars. Euro-denominated amounts have been translated into U.S. dollars using
an assumed conversion rate of (1) for the period ended December 31, 1998,
[Euro]0.90316 to $1.00, which was the exchange rate on February 19, 1999, the
closing date of the original issuance of the notes and (2) for the period ended
March 31, 1999, [Euro]0.892522 to $1.00, which was the average exchange rate for
such period. Potential dilutive securities have been excluded from the
computation of diluted earnings (loss) per share as their effect is
antidilutive.


    The pro forma ratio of earnings to fixed charges is calculated as the sum of
income before taxes plus interest expense divided by fixed charges. Fixed
charges is the sum of pro forma interest expense and the portion of rental
expense deemed representative of interest. Pro forma earnings were insufficient
to cover fixed charges in the three-month period ended March 31, 1999 by $19.5
million. Pro forma earnings were insufficient to cover fixed charges in the
period from Inception to December 31, 1998 by $49.3 million.

                                       35
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES
            UNAUDITED PRO FORMA CONSOLIDATED STATEMENT OF OPERATIONS
                       THREE MONTHS ENDED MARCH 31, 1999
               (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE DATA)


<TABLE>
<CAPTION>
                                                                           COMPANY      PRO FORMA      COMPANY
                                                                         HISTORICAL    ADJUSTMENTS    PRO FORMA
                                                                        -------------  -----------  -------------
<S>                                                                     <C>            <C>          <C>
Revenues..............................................................  $      12,293               $      12,293
Operating expenses:
  Cost of services....................................................         17,015                      17,015
  Selling, general and administrative.................................          3,318                       3,318
  Depreciation and amortization.......................................          1,336                       1,336
    Total operating expenses..........................................         21,669                      21,669
                                                                        -------------               -------------
Loss from operations..................................................         (9,376)                     (9,376)
Other income (expense):
  Interest expense....................................................         (4,205)     (4,331)(a)        (8,536)
  Interest income.....................................................            979                         979
  Other, net..........................................................         (2,428)                     (2,428)
                                                                        -------------  -----------  -------------
    Total other income (expense)......................................         (5,654)     (4,331)         (9,985)
                                                                        -------------  -----------  -------------
Loss before income tax benefit........................................        (15,030)     (4,331)        (19,361)
Income tax benefit--net of valuation allowance........................             --          --              --
                                                                        -------------  -----------  -------------
Net loss..............................................................  $     (15,030)  $  (4,331)  $     (19,361)
                                                                        -------------  -----------  -------------
                                                                        -------------  -----------  -------------
Earnings (loss) per share:
  Net loss:
    Basic.............................................................  $       (0.53)              $       (0.69)
                                                                        -------------               -------------
                                                                        -------------               -------------
    Diluted...........................................................  $       (0.53)              $       (0.69)
                                                                        -------------               -------------
                                                                        -------------               -------------
Total number of shares used to compute basic earnings
  (loss) per share....................................................     28,145,000                  28,145,000
                                                                        -------------               -------------
                                                                        -------------               -------------
</TABLE>


                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES
       NOTES TO UNAUDITED PRO FORMA CONSOLIDATED STATEMENT OF OPERATIONS


    (a) This adjustment represents the recording of interest expense for the
       period from January 1, 1999 to February 19, 1999 and reflects the
       following:



<TABLE>
<CAPTION>
                                                                                   AMOUNTS IN
                                                                                    THOUSANDS
                                                                                   -----------
<S>                                                                                <C>
Interest expense on the notes....................................................   $   4,227
Amortization of debt issuance costs..............................................          88
Amortization of debt discount....................................................          16
                                                                                   -----------
                                                                                    $   4,331
                                                                                   -----------
                                                                                   -----------
</TABLE>


                                       36
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES
            UNAUDITED PRO FORMA CONSOLIDATED STATEMENT OF OPERATIONS
     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998
               (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE DATA)


<TABLE>
<CAPTION>
                                                                              COMPANY     PRO FORMA    COMPANY
                                                                             HISTORICAL  ADJUSTMENTS  PRO FORMA
                                                                             ----------  -----------  ----------
<S>                                                                          <C>         <C>          <C>
Revenues...................................................................  $    2,792               $    2,792
Operating expenses:
  Cost of services.........................................................      11,669                   11,669
  Selling, general and administrative......................................       8,977                    8,977
  Depreciation and amortization............................................       1,409                    1,409
                                                                             ----------  -----------  ----------
    Total operating expenses...............................................      22,055          --       22,055
                                                                             ----------  -----------  ----------
Loss from operations.......................................................     (19,263)         --      (19,263)
Other income (expense):
  Interest income..........................................................          92                       92
  Interest expense.........................................................         (11)    (29,882)(a)    (29,893)
  Other, net...............................................................         (53)                     (53)
                                                                             ----------  -----------  ----------
    Total other income (expense)...........................................          28     (29,882)     (29,854)
                                                                             ----------  -----------  ----------
Loss before income tax benefit.............................................     (19,235)    (29,882)     (49,117)
Income tax benefit--net of valuation allowance.............................          --          --           --
                                                                             ----------  -----------  ----------
Net loss...................................................................  $  (19,235)  $ (29,882)  $  (49,117)
                                                                             ----------  -----------  ----------
                                                                             ----------  -----------  ----------
Earnings (loss) per share
  Net loss:
    Basic..................................................................  $    (2.61)              $    (6.67)
                                                                             ----------               ----------
                                                                             ----------               ----------
    Diluted................................................................  $    (2.61)              $    (6.67)
                                                                             ----------               ----------
                                                                             ----------               ----------
Total number of shares used to compute basic earnings
  (loss) per share.........................................................   7,367,000                7,367,000
                                                                             ----------               ----------
                                                                             ----------               ----------
</TABLE>


                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES
       NOTES TO UNAUDITED PRO FORMA CONSOLIDATED STATEMENT OF OPERATIONS

    (a) This adjustment represents the recording of interest expense for the
       period from Inception to December 31, 1998 and reflects the following:


<TABLE>
<CAPTION>
                                                                                   AMOUNTS IN
                                                                                    THOUSANDS
                                                                                   -----------
<S>                                                                                <C>
Interest expense on the notes....................................................   $  28,994
Amortization of debt issuance costs..............................................         786
Amortization of debt discount....................................................         102
                                                                                   -----------
                                                                                    $  29,882
                                                                                   -----------
                                                                                   -----------
</TABLE>


                                       37
<PAGE>
                      SELECTED CONSOLIDATED FINANCIAL DATA

    The following table sets forth selected consolidated financial data of
Carrier1 as of and for the period from Inception to December 31, 1998 and as of
and for the three months ended March 31, 1999. The selected consolidated
financial data as of and for the period from Inception to December 31, 1998,
were derived from the consolidated financial statements of the Company which
were audited by Deloitte & Touche Experta AG, independent auditors. The selected
consolidated financial data as of and for the three months ended March 31, 1999,
were derived from the unaudited consolidated financial statements of Carrier1
and include, in the opinion of Carrier1's management, all adjustments,
consisting solely of normal recurring adjustments, necessary to present fairly
the data for such period. The information set forth below is not necessarily
indicative of the results of future operations and should be read in conjunction
with the consolidated financial statements and the related notes thereto
included elsewhere in this prospectus and "Management's Discussion and Analysis
of Financial Condition and Results of Operations."

    Amounts are presented in thousands, except per share data.


<TABLE>
<CAPTION>
                                                                                      THREE MONTHS   INCEPTION TO
                                                                                       ENDED MARCH   DECEMBER 31,
                                                                                        31, 1999         1998
                                                                                      -------------  ------------
<S>                                                                                   <C>            <C>
CONSOLIDATED STATEMENTS OF OPERATIONS DATA:
Revenues............................................................................   $    12,293    $    2,792
Cost of services....................................................................        17,015        11,669
Selling, general and administrative expenses........................................         3,318         8,977
Depreciation and amortization.......................................................         1,336         1,409
                                                                                      -------------  ------------
Loss from operations................................................................        (9,376)      (19,263)
Other income (expense):
Interest income.....................................................................           979            92
Interest expense....................................................................        (4,205)          (11)
Currency exchange loss, net.........................................................        (2,428)          (53)
                                                                                      -------------  ------------
Loss before income tax benefit......................................................       (15,030)      (19,235)
Income tax benefit, net of valuation allowance......................................            --            --
                                                                                      -------------  ------------
Net loss............................................................................   $   (15,030)   $  (19,235)
                                                                                      -------------  ------------
                                                                                      -------------  ------------
Net loss per share (basic)..........................................................   $     (0.53)   $    (2.61)
Net loss per share (diluted)(1).....................................................         (0.53)        (2.61)

OTHER FINANCIAL DATA:
EBITDA (as defined)(2)..............................................................   $    (8,040)   $  (17,854)
Capital expenditures(3).............................................................        11,609        37,168
Ratio of earnings to fixed charges(4)...............................................            --            --
Net cash used in operating activities...............................................       (18,910)      (14,441)
Net cash used in investing activities...............................................      (152,722)      (19,866)
Net cash provided by financing activities...........................................       274,141        37,770
</TABLE>


                                       38
<PAGE>

<TABLE>
<CAPTION>
                                                                                    AS OF
                                                                                  MARCH 31,         AS OF
                                                                                    1999      DECEMBER 31, 1998
                                                                                 -----------  -----------------
                                                                                         (IN THOUSANDS)
<S>                                                                              <C>          <C>
BALANCE SHEET DATA:
Cash and cash equivalents......................................................   $ 107,960(7)    $     4,184
Restricted cash................................................................       1,446            1,518
Restricted investments(5)......................................................     143,034(7)             --
Total assets(6)................................................................     329,777           51,434
Total debt.....................................................................     249,608(7)             --
Shareholders' equity...........................................................      28,875           19,189
</TABLE>

- ------------------------

(1) Potential dilutive securities have been excluded from the computation for
    the period from Inception to December 31, 1998 and for the three months
    ended March 31, 1999 as their effect is antidilutive.


(2) EBITDA stands for earnings before interest, taxes, depreciation,
    amortization and foreign currency exchange gains or losses.



   EBITDA is used by management and certain investors as an indicator of a
    company's historical ability to service debt. Management believes that an
    increase in EBITDA is an indicator of our improved ability to service
    existing debt, to sustain potential future increases in debt and to satisfy
    capital requirements. However, EBITDA is not a measure of financial
    performance under generally accepted accounting principles and should not be
    considered as an alternative to cash flows from operating, investing or
    financing activities as a measure of liquidity or an alternative to net
    income as indications of Carrier1's operating performance or any other
    measure of performance derived under generally accepted accounting
    principles. EBITDA as presented may not be comparable to other similarly
    titled measures of other companies or to Consolidated EBITDA as calculated
    under the indenture pursuant to which the notes are issued.


(3) Consists of purchases of property and equipment and investment in joint
    venture.

(4) The ratio of earnings to fixed charges is calculated as the sum of income
    before taxes plus interest expense divided by fixed charges. Fixed charges
    consist of the total of (1) interest, whether expensed or capitalized, (ii)
    amortization of debt expense and discount or premium relating to any
    indebtedness, whether expensed or capitalized and (iii) that portion of
    rental expense considered to represent interest cost. Earnings were
    insufficient to cover fixed charges by $15.2 million in the three-month
    period ended March 31, 1999, and by $19.5 million in the period from
    Inception to December 31, 1998.

(5) Reflects:


    (a) the portion of net proceeds for the original offering used to purchase
       government securities to secure and fund the first five scheduled
       interest payments on the notes, see "Description of the Notes--Security,"
       and


    (b) approximately $64.8 million used to collateralize a 109.5 million
       Deutsche Mark letter of credit. See the Notes to Unaudited Consolidated
       Financial Statements, Note 5, presented elsewhere in this prospectus.

(6) Includes capitalized financing costs of approximately $8.0 million as of
    March 31, 1999.

(7) Assuming the March 31, 1999 conversion rate of Euro into U.S. dollars of
    [Euro]0.92515 per $1.00.

                                       39
<PAGE>
        MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
                             RESULTS OF OPERATIONS

    THE FOLLOWING DISCUSSION AND ANALYSIS OF CARRIER1'S FINANCIAL CONDITION AND
RESULTS OF OPERATIONS SHOULD BE READ IN CONJUNCTION WITH THE CONSOLIDATED
FINANCIAL STATEMENTS AND THE NOTES THERETO CONTAINED ELSEWHERE IN THIS
PROSPECTUS. CERTAIN INFORMATION CONTAINED IN THE DISCUSSION AND ANALYSIS OR SET
FORTH ELSEWHERE IN THIS PROSPECTUS, INCLUDING INFORMATION WITH RESPECT TO
CARRIER1'S PLANS AND STRATEGY FOR ITS BUSINESS AND RELATED FINANCING, INCLUDES
FORWARD-LOOKING STATEMENTS THAT INVOLVE RISK AND UNCERTAINTIES. SEE "RISK
FACTORS" FOR A DISCUSSION OF IMPORTANT FACTORS THAT COULD CAUSE ACTUAL RESULTS
TO DIFFER MATERIALLY FROM THE RESULTS DESCRIBED IN OR IMPLIED BY THE
FORWARD-LOOKING STATEMENTS CONTAINED HEREIN.

OVERVIEW


    Carrier1 is a rapidly expanding European facilities-based provider of long
distance voice and Internet Protocol data telecommunications services. Carrier1
offers these services on a wholesale basis primarily to competitive fixed-line
operators, other carriers, wireless operators, ISPs, resellers and
multi-national corporations. In March 1998, Carrier1's experienced management
team and Providence Equity Partners formed Carrier1 to capitalize on the
significant voice and data opportunities that are emerging for facilities-based
carriers in Europe's rapidly liberalizing telecommunications markets. By
September 1998, Carrier1 had deployed its initial network and commenced selling
wholesale services. As of December 31, 1998, Carrier1 had executed 48 contracts
with voice customers and 17 contracts with data customers. Also in December
1998, Carrier1 signed a contract with one of the largest telecommunications
companies in Germany, and it expects to carry a substantial portion of this
operator's international traffic. This contract has had a significant impact on
Carrier1's traffic volumes since its recent implementation. As of March 31,
1999, Carrier1 had executed an additional 31 contracts with voice customers and
an additional 18 contracts with data customers.


    Carrier1 is developing an extensive city-to-city European network linking
key population centers. Carrier1 intends to continue rapidly expanding this
network in a cost-effective manner to serve the needs of its existing and
potential customers. Carrier1 believes that its network will allow it to provide
and price its services in Europe on a city-to-city basis without regard to
national borders. This provisioning and pricing structure will put Carrier1 at
the forefront of a shift beginning to occur in the European telecommunications
market away from services and pricing that distinguish between international and
national long distance.


    To date, Carrier1 has experienced net losses and negative cash flow from
operating activities. From Inception to September 1998, Carrier1's principal
activities included developing its business plans, obtaining governmental
authorizations and licenses, acquiring equipment and facilities, designing and
implementing its voice and data networks, hiring management and other key
personnel, developing, acquiring and integrating information and operational
support systems and operational procedures, negotiating interconnection
agreements and negotiating and executing customer service agreements. In
September 1998, Carrier1 commenced the roll-out of its services. Carrier1
expects to continue to generate net losses and negative cash flow as it expands
its operations and does not expect to generate positive cash flow from operating
activities through 2000. Whether or when Carrier1 will generate positive
cashflow from operating activities will depend on a number of financial,
competitive, regulatory, technical and other factors. See "--Liquidity and
Capital Resources."


    Although Carrier1's management is highly experienced in the wholesale
telecommunications business, Carrier1 itself has a limited operating history.
Prospective investors therefore have limited operating and financial information
about Carrier1 upon which to base an evaluation of Carrier1's performance and an
investment in the Carrier1's Securities.

    Carrier1's consolidated financial statements are prepared in accordance with
U.S. generally accepted accounting principles. Carrier1 will be reporting on a
calendar quarterly basis in the future.

                                       40
<PAGE>
FACTORS AFFECTING FUTURE OPERATIONS

    REVENUES


    Carrier1 expects to generate most of its revenues through the sale of
wholesale long distance voice and data services to competitive fixed-line
operators, other carriers, wireless operators, ISPs, resellers and
multi-national corporations. Carrier1 expects to expand the scope of its
wholesale market by adding value-added services for customers such as switchless
resellers. Carrier1 records revenues from the sale of voice and data services at
the time of customer usage. Carrier1's agreements with its voice customers are
typically for an initial term of twelve months and will be renewed automatically
unless cancelled. They employ usage-based pricing and do not provide for minimum
volume commitments by the customer. Carrier1 expects to generate a steady stream
of voice traffic by providing high-quality service and superior customer
support. Carrier1's data services are charged, depending on service type, either
at a flat monthly rate, regardless of usage, based on the line speed and level
of performance made available to the customer, or on a usage basis, with no
minimum volume commitment by the customer. Initially, the majority of Carrier1's
data contracts were usage-based. Since March 31, 1999, Carrier1 has migrated to
offering usage based data pricing only in combination with data contracts that
have a fee-based component that guarantees minimum revenue, in order to
encourage usage of its network services by its data customers. Carrier1's
agreements with its data customers are generally for a minimum term of twelve
months, although Carrier1 may seek minimum terms of two years or more for
agreements providing for higher line speeds. Carrier1 believes that, if the
quality of the service is consistently high, data customers will typically renew
their contracts because it is costly and technically burdensome to switch
carriers.



    Currently, voice and data services are both priced competitively and
Carrier1 emphasizes quality and customer support, rather than offering the
lowest prices in the market. The rates charged to voice and data customers are
subject to change from time to time. Carrier1 will also vary pricing on its
routes as a traffic management tool. Carrier1 initially priced its data services
at an introductory discount to its competitors to build rapidly its customer
base. Carrier1 expects to experience declining revenue per billable minute for
voice traffic and declining revenue per Mb for data traffic, in part as a result
of increasing competition. Carrier1 believes, however, that the impact on its
results of operations from such price decreases will be at least partially
offset by decreases in its cost of providing services and increases in its voice
and data traffic volumes.



    Carrier1's focus on the wholesale international and national long distance
markets will result in its having substantially fewer customers than a carrier
in the mass retail sector. As a result, a shift in the traffic pattern of any
one customer, especially in the near term and on one of Carrier1's high volume
routes, could have a material impact, positive or negative, on Carrier1's
revenues. One customer, whose contract was recently implemented, may account for
up to 30% of Carrier1's revenues in the near term. Furthermore, most wholesale
customers of voice services tend to be price sensitive and, assuming the quality
of service is equivalent, certain customers may switch suppliers for certain
routes on the basis of small price differentials. In contrast, data customers
tend to use fewer suppliers than voice customers, cannot switch suppliers as
easily and, Carrier1 believes, are more sensitive to service quality than to
price.


    COST OF SERVICES

    Cost of services are classified into three general categories: access costs,
transmission costs and termination costs. Carrier1 has minimal access costs as
its wholesale customers are typically responsible for the cost of accessing its
network. Carrier1 intends to target switchless resellers and, for those
services, Carrier1 will have access costs payable to the originating local
provider, usually the incumbent telephone operator. These costs will vary based
on calling volume and the distance between the caller and Carrier1's point of
presence.


    TRANSMISSION COSTS.  Initially, Carrier1's transmission costs for voice and
data traffic will consist primarily of leased capacity charges and switch and
router facilities costs. As a result of Carrier1's objective


                                       41
<PAGE>
to enter the market early, its initial European transmission platform consists
of leased capacity. Leased capacity charges are fixed monthly payments based on
capacity provided and are typically higher than a "dark fiber cost level," which
is Carrier1's target cost level and represents the lowest possible per unit
cost. Dark fiber cost level is the per unit cost of high-capacity fiber that has
been laid and readied for use. Dark fiber cost levels can be achieved not only
through owned facilities, but also may be possible through other rights of use
such as multiple investment units, known as "MIUs."


    As part of Carrier1's strategy to lower its cost base over time, it will
seek dark fiber cost levels for its entire transmission platform, either through
building, acquiring or swapping capacity. Carrier1 will seek to further minimize
its transmission costs by optimizing the routing of its voice traffic and
increasing volumes on its fixed-cost leased and owned lines, thereby spreading
the allocation of fixed costs over a larger number of voice minutes or larger
volume of data traffic, as applicable. To the extent Carrier1 overestimates
anticipated traffic volume, however, per unit costs will increase. As Carrier1
continues to develop its owned network and relies less on leased capacity, per
unit voice transmission costs will decrease substantially, offset partially by
an increase in depreciation and amortization expense. Carrier1 also expects to
experience declining transmission costs per billable minute or per Mb, as
applicable, as a result of decreasing cost of leased transmission capacity,
increasing availability of more competitively priced indefeasible rights of use
and MIUs and increasing traffic volumes.


    VOICE TERMINATION COSTS.  Termination costs represent the costs Carrier1 is
required to pay to other carriers from the point of exit from Carrier1's network
to the final point of destination. Generally, at least one-half of the total
costs associated with a call, from receipt to completion, are
termination-related costs. Voice termination costs per unit are generally
variable based on distance, quality, geographical location of the termination
point and the degree of competition in the country in which the call is being
terminated.


    If a call is terminated in a city in which Carrier1 has a point of presence
and an interconnection agreement with the national incumbent telephone operator,
the call will be transferred to the public switched telephone network for local
termination. This is the least costly mode of terminating a call. To the extent
incumbent telephone operators deny or delay granting Carrier1 interconnection or
grant it interconnection for insufficient capacity or in undesirable locations,
Carrier1 may incur high termination costs, which could have a material adverse
effect on its ability to compete with carriers that do have interconnection
agreements. If a call is to a location in which Carrier1 does not have a point
of presence, or has a point of presence but does not have an interconnection
agreement giving it access to the public switched telephone network, then the
call must be transferred to, and refiled with, another carrier that has access
to the relevant public network for local termination. Carrier1 pays this carrier
a refile fee for terminating its traffic. Most refilers currently operate out of
London or New York, so that the refiled traffic is rerouted to London or New
York and from there is carried to its termination point. Refile agreements
provide for fluctuating rates with rate change notice periods typically of one
or four weeks. To the extent Carrier1 has to rely heavily on refiling to
terminate certain traffic, Carrier1's margins on such voice traffic will be
materially adversely affected. Carrier1 will seek to reduce its refile costs by
utilizing least cost routing. In those countries where Carrier1 has a point of
presence but does not have an interconnection agreement implemented yet, it has
implemented one or more "resale" agreements whereby a local carrier that has an
interconnection agreement with the incumbent telephone operator "resells" or
shares this interconnection right with Carrier1 for a fee. Termination through
resale agreements is significantly less expensive than through refile agreements
because the traffic does not need to be rerouted to another country, as is done
with refiling. Termination through resale agreements is, however, more expensive
than through interconnection agreements. In countries where it has not been
directly authorized to provide services, Carrier1 will negotiate to obtain
direct operating agreements with correspondent telecommunications operators
where such agreements will result in lower termination costs than might be
possible through refile arrangements. Carrier1 believes its refile and resale
agreements are competitively priced. If Carrier1's traffic volumes are higher
than expected, it may have to divert excess traffic onto another carrier's
network, which would also increase its termination costs. Carrier1 believes,
however, that


                                       42
<PAGE>
it has sufficient capacity and could, if necessary, lease more. In addition, its
technologically advanced daily traffic monitoring capabilities allow Carrier1 to
identify changes in volume and termination cost patterns as they begin to
develop, thereby permitting it to respond in a cost-efficient manner.

    Carrier1 believes that its termination costs per unit should decrease as it
extends its network and increases transmission capacity, adds additional
switches and interconnects with more incumbent telephone operators. Carrier1
also believes that continuing liberalization in Europe will lead to decreases in
termination costs as new telecommunications service providers emerge, offering
alternatives to the incumbent telephone operators for local termination, and as
European Union member states implement and enforce regulations requiring
incumbent telephone operators to establish rates which are set on the basis of
forward-looking, long run economic costs that would be incurred by an efficient
provider using advanced technology. There can be no assurance, however,
regarding the extent or timing of such decreases in termination costs.


    DATA TERMINATION COSTS.  Termination costs represent costs Carrier1 is
required to pay to other Internet backbone providers from the point of exit of
Carrier1's network. Data termination is effected through peering and transit
arrangements. Peering arrangements provide for the exchange of data traffic
free-of-charge. Carrier1 has entered into peering arrangements with several ISPs
in the United States and Europe. There can be no assurance that Carrier1 will be
able to negotiate additional peering arrangements or that it will be able to
terminate traffic on their networks at favorable prices. Under transit
arrangements Carrier1 is required to pay a fee to exchange traffic. That fee has
a variable and a fixed component. The variable component is based on monthly
traffic volumes. The fixed component is based on the minimum Mb amount charged
to Carrier1 by its transit partners. The major United States ISPs require almost
all European ISPs and Internet backbone providers, including Carrier1, to pay a
transit fee to exchange traffic. See "Business--Services--Wholesale Data
Service."



    Recently, the Internet services industry has experienced increased merger
and consolidation activity among ISPs and Internet backbone providers. This
activity is likely to increase the concentration of market power of Internet
backbone providers, and may adversely affect Carrier1's ability to obtain
peering arrangements.


    SELLING, GENERAL AND ADMINISTRATIVE EXPENSES

    Carrier1's wholesale strategy allows it to maintain lower selling, general
and administrative expenses than companies providing services to the mass retail
market. Carrier1's selling, general and administrative expenses consist
primarily of personnel costs, information technology costs, office costs,
travel, commissions, billing, professional fees and advertising and promotion
expenses. Carrier1 employs a direct sales force located in the major markets in
which it offers services. To attract and retain a highly qualified sales force,
Carrier1 offers its sales personnel a compensation package emphasizing
performance based commissions and stock options. Carrier1 expects to incur
significant selling and marketing costs in advance of anticipated related
revenue as it continues to expand its operations. Carrier1's selling, general
and administrative expenses are expected to decrease as a percentage of
revenues, however, once it has established its operations in targeted markets
and expanded its customer base.

    DEPRECIATION AND AMORTIZATION

    Depreciation and amortization expense includes charges relating to
depreciation of property and equipment, which will consist principally of
equipment (such as switches, multiplexers and routers), investments in
indefeasible rights of use and in multiple investment units, furniture and
equipment. Depreciation and amortization will also include the amortization of
interest capitalized during the construction of the German Network. Carrier1
depreciates its network over periods ranging from 5 to 15 years and amortizes
its intangible assets over a period of 5 years. Carrier1 depreciates its
investments in indefeasible rights of use and in multiple investment units over
their estimated useful lives of not more

                                       43
<PAGE>
than 15 years. Carrier1 expects depreciation and amortization expense to
increase significantly as Carrier1 expands its owned network, including the
development of the German Network.

RESULTS OF OPERATIONS

    THREE MONTHS ENDED MARCH 31, 1999

    Because Carrier1 commercially introduced its services in September 1998,
Carrier1's management believes that a comparison of results for the three-month
period ended March 31, 1999 to the period from Inception to March 31, 1998 is
not meaningful.

    Revenues for the three-month period ended March 31, 1999 were approximately
$12.3 million, primarily relating to voice services. Cost of services for the
three-month period ended March 31, 1999 was approximately $17.0 million. These
costs consisted of operation of the network, leases for transmission capacity,
and termination expenses including refiling.

    Depreciation and amortization for the three-month period ended March 31,
1999 was approximately $1.3 million and consisted primarily of depreciation
costs for network equipment, indefeasible rights of use, and other furniture and
equipment. Selling, general and administrative expenses were approximately $3.3
million for the three-month period ended March 31, 1999 and consisted primarily
of personnel costs, information technology costs, office costs, professional
fees and expenses.


    Net interest expense for the three-month period ended March 31, 1999 was
approximately $3.2 million. It consisted during this period of approximately
$4.2 million of interest accrued on the notes, less interest income of
approximately $1.0 million. Interest income consists of interest earned from
investing the proceeds of the $60 million dollars invested by funds managed by
Providence and Primus to finance the deployment of Carrier1's network and to
fund start-up operations (the "Equity Investment") and the original offering.
Interest expense increased significantly in this period as compared to the
period from Inception to December 31, 1998 as a result of the issuance of the
notes.


    The strengthening of the U.S. dollar to most European currencies in the
first quarter of 1999 resulted in a currency exchange loss of $2.4 million.

    PERIOD FROM INCEPTION THROUGH DECEMBER 31, 1998

    Carrier1 commercially introduced its services in September 1998. Revenues
for the period from Inception to December 31, 1998 were approximately $2.8
million, primarily relating to voice services. Cost of services for the period
from Inception to December 31, 1998 was approximately $11.7 million. These costs
consisted of operation of the network, leases for transmission capacity, and
termination expenses including refiling.

    Depreciation and amortization for the period from Inception to December 31,
1998 was approximately $1.4 million and consisted primarily of depreciation
costs for network equipment, indefeasible rights of use, and other furniture and
equipment. Selling, general and administrative expenses were approximately $9.0
million for the period from Inception to December 31, 1998 and consisted
primarily of start-up expenses, personnel costs, information technology costs,
office costs, professional fees and promotion expenses.

    Interest income during the period from Inception to December 31, 1998
consisted of interest earned from investing the proceeds of the issuance of
equity. Interest income totaled approximately $81,000 for the period from
Inception to December 31, 1998. No interest expense was incurred for the period
from Inception to December 31, 1998.

                                       44
<PAGE>
LIQUIDITY AND CAPITAL RESOURCES


    From Inception through December 31, 1998, Carrier1 financed its operations
through equity contributions. During the three-month period ended March 31,
1999, Carrier1 financed its operations through additional equity contributions
and with the proceeds of the original offering. The further development of
Carrier1's business and deployment of its network will require significant
capital to fund capital expenditures, working capital, cash flow deficits and
any debt service. Carrier1's principal capital expenditure requirements include
the expansion of its network, including construction of the German Network and
the acquisition of switches, multiplexers, routers and transmission equipment.
Additional capital will be required for office space, switch site buildout and
corporate overhead and personnel.


    Carrier1 estimates it will incur capital expenditures of approximately
$200.0 million from Inception through 1999. By the end of 1999, Carrier1 plans
to complete construction of the German Network and to purchase additional
switches, multiplexers and routers. As of December 31, 1998, Carrier1 had
incurred capital expenditures of approximately $37.2 million since Inception,
including amounts related to the German Network. As of March 31, 1999 Carrier1
had incurred capital expenditures of approximately $11.6 million since December
31, 1998, including amounts related to the German Network. Carrier1's aggregate
funding requirements include requirements to fund capital expenditures, working
capital, debt service and cash flow deficits. Carrier1 estimates, based on its
current business plan, that its aggregate funding requirements for the
deployment and operation of its network will total approximately $280.0 million
through 1999.


    As of December 31, 1998 funds managed by Providence and Primus had invested
a total of approximately $37.8 million to fund start-up operations. As of
February 19, 1999, such funds had completed their aggregate equity investment
totaling $60 million in equity contributions to Carrier1. On February 19, 1999
Carrier1 completed the original offering. Net proceeds from the original
offering were approximately $245 million (based on the February 19, 1999,
conversion rate of [Euro] 0.90316 per $1.00), after deducting discounts and
commissions and estimated expenses of the original offering. Approximately $49.2
million of the net proceeds and [Euro]26.9 million ($29.8 million) of the net
proceeds were used to purchase a portfolio of government securities for the
benefit of the holders of the respective series of notes.



    Carrier1 is also in the process of negotiating a financing facility with a
major equipment supplier. Carrier1 believes, based on its current business plan,
that the net proceeds from the original offering and the Equity Investment,
together with either (1) proceeds of possible sales of dark fiber on the German
Network, (2) proceeds from an accounts receivable facility, if completed, or (3)
proceeds from one or more equipment financing facilities, or a combination of
these sources, will be sufficient to fund the expansion of Carrier1's business
as planned, and to fund operations until Carrier1 achieves positive cash flow
from operations. Carrier1 expects to continue to generate net losses and
negative cash flow as it expands its operations and does not expect to generate
positive cash flow from operating activities through 2000. Whether or when
Carrier1 will generate positive cash flow from operating activities will depend
on a number of financial, competitive, regulatory, technical and other factors.
For example, Carrier1's net losses and negative cash flow from operating
activities are likely to continue beyond that time if:



    - Carrier1 decides to build extensions to its network because it cannot
      otherwise reduce its transmission costs;



    - Carrier1 does not establish a customer base that generates sufficient
      revenue;



    - Carrier1 does not reduce its termination costs by negotiating competitive
      interconnection rates and peering arrangements as it expands its network;



    - prices decline faster than Carrier1 has anticipated;



    - Carrier1 does not attract and retain qualified personnel; or


                                       45
<PAGE>

    - Carrier1 does not obtain necessary governmental approvals and operator
      licenses.



    Carrier1's ability to achieve these objectives is subject to financial,
competitive, regulatory, technical and other factors, many of which are beyond
Carrier1's control. There can be no assurance that Carrier1 will achieve
profitability or positive cash flow.



    The actual amount and timing of Carrier1's future capital requirements may
differ materially from Carrier1's estimates as a result of, among other things,
the demand for Carrier1's services and regulatory, technological and competitive
developments. Sources of additional financing, if available on acceptable terms
or at all, may include commercial bank borrowings, equipment financing or
accounts receivable financing, or the private or public sale of equity or debt
securities.


    On February 18, 1999, Carrier1 entered into an agreement to purchase fiber
optic cable for the German Network during 1999 for $20.3 million plus
value-added tax. The seller will either provide financing for the entire amount
of the purchase with the contract value to be repaid over three years in equal
annual installments beginning on December 31, 2001 together with interest, or
will allow Carrier1 to make payment in full by December 31, 2000 without
interest. The loan, if provided, will bear interest at the U.S. dollar Libor
rate plus 4% per annum. If a loan is not provided, the seller is obligated to
provide certain additional equipment to Carrier1 without charge.

FOREIGN CURRENCY


    Carrier1's reporting currency is the U.S. dollar, and interest and principal
payments on the notes will be in U.S. dollars and Euro. However, the majority of
Carrier1's revenues and operating costs will be derived from sales and
operations outside the United States and will be incurred in a number of
different currencies. Accordingly, fluctuations in currency exchange rates may
have a significant effect on Carrier1's results of operations and balance sheet
data. The Euro has eliminated exchange rate fluctuations among the 11
participating European Union member states. Adoption of the Euro has therefore
reduced the degree of intra-Western European currency fluctuations to which
Carrier1 is subject. Carrier1 will, however, continue to incur revenues and
operating costs in non-Euro denominated currencies, such as pounds sterling.
Although Carrier1 does not currently engage in exchange rate hedging strategies,
it may attempt to limit foreign exchange exposure by purchasing forward foreign
exchange contracts or engaging in other similar hedging strategies. Any
reversion from the Euro currency system to a system of individual country
floating currencies could subject us to increased currency exchange risk. We
have selected our computer and operational systems in an attempt to ensure that
our ability to transact business will not be impaired by complications resulting
from the introduction of the Euro. While we believe that our systems have not
been adversely impacted by the Euro conversion, there can be no assurance that
we will be able to avoid the accounting, billing and logistical difficulties
that might result from the introduction of the Euro. In addition, there can be
no assurance that our third-party suppliers and customers will be able to
successfully implement the necessary protocols.


INFLATION

    Carrier1 does not believe that inflation will have a material effect on its
results of operations.

NEW ACCOUNTING PRONOUNCEMENT

    In June 1998, the Financial Accounting Standards Board issued Statement of
Financial Accounting Standards No. 133, "Accounting for Derivative Instruments
and Hedging Activities." This statement establishes accounting and reporting
standards for derivative instruments embedded in other contracts (collectively
referred to as derivatives) and for hedging activities. It requires that an
entity recognize all derivatives as either assets or liabilities in the
statement of financial position and measure those instruments at fair value. If
certain conditions are met, a derivative may be specifically designated as (a) a
hedge of the exposure to changes in the fair value of a recognized asset or
liability or an unrecognized firm

                                       46
<PAGE>
commitment, (b) a hedge of the exposure to variable cash flows of a forecasted
transaction, or (c) a hedge of the foreign currency exposure of a net investment
in a foreign operation, an unrecognized firm commitment, an available-for-sale
security, or a foreign-currency-denominated forecasted transaction. This
standard is effective for Carrier1's fiscal year ending December 31, 2000.
Management has not yet completed its analysis of this new accounting standard
and, therefore, has not determined whether this standard will have a material
effect on Carrier1's financial statements.

IMPACT OF YEAR 2000


    "Year 2000" generally refers to the various problems that may result from
the improper processing of dates and date-sensitive calculations by computers
and other equipment as a result of computer hardware and software using two
digits, rather than four digits, to define the applicable year. If a computer
program or other piece of equipment fails to properly process dates including
and after the Year 2000, date-sensitive calculations may be inaccurate or a
major system failure may occur. Any such miscalculations or system failures may
cause disruptions in operations including, among other things, a temporary
inability to process transactions, send invoices or engage in other routine
business activities. A failure of Carrier1's computer systems could have a
material adverse effect on its operations, including its ability to make
payments on the notes.


    STATE OF READINESS

    As Carrier1 has developed and implemented its network, operational support
systems, and computer systems, it has conducted an evaluation for Year 2000
compliance. Based on such evaluation, Carrier1 believes that its information
technology ("IT") systems and its non-IT systems, such as its network
transmission equipment and the Nortel and Cisco network operating systems, are
Year 2000 compliant. In addition, Carrier1 has received written assurances from
Cisco, Nortel, and International Computers Limited that the systems they have
provided Carrier1 are Year 2000 compliant. Carrier1, therefore, does not expect
to have to remedy any of its IT or non-IT systems to be Year 2000 compliant.
Carrier1 does not know whether the systems of its vendors, service or capacity
suppliers or customers are or will be Year 2000 compliant. Carrier1 is in the
process of contacting its principal vendors, service or capacity suppliers and
customers and evaluating these parties' efforts to prepare for the Year 2000 and
the degree of its corresponding exposure if such efforts are inadequate.
Carrier1 expects to complete such evaluation by September, 1999.

    RISKS OF YEAR 2000 ISSUES

    Any failure of the computer systems of Carrier1's vendors, service or
capacity suppliers or customers as a result of not being Year 2000 compliant
could materially and adversely affect Carrier1's ability to operate its network
and retain customers. As noted above, Carrier1 is in the process of contacting
its principal vendors, service or capacity suppliers and customers and
evaluating Carrier1's risks associated with their noncompliance.

    CONTINGENCY PLANS AND COSTS TO ADDRESS YEAR 2000 ISSUES

    Carrier1 is still in the process of developing plans, including a
contingency plan to assess the likelihood of and address worst-case scenarios,
to deal with potential Year 2000 problems caused by a failure of its vendors,
service or capacity suppliers or customers to be Year 2000 compliant. Soon after
it completes its on-going evaluation of the likelihood of such a failure,
Carrier1 expects to substantially complete such plans.

    Carrier1 has not incurred any significant costs associated with Year 2000
compliance and does not anticipate incurring significant costs in the future.
Carrier1 may, however, have to bear costs and expenses in connection with the
failure of its vendors, suppliers or customers to be Year 2000 compliant on a
timely

                                       47
<PAGE>
basis. Because no material Year 2000 issues have yet been identified in
connection with external sources, Carrier1 cannot reasonably estimate costs
which may be required for remediation or for implementation of contingency
plans.

RECENT DEVELOPMENTS

    In the second quarter of 1999, Carrier1 began negotiating definitive
documentation for a vendor financing with Nortel and paid Nortel $27.9 million
for equipment delivered prior to April 16, 1999. Also in the second quarter,
Carrier1 entered into several agreements for the exchange of fiber on various
routes. See Note 10 to the Unaudited Consolidated Financial Statements presented
elsewhere in this prospectus.

                                       48
<PAGE>
                                    BUSINESS

OVERVIEW


    Carrier1 is a rapidly expanding European facilities-based provider of long
distance voice and Internet Protocol data telecommunications services. Carrier1
offers these services on a wholesale basis primarily to competitive fixed-line
operators, other carriers, wireless operators, ISPs, resellers and
multi-national corporations. In March 1998, Carrier1's experienced management
team and Providence Equity Partners formed Carrier1 to capitalize on the
significant voice and data opportunities that are emerging for facilities-based
carriers in Europe's rapidly liberalizing telecommunications markets. By
September 1998, Carrier1 had deployed its initial network and commenced selling
wholesale services. As of December 31, 1998, Carrier1 had executed 48 contracts
with voice customers and 17 contracts with data customers. Also in December
1998, Carrier1 signed a contract with one of the largest telecommunications
companies in Germany, and it expects to carry a substantial portion of this
operator's international traffic. This contract has had a significant impact on
Carrier1's traffic volumes since its recent implementation. As of March 31,
1999, we had executed an additional 31 contracts with voice customers and an
additional 18 contracts with data customers.



    Carrier1 is developing an extensive city-to-city European network linking
key population centers. Carrier1 intends to continue rapidly expanding this
network in a cost-effective manner to serve the needs of its existing and
potential customers. Carrier1 believes that its network will allow it to provide
and price its services in Europe on a city-to-city basis without regard to
national borders. This provisioning and pricing structure will put Carrier1 at
the forefront of a shift beginning to occur in the European telecommunications
market away from services and pricing that distinguish between international and
national long distance. As of May 12, 1999, Carrier1 has installed carrier-grade
voice switches and data routers in Amsterdam, Dusseldorf, Frankfurt, London, New
York, Paris, Vienna and Zurich. Carrier1 has a data router in Geneva. By the end
of 1999, Carrier1 expects to have installed voice switches or multiplexers and
data routers and to be providing long distance voice and data services in 21
cities in the following countries: Austria, Belgium, Denmark, Germany, Finland,
France, Ireland, Italy, The Netherlands, Norway, Sweden, Switzerland, the United
Kingdom and the United States.


    To rapidly deploy its network and offer services Carrier1 is initially
leasing its European transmission capacity. However, Carrier1 has entered into a
development agreement to build a 2,300 kilometer fiber network in Germany with
Viatel and Metromedia. This network will connect 14 principal cities and pass a
number of other major cities. It will also provide fiber capacity in regions
Carrier1 believes, based on its management's experience in the European
telecommunications markets, are not covered or are underserved by existing and
announced fiber networks. The important advantages of the German Network are:

    - DIRECT OWNERSHIP. Carrier1 will own its own cable subduct and access
      points. Carrier1's subduct will contain 72 fiber strands.

    - COST. By building with Viatel and Metromedia, Carrier1 shares the fixed
      costs of construction and therefore acquires fiber capacity at a
      significantly lower cost than if it constructed the network itself.

    - FLEXIBILITY. Carrier1 expects that the demand for fiber capacity in the
      regions covered by the German Network will be sufficient to permit it to
      swap excess capacity for fiber capacity on other networks in its target
      markets. Carrier1 would thereby be able to increase the amount of owned
      and controlled capacity at a lower cost.

    Carrier1 expects that construction of the German Network will be completed
by the end of 1999 and that some segments will be operational in the third
quarter of 1999. Carrier1's share of the development costs will be up to
approximately $82 million, including the fiber deployed.

                                       49
<PAGE>
    Stig Johansson, Chief Executive Officer, and Carrier1's management team have
extensive experience in European telecommunications markets and longstanding
relationships with European wholesale customers and suppliers. Mr. Johansson was
formerly the President of Unisource Carrier Services AG, a large European
wholesale carrier of international traffic. Unisource Carrier Services carried
over 400 million minutes of voice traffic in 1997, the large majority of which
was carried for wholesale customers in the same markets that Carrier1 is
addressing. Carrier1's senior management comes from Unisource Carrier Services,
ACC Corp., AT&T-Unisource Communications Services, Telia Norge AS, British
Telecom and AT&T. Mr. Johansson and others in management have also had
significant experience with start-up ventures. See "Management." Carrier1
believes that management's experience and long-standing customer relationships
have been key to its launch of operations approximately six months after its
founding and contracting with a total of 65 customers through December 31, 1998.

    Carrier1 International is a holding company and renders its services
indirectly through subsidiaries primarily located in various Western European
countries. Its registered office is located at L-8009, Strassen, Route d'Arlon
3, Luxembourg. Executive offices of Carrier1 International GmbH, its principal
management services subsidiary, are located at Militarstrasse 36, CH-8004
Zurich, Switzerland. Its phone number is 011-41-1-297-2600.


EUROPEAN VOICE AND DATA MARKET


    OVERVIEW


    In 1997, according to TeleGeography 1999, the European international long
distance market for voice services was the largest in the world, with
approximately 35 billion minutes of use. According to TeleGeography 1999,
Europe's volume of international minutes grew approximately 12% from 1996 to
1997. TeleGeography 1999 projects that global international telecommunications
traffic volume will grow at a compound annual growth rate of 12% to 18% from
1997 to 2001.



    International Data Corporation, as reported by IDCNet, estimates the
European wholesale and retail market for all Internet services was $1.9 billion
in revenue for 1997 and projects that as demand for these services grows,
industry revenues will grow at a compound annual growth rate of approximately
40% to $7.3 billion in 2001, driven primarily by rapid growth in the number of
European Internet users and corresponding demand for bandwidth.


    Carrier1 believes that key factors fueling the ongoing growth in the
European long distance telecommunications market include

    - significant recent regulatory changes in the international and national
      long distance market, resulting in the entry of new telecommunications
      service providers,


    - increasing demand for data services and


    - technological advances, which have substantially increased the
      transmission capacity and reduced the cost of fiber optic capacity.

    LIBERALIZATION AND NEEDS OF NEW ENTRANTS

    The European telecommunications market has historically been dominated by
incumbent telephone operators that have owned and controlled circuits
exclusively within their national boundaries. Cross-border traffic is passed
from one incumbent telephone operator to another at national borders. Tariffs
for this cross-border traffic are determined by a series of bilateral settlement
agreements between incumbent telephone operators known as the accounting rate
mechanism. This system has historically kept the price of cross-border calls in
Europe at levels significantly higher than the underlying cost of transporting
and terminating the calls.

                                       50
<PAGE>

    Liberalization of the European market began in the United Kingdom in 1993.
In March 1996, the European Commission adopted the "Full Competition Directive,"
requiring the complete liberalization of all telecommunications services in most
European Union member states by January 1, 1998. In effect, incumbent telephone
operators are now required to provide interconnection to their network, for both
transmission and termination, to all carriers at certain benchmark prices, and
may not discriminate among carriers. Carrier1 expects that the actual
implementation of the Full Competition Directive in the various European Union
member states will be a gradual process. However, the market liberalization that
has taken place thus far (both within the European Union and in Switzerland and
Norway) has permitted the entry of new competitors seeking to provide a wide
array of international and national telecommunications services. According to
TeleGeography 1999, the number of authorized international carriers in the
United Kingdom was 144 in July 1998, compared to 35 in July 1995, and the number
of authorized international carriers in Germany was 32 in July 1998, compared to
1 in July 1995. Based on its management's understanding of events that occurred
in the United States after liberalization of the U.S. telecommunications
industry, Carrier1 believes that the increased competition triggered by European
market liberalization will lead to further decreases in prices, increases in
international and national long distance traffic, a growing number of new
entrants in the market, a significant decrease in the market share of incumbent
telephone operators over time, and increasing demand for the provision of a
greater number of services at a higher level of quality.


    Another effect of liberalization has been the deployment of European
networks by certain new entrants such as Carrier1, second and third operators,
and infrastructure providers. Cross-border transmission capacity allows new
entrants to offer European telecommunications services priced on a city-to-city
basis without regard to national borders and more closely based on actual costs.
New entrants' prices are lower than the accounting rate mechanism tariffs to
which the incumbent telephone operators adhere. Although an incumbent telephone
operator has low transmission costs within its own country's borders, it cannot
compete with the lower international prices charged by new entrants without
straining the accounting rate mechanism system which has traditionally been an
important source of revenues for the incumbent telephone operators. Furthermore,
as long as an incumbent telephone operator's counterparts adhere to the
accounting rate mechanism, a reduction by one incumbent telephone operator of
its long distance prices may not be matched by a reduction in its termination
costs with other incumbent telephone operators and would therefore have a
negative impact on its margins. The incumbent telephone operators are also
burdened by high overhead costs which are difficult to reduce as quickly as
prices are declining in competitive markets.

    Based on its management's experience in European telecommunications markets,
Carrier1 believes there is an insufficient supply of cost-effective,
cross-border voice services to meet the increasing demand of new entrants, many
of whom do not have network facilities or only have a locally based network.
Carrier1 believes the incumbent telephone operators are not meeting this demand
for a number of reasons:

    - they lack cross-border capabilities and charge high access costs, based on
      the accounting rate mechanism system,

    - their focus has traditionally been on the retail sector,

    - they do not consider it in their short term interest to provide
      cost-effective wholesale services to competitors, and

    - the billing, support and back-office systems of the incumbent telephone
      operators are not designed to address adequately the particular needs of
      new entrants.


As a result, there is an increasing demand by new entrants for alternative
providers of lower cost, high-quality, European and transatlantic voice
services. Carrier1 believes the deficiencies in the supply of cross-border data
services are even more pronounced than those in the supply of voice services.
The


                                       51
<PAGE>

incumbent telephone operators' networks are oriented towards voice traffic and
are not designed to have the flexibility to provide the amounts of capacity that
an ISP is likely to require given the current and projected growth in the volume
of European Internet-related traffic. Therefore, ISPs and other data service
providers operating in the European market are seeking alternative providers of
European and transatlantic data services.



    INCREASING DEMAND FOR DATA SERVICES



    The Internet is a complex, interconnected collection of telecommunications
networks. These networks all use a common suite of protocols, known as TCP/IP,
that facilitate communication with each other. End users connect to the Internet
through dial-up or permanent connections to a network owned by an ISP. ISP
networks are connected to the Internet at network access points or by dedicated
connections to other ISP networks. Each network access point is connected to
other network access points via high capacity telecommunications lines or
backbone facilities. Telecommunications carriers provide the dedicated lines
connecting the ISPs' networks to each other and to the network access points, as
well as the backbone between the network access points. The provision of these
services by these carriers comprises wholesale data services.



    The European Internet market is, according to International Data
Corporation, as reported by IDCNet, several years behind the market in the
United States in terms of overall penetration of data services. Although there
can be no assurance that trends in Europe will follow those in the United
States, Carrier1's management believes that the historical trends in Internet
growth in the United States market with respect to web-users, the number of
Internet host computers through which data services are provided ("hosts") and
backbone capabilities are broadly indicative of what can be expected to occur in
Europe.



    International Data Corporation, as reported by IDCNet, estimates that the
penetration rate of web users in the United States was approximately 12% of the
U.S. population in 1997 and is expected to increase to 38% of the population by
2001. The penetration rate of web users in Western Europe varies across the
region but was estimated on average to be 4% of the population of Western Europe
in 1997. International Data Corporation, as reported by IDCNet, forecasts that
this will more than triple to 15% by 2001. From June 1992 to June 1998,
according to RIPE NCC (the Official Europe Internet Registry), the number of
hosts in Europe increased from approximately 200,000 to 6.8 million,
representing a compound annual growth rate of 80%.



    As the number of Internet web users and hosts increases, demand for backbone
capacity to support growing Internet use is expected to increase
correspondingly. Carrier1 expects European capacity will need to be expanded
significantly over the next few years as European data traffic continues to
grow. As the supply of backbone capacity in Europe increases, the prices of
transmission capacity are expected to decrease significantly. Carrier1 expects
such price decreases will in turn fuel further increases in data service demand.


    TECHNOLOGICAL ADVANCES


    Advances in technology are greatly increasing the transmission carrying
capacity, or bandwidth, of fiber optic cables, while significantly reducing the
incremental cost of this increased capacity. Although building infrastructure
still requires substantial capital expenditures, this increased capacity at
reduced cost made possible by new technology, together with the market
opportunities created by liberalization and growth in data demand, are
encouraging non-incumbent telecommunications companies to build high-quality
European networks. Carrier1 expects that completion of these alternative
cross-border networks will result in increased amounts of high-quality, lower
cost network capacity becoming available through indefeasible rights of use or
long-term leases.


                                       52
<PAGE>
COMPETITIVE STRENGTHS


    Carrier1 believes that a number of factors give it a competitive advantage
in the European long distance voice and data telecommunications markets:


    - EXPERIENCED EUROPEAN MANAGEMENT with many years' experience in the largest
      European telecommunications markets and with strong wholesale customer
      relationships. Carrier1 has a European perspective and, it believes, a
      strong understanding of the European telecommunications markets.

    - A FOCUSED WHOLESALE MARKETING STRATEGY, which allows Carrier1 to service
      new entrants without competing for their retail customers and to operate
      with less overhead than carriers with retail operations.

    - PRICING that disregards the existence of national borders and gives
      Carrier1 more flexibility than the incumbent telephone operators to
      compete on the basis of price.

    - ADVANCED INFORMATION AND CONTROL SYSTEMS that allow Carrier1 to optimize
      pricing and network use on a real-time basis.


    - PROVISION OF HIGH-QUALITY VOICE AND DATA SERVICES expected by European
      customers. Carrier1 believes that its guarantees of high performance
      levels distinguish it from its competitors.


    - DELIVERY OF SUPERIOR CUSTOMER SUPPORT exceeding that provided in Europe
      today. Carrier1 offers rapid implementation and response times and locally
      based customer-oriented sales and support personnel.

    - LACK OF AFFILIATION WITH AN INCUMBENT TELEPHONE OPERATOR, which allows
      Carrier1 complete flexibility to market its services broadly to its target
      customers, including carriers who compete with incumbent telephone
      operators.

BUSINESS STRATEGY


    Carrier1's objective is to become a leading European wholesale provider of
high quality long distance voice and data services, by capitalizing on the
rapidly increasing demand for city-to-city European voice and data services. The
key elements of Carrier1's strategy are:



    - TARGET WHOLESALE MARKETS. Carrier1 offers wholesale services primarily to
      competitive fixed-line operators, other carriers, wireless operators,
      ISPs, resellers and multi-national corporations. In particular, Carrier1
      focuses its marketing efforts on competitive retail operators who lack
      international infrastructure. Based on its management's experience in
      European telecommunications markets, Carrier1 believes these new entrants
      prefer an independent supplier of wholesale services to an incumbent
      telephone operator or other supplier with which they compete directly.
      Concentrating on the wholesale market allows Carrier1 to operate with less
      overhead than other carriers with mass retail operations and to implement
      operational support systems tailored to meet the needs of wholesale
      customers. By focusing on the wholesale sector and making its main
      business the selling of voice and data services, Carrier1 will take
      advantage of its management's strong market-oriented skills, first-hand
      understanding of the European telecommunications markets and long-standing
      wholesale customer relationships.


    - FOCUS ON CUSTOMER NEEDS. Carrier1 believes that both high quality of
      service and strong customer support are essential to capitalize
      successfully on market opportunities.


       QUALITY OF SERVICE: Carrier1 believes that quality of service is critical
       to obtaining and retaining customers. Carrier1's technologically advanced
       voice and data network and network management and information systems
       allow it to offer its services at guaranteed minimum levels of order
       implementation, response and repair time, and at a 99.9% network
       availability level. Based on its


                                       53
<PAGE>

       management's experience in telecommunications markets, Carrier1 believes
       no other carrier in Europe offers a better minimum service level for
       voice or data services. Because it owns its switches, multiplexers and
       routers, which are key components of its network, Carrier1 can control
       the quality and breadth of its service offerings.


       SUPERIOR CUSTOMER SUPPORT: Based on its management's experience in
       telecommunications markets, Carrier1 believes that customer support
       levels in the wholesale telecommunications market in Europe are generally
       lower than those in the United States. Carrier1 has designed its systems
       to provide a level of customer support significantly higher than that
       generally offered in the wholesale market in Europe. Key features of
       these systems include: (1) decentralized sales, installation and basic
       support, facilitating quick response to customer needs, (2) a help desk
       operating 24 hours a day, 365 days a year, (3) on-line order management
       and provisioning, traffic reports, fault reports and repair information
       and (4) on-line customized billing.

    - RAPID, COST-EFFECTIVE CITY-TO-CITY NETWORK DEPLOYMENT. Carrier1 has
      developed a cross-border network linking principal cities of Western
      Europe and will continue to broaden the range of countries covered by the
      network and deepen the extent of the network within particular countries.
      To capitalize on its early entry into the market and to rapidly expand its
      presence, Carrier1 is pursuing an aggressive timetable for extending the
      scope of its network, in part by leasing capacity and outsourcing certain
      functions. Carrier1's longer term goal is to own or control key elements
      of its network and to assume control of key outsourced functions. To
      establish points of presence rapidly and cost-effectively in selected new
      markets, Carrier1 is initially using multiplexers. Multiplexers are less
      costly and easier to install than switches, enhance Carrier1's flexibility
      and service quality and help to reduce its termination costs. As traffic
      increases, Carrier1 may replace multiplexers with switches and redeploy
      these multiplexers in new markets. Carrier1's city-to-city network will
      (1) allow it to price its services within Western Europe without regard to
      national borders, (2) bring it closer to a greater number of customers and
      (3) reduce its termination costs.


    - REDUCE TRANSMISSION COSTS. A key part of Carrier1's strategy is to reduce
      the costs of its transmission platform. Carrier1 intends to reduce its
      transmission costs by continually evaluating whether to build, buy or
      lease capacity or swap excess capacity. While Carrier1 currently holds two
      transatlantic indefeasible rights of use, Carrier1 is currently leasing
      the rest of its transmission capacity because doing so enabled Carrier1 to
      commence offering services in its target markets rapidly. In addition,
      construction of new capacity has been announced in many of Carrier1's
      target markets and, based on its management's knowledge of the European
      telecommunications markets, Carrier1 believes the cost of acquiring
      capacity in those regions is decreasing and will continue to decrease. The
      German Network illustrates an opportunity where Carrier1's management
      believes it is more cost effective to build capacity. As demand for voice
      and data services in Europe increases and new networks are constructed,
      Carrier1 believes there will be significant opportunities to add new and
      replace existing transmission capacity at lower unit cost. Carrier1 also
      intends, as soon as proven technology is commercially available, to
      migrate to a single, data-based transmission platform for both voice and
      data services. This platform would permit Carrier1 to increase the cost
      effectiveness of its operations through more efficient use of its
      transmission capacity.


    - INTRODUCE NEW VALUE-ADDED SERVICES. Carrier1 intends to expand its
      addressable market to include additional wholesale customers, such as
      switchless resellers, by offering the value-added services they require.
      These services include capabilities for switched access, toll-free
      services and prepaid phone cards. Carrier1 plans to offer these wholesale
      capabilities in selected countries as early as mid-1999.

    - REDUCE COSTS THROUGH INTERCONNECTION AGREEMENTS AND PEERING. By
      establishing interconnection arrangements with incumbent telephone
      operators in liberalized markets and direct operating agreements with
      incumbent telephone operators in emerging markets, Carrier1 can keep its
      costs of

                                       54
<PAGE>

      terminating calls lower and exercise greater control over quality and
      transmission capacity than it can using refile or resale agreements.
      Similarly, entering into additional peering agreements will minimize the
      cost of terminating Carrier1's data traffic.


SERVICES


    Carrier1 is focusing on providing long distance voice and data services on a
wholesale basis at the high level of quality expected by European customers. It
provides these services primarily to competitive fixed-line operators, other
carriers, wireless network operators, ISPs, resellers and multi-national
corporations. In September 1998, Carrier1 launched its European and
transatlantic international long distance voice and data services. It expects to
begin providing national long distance services in the first half of 1999 inside
the United Kingdom and Germany. Carrier1 intends, by the end of 1999, to be a
broadly based European provider of voice and data services, able to provide and
price its services on a city-to-city basis without regard to national borders.
Carrier1 intends to provide in the future other wholesale telecommunications
services, such as managed bandwidth and voice-over-IP (voice traffic transmitted
over a data-based network) services.


    WHOLESALE VOICE SERVICE

    Carrier1's wholesale voice service involves city-to-city transport from
Carrier1's network points of presence located in strategic European cities and
New York for termination anywhere in the world. Carrier1 terminates calls either
through interconnection or direct operating agreements with the relevant
national incumbent telephone operator or through refile or resale agreements
with other carriers that have interconnection agreements in place with that
incumbent. When Carrier1 does use refile or resale agreements to terminate
traffic it seeks to do so with carriers who provide voice service comparable in
quality to Carrier1's. Carrier1's customers generally will arrange for
transmission of their traffic to one of Carrier1's points of presence at their
own cost, although Carrier1 may provide service from the customer's site if
traffic volume is sufficient. Carrier1's voice service contracts guarantee 99.9%
availability on the network and certain minimum connection response and repair
times.


    WHOLESALE DATA SERVICE



    Carrier1 seeks to be a major European Internet backbone provider. It offers
two types of wholesale data transport service, "Global Transit Services" and
"Internet Exchange Connect Services."



    GLOBAL TRANSIT SERVICE.  Carrier1's Global Transit Service provides
customers with high-speed, high-quality connectivity to Internet domain
addresses world-wide. This backbone service interconnects Carrier1's customers
with selected Internet exchanges and other international Internet backbone
providers. Customers connected to the Global Transit Service backbone have
any-to-any connectivity geared to providing the best Internet reach and
connectivity. Although Carrier1 anticipates that most of its data customers will
bring their traffic to Carrier1's routers, Carrier1 will consider, on a case by
case basis, alternative arrangements.


    Carrier1 offers two levels of Global Transit Service: "Premium" and "Basic."
Both packages guarantee certain minimum connection, response and repair times.
The Premium Transit package guarantees certain additional performance parameters
and will be given priority within the network. A Premium Transit user's
guaranteed service levels include round trip packet delay of less than 100
milliseconds, packet loss of less than 0.2%, 99.9% availability on Carrier1's
network and the highest level of traffic prioritization. At peak traffic hours,
the Premium user's traffic has priority over the Basic user's traffic. Carrier1
has designed its network, however, to minimize the likelihood of congestion
requiring such prioritization of traffic. Both the Basic and Premium packages
offer customers newsfeed services and a backup to the customer's primary
Internet address.

                                       55
<PAGE>

    Carrier1's Global Transit Service is interconnected in Europe to Ebone, a
subsidiary of Hermes Europe RailTel B.V. ("Hermes"), that has what Carrier1's
management believes is a large European customer base. Carrier1 initially will
pay a transit fee for access to the Ebone Internet backbone. Carrier1 will also
actively seek to enter into peering arrangements with smaller European backbone
providers. As its volume of data traffic increases, Carrier1 expects it will be
in a position to negotiate peering with Ebone and other major European backbone
providers. In the United States, where almost all European backbone providers
must pay to access the backbones of the major United States Internet backbone
providers, Carrier1 has transit agreements with UUNet Technologies, Inc., an MCI
WorldCom subsidiary ("UUNet"), and GTE Internetworking, a unit of GTE
Corporation. In the United States, Carrier1 has peering arrangements with Epoch
Networks and PSINet. In Europe, Carrier1 has peering arrangements with a number
of ISPs. Based on its management's knowledge of the European Internet market,
Carrier1 believes its Global Transit Service offers connectivity to a greater
number of United States Internet backbone providers than other European data
services. Carrier1 will also interconnect Global Transit Service customers to
each other, which, as the customer base of its backbone grows, will increase the
attractiveness to customers of Carrier1's Internet backbone.



    INTERNET EXCHANGE CONNECT SERVICE.  Carrier1's Internet Exchange Connect
Service (the "IX Connect") is a point-to-point option for customers who want to
transit solely to a specific Internet exchange or to a specific partner. It
offers one-to-one connectivity to a select number of destinations through main
Internet exchanges in Europe and the United States. Carrier1 currently offers IX
Connect connectivity to LINX in London, AMS-IX in Amsterdam, DE-CIX in
Frankfurt, CIPX in Geneva, PARIX in Paris and several Internet backbone
providers in New York. As its network expands, Carrier1 expects to offer
connectivity to additional network access points. Based on its management's
knowledge of the European Internet market, Carrier1 believes it is the only
European data service provider currently offering this type of service. The
service is targeted to large ISPs who prefer to organize their own presence and
peerings in the key Internet exchanges for technical or commercial reasons. The
principal guaranteed parameters of IX Connect are dedicated reserved capacity,
access speed ranging from 2 Mb to 155 Mb and the announcement of the customer's
Internet domain at the remote location. Carrier1 will also guarantee certain
minimum connection, response and repair times.



    A large number of customers are significant to Carrier1's Internet backbone
because (1) it increases the cost-efficient use of the network by lowering per
unit costs, (2) it facilitates obtaining lower per unit transit fees or peering
with other ISPs and (3) it augments the value of the backbone which, in turn,
draws more customers.



    Both types of data services include a centralized help desk and network
management on a 24-hours-a-day, 365-days-a-year basis, Web site reporting and
service information, on-line statistics per customer on a secure basis and Web
site diagnostic tools.


    OTHER SERVICES

    Carrier1 has started to introduce managed bandwidth and data services.
Carrier1 intends to introduce other new value-added services, as described above
under "--Business Strategy."


    Carrier1 also intends to offer Voice-over-IP ("VoIP"), or voice traffic
transmitted over a data-based network. Carrier1 plans, after a trial phase
expected to be completed by mid-1999, to offer VoIP to data customers that, for
example, wish to offer personal computer-to-phone connectivity to their end
users. Carrier1 also plans to offer other value-added data services, such as
server co-location facilities for its current and future customers.


    As Carrier1 extends its network and adds transmission capacity, it expects
that it will be able to sell excess bandwidth.

                                       56
<PAGE>
NETWORK

    Carrier1 believes it is critical to own or control key elements of its
network in order to become a high-quality, low-cost provider. Carrier1 is
following a flexible, phased approach to deploying its network that will permit
it to optimize the use of its network and take advantage of low-cost
opportunities for expanding the network. Carrier1 has commenced operations
primarily on a leased fiber optic transmission platform to enable its early
entry into the market. Over time, Carrier1 will expand its network in a phased
approach, adding capacity to meet expected increases in demand. To reduce its
cost base, however, Carrier1 will seek to obtain additional transmission
capacity at dark fiber cost levels, either through building new capacity,
acquiring capacity through purchases or swaps of excess capacity or leasing
capacity. In all cases, Carrier1 intends to own its switches and routers.


    The table below sets forth as of May 12, 1999, the location of each switch,
multiplexer and router owned by Carrier1 and in service, and the location and
currently expected in-service dates of switches, multiplexers and routers
planned to be installed through the end of 1999. However, the timing, location
and number of switches, multiplexers and routers may change depending on changes
in customer demand or regulatory conditions in any particular jurisdiction, or
the availability of a single data-based transmission platform.


<TABLE>
<CAPTION>
                 INSTALLED NETWORK COMPONENTS (AS OF MAY 12, 1999)
- ------------------------------------------------------------------------------------
<S>            <C>          <C>             <C>          <C>             <C>
                         VOICE                                      DATA
- -------------------------------------------------------  ---------------------------

<CAPTION>
         SWITCHES                  MULTIPLEXERS                    ROUTERS
- --------------------------  ---------------------------  ---------------------------
<S>            <C>          <C>             <C>          <C>             <C>
Amsterdam                   Geneva                       Amsterdam
Dusseldorf                                               Dusseldorf
Frankfurt                                                Frankfurt
London                                                   Geneva
New York                                                 London
Paris                                                    New York
Vienna                                                   Paris
Zurich                                                   Vienna
                                                         Zurich
<CAPTION>

        PLANNED NETWORK INSTALLATIONS BY YEAR END 1999 (AS OF MAY 12, 1999)
- ------------------------------------------------------------------------------------
                         VOICE                                      DATA
- -------------------------------------------------------  ---------------------------
         SWITCHES                  MULTIPLEXERS                    ROUTERS
- --------------------------  ---------------------------  ---------------------------
                EXPECTED                     EXPECTED                     EXPECTED
               IN-SERVICE                   IN-SERVICE                   IN-SERVICE
LOCATION          DATE         LOCATION        DATE         LOCATION        DATE
- -------------  -----------  --------------  -----------  --------------  -----------
<S>            <C>          <C>             <C>          <C>             <C>
Berlin             2Q '99   Cologne             3Q '99   Berlin              2Q '99
Hamburg            2Q '99   Copenhagen          3Q '99   Brussels            2Q '99
Brussels           3Q '99   Dublin              3Q '99   Hamburg             2Q '99
Manchester         3Q '99   Stuttgart           3Q '99   Milan               3Q '99
Milan              3Q '99   Helsinki            4Q '99   Cologne             3Q '99
Stockholm          3Q '99   Leipzig             4Q '99   Copenhagen          3Q '99
                            Munich              4Q '99   Dublin              3Q '99
                            Oslo                4Q '99   Manchester          3Q '99
                                                         Stockholm           3Q '99
                                                         Stuttgart           3Q '99
                                                         Helsinki            4Q '99
                                                         Leipzig             4Q '99
                                                         Munich              4Q '99
                                                         Oslo                4Q '99
</TABLE>


                                       57
<PAGE>
    EXISTING NETWORK


    Carrier1's management believes that entering the liberalizing European
international and national long distance markets early and establishing its
position quickly with a technologically advanced voice and data network will
give Carrier1 a competitive advantage in such markets. To begin operations in
September 1998, approximately six months after being founded, and to keep its
overhead costs as low as possible, Carrier1 outsourced to Nortel and Cisco, on a
turnkey basis, the design, installation, technical operation and maintenance of
its initial network. Carrier1 has assumed operation of the functions that were
outsourced to Cisco. Carrier1 expects to assume control from Nortel of technical
operations of the network by mid-1999. By applying its operational knowledge and
expertise to the deployment process, management believes it has succeeded in
putting in place one of the most advanced voice and data networks in Europe.


    TRANSMISSION CAPACITY.  Carrier1's traffic is transmitted over: (1) an STM 1
(155Mb) circuit on the Gemini fiber optic cable, acquired from Telemonde under
an indefeasible right of use, linking London and New York, (2) an STM-1 (155Mb
equivalent) circuit leased from Hermes (the "Hermes Ring") connecting Amsterdam,
Frankfurt, Geneva, London and Paris, (3) a 155Mb leased circuit linking
Frankfurt to Vienna, (4) a 155Mb leased circuit linking Frankfurt to Dusseldorf,
(5) a 155Mb leased circuit linking Frankfurt and Zurich, and (6) an STM-1
circuit on the AC-1 fiber optic cable, acquired under an indefeasible right of
use, linking Frankfurt and New York.

    NETWORK MANAGEMENT CAPABILITIES.  Carrier1 has installed Synchronous Digital
Hierarchy ("SDH") equipment at each network point of presence that will provide
it with information relating to the status and performance of all elements of
its network, including the transmission capacity provided to it by various third
parties. This SDH layer will also provide Carrier1 with flexibility to connect
new providers of transmission capacity and to configure this capacity in a
flexible manner.

    VOICE TRAFFIC.  Carrier1 had, as of March 31, 1999, five Nortel
international gateway GSP switches in Frankfurt, London, New York, Vienna and
Zurich. Carrier1 selected these cities because the United States, Germany and
the United Kingdom represented either the source or termination points for 20 of
the top 25 traffic routes in the world in 1996. Carrier1's switches and
switching system are the most advanced Nortel currently supplies and its main
transmission lines are redundant. In addition, as of March 31, 1999, Carrier1
had installed multiplexers in Amsterdam, Geneva and Paris. Carrier1 has, as of
May 12, 1999, added switches in Amsterdam, Dusseldorf and Paris.


    DATA TRAFFIC.  Carrier1 had, as of May 12, 1999, high-capacity Cisco routers
in Amsterdam, Dusseldorf, Frankfurt, Geneva, London, New York, Paris, Vienna and
Zurich. Carrier1 selected these cities because they represent important sites of
European data traffic origination or termination.



    Carrier1 has configured its routers and leased circuits into a ring and
believes, based on its management's knowledge of data services markets, it is
one of the first carriers in Europe to provide data services on a ring
structure. This technologically advanced ring architecture, enhanced by SDH
equipment, provides inherent redundancy. Upon any single failure on the ring,
traffic will automatically be re-routed to another part of the ring, avoiding
transmission failure. Based on its management's knowledge of the European
Internet market, Carrier1 believes it has one of the most advanced data networks
in Europe.


    PLANNED NETWORK DEPLOYMENT

    Carrier1 is continuing to pursue an aggressive timetable for extending the
scope of its network, thereby rapidly expanding its presence in its target
markets. Carrier1 is installing a cross-border network linking the principal
cities of several Western European countries and will continue to broaden the
range of countries covered by the network and deepen the extent of the network
within particular countries. With a city-to-city cross-border network in place,
Carrier1 will be able to provide and price its services without regard to
national boundaries.

                                       58
<PAGE>
    VOICE TRAFFIC.  Carrier1's deployment schedule through the end of 1999
contemplates the acquisition and installation of multiplexers or Nortel GSP
switches in Berlin, Brussels, Cologne, Copenhagen, Dublin, Hamburg, Helsinki,
Leipzig, Manchester, Milan, Munich, Oslo, Stockholm and Stuttgart. Since March
31, 1999, Carrier1 has replaced multiplexers in Amsterdam, Dusseldorf and Paris
with Nortel GSP switches. These sites, together with Carrier1's existing sites,
serve large population centers and points of traffic concentration in France,
Germany and the United Kingdom. By expanding the range of its network within
these countries Carrier1 will gain closer access to a larger number of customers
and will reduce its interconnection and other termination-related costs. In
considering similar network penetration levels in other European countries,
Carrier1 will weigh the benefits of increased access to customers and lower
termination costs against the increased transmission costs incurred.


    The timing of installation and location of each of the switches above may
change in response to changes in customer demand, the availability of a single
data-based transmission platform, or changes in regulatory conditions in any
particular jurisdiction.



    DATA TRAFFIC.  Carrier1's deployment schedule through the end of 1999
contemplates the installation of routers in Berlin, Brussels, Cologne,
Copenhagen, Dublin, Hamburg, Helsinki, Leipzig, Manchester, Milan, Munich, Oslo,
Stockholm and Stuttgart.



    The timing of installation and location of each of the routers listed above
may change in response to changes in customer demand or the availability of a
single data-based transmission platform.


    THE GERMAN NETWORK.  Carrier1 has entered into a Development Agreement to
build the German Network with affiliates of Viatel and Metromedia, targeting
routes it believes are currently underserved by existing and announced fiber
networks. The German Network will be an advanced, high-capacity, bi-directional
self-healing 2,300 kilometer fiber optic ring utilizing advanced SDH and dense
wave division multiplexing technologies. The German Network will initially
connect Berlin, Bremen, Cologne, Dortmund, Dresden, Dusseldorf, Essen,
Frankfurt, Hamburg, Leipzig, Mannheim, Munich, Nuremberg, and Stuttgart. The
German Network will also pass a number of other major cities. When the German
Network is completed, Carrier1 will own its own cable subduct and access points.
Carrier1's cable subduct will contain 72 strands of fiber. Carrier1 expects that
construction of the German Network will be completed by the end of 1999 and that
some segments will be operational in the third quarter of 1999. Carrier1's share
of the development costs will be up to approximately $82 million, including the
fiber deployed.

    Carrier1 has decided to commence building an extension of its network in
Germany because

    - Germany is the largest telecommunications market in Europe and a major
      center for traffic within Europe,

    - there is limited availability of cost-effective transmission capacity in
      Germany,

    - leased transmission costs are currently very high in Germany and Carrier1
      desires to lower its cost base in such a large market,

    - Germany's population is widely and relatively evenly dispersed among many
      cities, requiring the installation of a number of switches and routers
      throughout the country to effectively access the full range of potential
      customers,

    - installing multiple points of presence in Germany will reduce Carrier1's
      termination costs, and

    - Germany's central location within Europe provides a good base from which
      to connect the German Network to other parts of Europe.

The German Network will also provide fiber capacity in regions Carrier1 believes
are not covered or are underserved by existing and announced fiber networks.
Carrier1 also believes that excess capacity on the German Network will be useful
as a valuable "currency" to swap for capacity on other networks.

                                       59
<PAGE>

    Carrier1 and its joint venture partners have not yet received all of the
rights-of-way, wayleaves or government approvals for the construction in the
German Network, but are currently in the process of obtaining them.


    Pursuant to the Development Agreement, Carrier1 and Metromedia each have a
24.995% interest and Viatel has a 50.01% interest in the development company.
Viatel, as a result of its majority interest, will control all but certain major
decisions relating to the development of the German Network which will require
unanimous consent. Costs of construction will be borne pro rata by Viatel,
Carrier1 and Metromedia, and the development company will be indemnified for
certain liabilities, costs and expenses by each of the parties. In addition,
Viatel will receive a developer's fee of 3% of certain construction costs, 25%
of which will be paid by Carrier1.

    Viatel and Metromedia are each required to provide the development company
with a letter of credit. The development company may draw on the letter of
credit of a party that does not meet its funding obligations. Carrier1 has
provided a letter of credit in the amount of approximately DM 110 million (or
approximately $64.8 million).

    OTHER PLANNED TRANSMISSION CAPACITY.  During the year 2000 Carrier1 also
expects TAT-14, a transatlantic cable connecting Amsterdam, London and New York
in which it has arranged to purchase a multiple investment unit, to become
operational. By that time, Carrier1 also expects to have replaced some leased
capacity with owned capacity and to have leased or purchased additional capacity
for geographic and volume expansions. By the third quarter of 1999, Carrier1
expects to have in operation additional transmission capacity which it has
acquired on rings connecting (1) Frankfurt, Amsterdam, London and Paris (dark
fiber), (2) Hamburg, Copenhagen, and Malmo (wavelength) and (3) Frankfurt,
Amsterdam, London, Paris and Brussels (wavelength).

    FURTHER NETWORK EXTENSIONS AND DEVELOPMENTS

    Carrier1 will consider extending its network within Europe beyond its
current deployment plans through 1999. Due to the rapidly evolving dynamics of
the European telecommunications market, Carrier1 will continually reassess the
most cost-effective means of network expansion. Future increases in the supply
of fiber optic cable may make variable or fixed-rate lease arrangements, the
purchase of transmission rights or the swapping of transmission capacity more
favorable options, in economic terms, than building new capacity.


    Carrier1 has worked closely with Nortel and Cisco to create a
technologically advanced network system that is flexible and will facilitate
Carrier1's migration to a single integrated data-based transmission platform for
both voice and data traffic when proven technology becomes commercially
available.


    EXISTING AND PLANNED TRAFFIC TERMINATION ARRANGEMENTS

    VOICE TRAFFIC.  Carrier1 carries voice traffic to any destination in the
world, either directly or through "refile" or "resale" agreements with other
carriers who have a local point of presence and an interconnection agreement
with the relevant incumbent telephone operator.

    As of March 31, 1999, Carrier1 had entered into interconnection arrangements
to provide for the local termination of its voice traffic with carriers in
Austria, Denmark, Germany, The Netherlands, Sweden, Switzerland, the United
Kingdom, and the United States. As of March 31, 1999, Carrier1 has implemented
interconnection arrangements in Austria, Germany, Switzerland, the United
Kingdom and the United States and is in the process of implementing these
arrangements in these other countries. Since March 31, 1999, Carrier1 has signed
interconnection agreements with Tele Danmark in Denmark, Telecom Italia in Italy
and Telia in Sweden and has implemented its interconnection agreements in The
Netherlands. Carrier1 initiated interconnection negotiations with Belgacom in
Belgium, France Telecom in France and Telecom Eireann in Ireland in early 1999.
By December 1999, Carrier1 intends to have

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implemented direct operating agreements with local carriers for termination of
voice traffic in a number of emerging markets.

    Most refilers currently operate out of London or New York, so that
Carrier1's refiled traffic is rerouted to London or New York and from there is
carried to its termination point. As of March 31, 1999, Carrier1 had resale
agreements in Austria, France, Germany, The Netherlands and Switzerland.


    DATA TERMINATION.  Data termination is effected free-of-charge through
peering and for a fee through transit arrangements. As of March 31, 1999, in the
United States, Carrier1 has peering arrangements with Epoch Networks and PSINet,
and has, transit agreements with UUNet and GTE Internetworking. In Europe,
Carrier1 has, peering arrangements with a number of ISPs and a transit agreement
with Ebone. Carrier1 will continue to seek additional peering arrangements.


OPERATIONS

    NETWORK IMPLEMENTATION AND OPERATION


    Network engineering, technical operation and maintenance and repair have
been handled exclusively by Nortel in connection with the voice overlay of the
network, and were handled exclusively by Cisco in connection with the data
overlay of the network. Carrier1 will continue to work closely with Nortel and
Cisco to ensure future implementation milestones are met, and that the quality
and performance of the network meet certain Carrier1-established benchmarks. The
initial outsourcing of the design, installation and technical operation of its
network allowed Carrier1 to maintain low overhead costs during its initial
operations period.



    The voice and data network operating systems allow Carrier1 to use advanced
software to maximize the efficient operation of the network, including managing
the flow of voice and data traffic on a daily basis and identifying the precise
location of faults. These systems are also sufficiently flexible to allow
Carrier1 to migrate to more advanced technological applications as they become
commercially feasible.


    Carrier1 has assumed the technical operation of the network (other than
basic equipment servicing) from Cisco, and intends to do so from Nortel by
mid-1999, so that Carrier1 can control all the customer-related functions of the
business. Until then, Carrier1's personnel will work side by side with Nortel
personnel to receive on-site training. Carrier1 expects that this training will
permit a smooth transition from outsourcing to insourcing of the network's
operational functions and reduce the risks of disruption due to the shift in
responsibilities. Carrier1 expects to continue to contract with Nortel and Cisco
for the design and installation of switches and routers. A small team of
operations staff will manage the future planning and architecture of the
network.


    Carrier1 has a network operations center in London from which it operates
the voice and data network. Carrier1 believes that a centralized network
operations center enables it to identify overloaded or malfunctioning circuits
and reroute traffic much more quickly than if the network were controlled by
separate network operations centers from different countries.


    Recently, Carrier1 has bought the "Qualiview" system from ECI, which is
designed to allow it to measure call answer rate, post dial delay and echo on a
per destination basis for each party that terminates traffic for Carrier1.
Carrier1 has implemented the first part of this system and expects the rest of
this system to be implemented in the second quarter of 1999.

    THIRD-PARTY TURNKEY CONTRACTS

    THE NORTEL CONTRACT.  Carrier1 entered into a turnkey agreement with Nortel
in May 1998, under which Nortel has responsibility for the design, installation,
technical operation, maintenance and repair of its voice network switches,
including the provisioning of equipment, software and services. Nortel has
committed to a 12-month warranty of any defective equipment or software it may
provide. Nortel has also

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agreed to supply replacement parts for equipment and software support (including
upgrades) for a period of ten years following the date of delivery of such
equipment or software. Carrier1, in turn, has agreed to purchase a certain
volume of services and equipment from Nortel, and is subject to surcharges if it
fails to meet such volume thresholds for reasons other than Nortel's material
breach. Carrier1 has agreed to continue to use Nortel's network operation and
management services up to July 1999, by which time Carrier1 will assume full
operational control of these functions. The turnkey contract contains
limitations on Nortel's total liability.


    THE CISCO CONTRACT.  Carrier1 entered into a turnkey agreement with Cisco
(the "Cisco Agreement") in June 1998, for the design, installation, operation,
maintenance and repair of its data network routers. Cisco has provided a 90-day
warranty on the software and hardware it provides to Carrier1. Cisco will
provide technical support for its standard software for a period of three years
following the latest revision of that software. Cisco's liability under the
agreement (other than for personal injury) is limited to the amounts paid under
the agreement to Cisco in the six-month period prior to the event giving rise to
the liability.


    CUSTOMER SUPPORT

    An essential component of Carrier1's business strategy is to provide a level
of customer support above that which is currently available in the wholesale
telecommunications markets of Europe.


    All customer service orders received by the local sales forces are reported
to the central order desk at Carrier1's network operations center which then
logs the order into Carrier1's computer system and directs the order to the
voice or data team, as applicable. The central order desk also tracks the status
of an order during implementation. Carrier1 has automated its operational
workflows so that the status of customer order implementation, traffic faults,
repair histories and other customer-related information is accessible, on-line,
by any employee of Carrier1 at any time. Carrier1 believes that the internal
visibility created by the on-line availability to any Carrier1 employee of all
customer-related information enhances the general monitoring and management of
the customer relationship and facilitates informed and timely responses to
customers' service needs or problems. Furthermore, by tracking on-line all
aspects of a customer's history from the customer's first call through the term
of the relationship, Carrier1 optimizes its ability to provide follow-up and
proactive advice to its customers.



    The voice and data operations teams at Carrier1's network operations center
and the in-country operations support team manage the local point of presence
locations, local installation and local support, and work together to implement
a customer's order. The in-country operations and sales teams provide a customer
with local language support and quick access and response to customer orders and
other service needs. A help desk in London serves as the first place to which
customer inquiries are directed. The help desk is open 24 hours a day, 365 days
a year. It not only manages customer inquiries but is the first place to which
customer problems are reported and, from there, internally directed for
resolution. Customers may call the help desk at any time to receive a status
report regarding their request or problem.



    In addition to the minimum service level guarantees contained in Carrier1's
voice and data service contracts, Carrier1 also guarantees response times to
customer requests within hours, and repair times within one day of the fault
being reported.


    INFORMATION AND BILLING SYSTEMS


    Unburdened by legacy systems, Carrier1 has obtained and installed advanced
IT systems tailored to providing wholesale voice and data services. Carrier1 has
developed its own system to enable it to determine least cost routing on a
real-time basis, allowing it to maximize margins within the constraints of the
network. In order to identify the least cost route for voice traffic at any
given time, the system takes into account all costs on a given route, refile or
resale possibilities and their constraints, transmission costs and constraints
per route, as well as other cost elements. Routing information is updated daily
and takes


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into account the prior day's actual costs rather than hypothetical forward
costs. Among other things Carrier1's systems are designed to facilitate on a
real-time basis

    - swift and efficient order management,

    - service provisioning,

    - customer-responsive traffic fault management,

    - billing,

    - general management of the customer service process and

    - compliance with Carrier1's performance level guarantees.

    Carrier1 currently uses software programs developed by third parties as its
primary office and information management systems. These programs have been
tailored, however, to Carrier1's particular specifications.


    As part of its strategy of focusing on the specific needs of new entrants
into the European telecommunications market, Carrier1's billing system
emphasizes flexibility and customization. Customers may be billed in the
currency of their choice, and may have their bills broken down by country, site,
or other call detail records. Carrier1 uses International Computers Limited's
("ICL") SIMS and Prospero billing systems software. Carrier1 initially
outsourced the running of such billing programs to ICL, but expects to bring the
running of such programs in-house by June 1999. Carrier1's billing system
analyzes Carrier1's traffic, revenues and margins by customer and by route,
which is an important cost management tool for Carrier1. Carrier1 expects that
by April 1999 its customers will be able to obtain call detail records and other
information through an on-line billing information inquiry function. Carrier1
plans to maintain separate billing modules for voice and data services, although
customers utilizing both services may be billed on one invoice if desired.


CUSTOMERS

    Focusing primarily on European customers and North American customers with
European connectivity needs, Carrier1 targets the following categories of
customers:

    - COMPETITIVE FIXED-LINE OPERATORS. This category includes fixed-line
      operators that compete with the incumbent telephone operators. These
      operators typically desire to outsource their international and, from time
      to time, their national long distance traffic.

    - OTHER NON-INCUMBENT CARRIERS. This category includes operators with
      international infrastructure, who select Carrier1 to carry overflow excess
      traffic and to carry traffic to select, low-price destinations.

    - WIRELESS OPERATORS. Wireless operators frequently outsource much of their
      international and national long distance traffic.


    - ISPS AND REGIONAL AND SPECIALIST PROVIDERS. As demand for Internet
      services grows in Europe, ISPs are increasingly requiring low-cost
      transmission and interconnection capabilities from wholesale carriers.
      Many ISPs do not own or operate their own transmission capacity. Cable
      television companies, satellite resellers and metropolitan area network
      providers are also demanding increasing amounts of low-cost data services.


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<PAGE>
    - RESELLERS. This category includes switchless resellers, a group that has
      been rapidly growing in the United Kingdom and Germany in recent years.
      Resellers generally outsource their international and, from time to time,
      national long distance traffic.


    - CONSORTIA. A number of groups have formed buying consortia to pool traffic
      volume in order to obtain higher discounts from carriers. For example, a
      group of European multinational entities have combined to form the
      European VPN Users Association's Ventures Group to acquire voice services
      and currently split their traffic among incumbent telephone operators and
      incumbents' alliances. Carrier1 will target buying consortia and will also
      seek to provide its services to research consortia. The research consortia
      represent an important part of the data market.


    - MULTI-NATIONAL CORPORATIONS. Increasingly, multi-national corporations are
      seeking wholesale telecommunications services to reduce their costs or as
      a component of their own value-added services such as frame relay.
      Although multi-national corporations are not a primary customer group for
      Carrier1 due to their relatively high customer service demands, Carrier1
      offers capacity to multi-national corporations on a wholesale basis.

    - INCUMBENTS AND THEIR ALLIANCES. A number of incumbent telephone operators
      and their affiliated alliances use wholesale carriers to carry excess
      traffic generated by bottlenecks in their network or to terminate traffic
      to certain locations at lower rates than their negotiated settlement
      rates.


    Carrier1 uses a credit screening process to evaluate potential new
customers. In performing its credit analysis, Carrier1 relies primarily on
internal assessments of its exposure, based on the costs of terminating
international traffic in certain countries and the capacity requested by the
proposed carrier or service provider, as well as references provided by the
potential customer. Carrier1 currently depends on a small number of significant
customers for its revenues. During the period from Inception to December 31,
1998, Carrier1 earned 69% of its revenues from three major customers. These
three customers, Interoute Telecommunications (UK) Limited, WorldCom
Telecommunications Services GmbH and STAR Telecommunications Deutschland GmbH,
accounted for 46%, 13% and 10%, respectively, of Carrier1's total revenues
during that period. One new customer, Mobilcom AG, may account for up to 30% of
Carrier1's revenues in the near term. Carrier1's agreement with MobilCom is for
an initial term of twelve months, ending December 2, 1999, and will be renewed
automatically unless cancelled. The agreement employs usage-based pricing and
does not provide for minimum volume commitments by MobilCom.


SALES

    Carrier1 has an internal sales force focused on marketing services to
wholesale customers. Carrier1 currently has sales representatives in Amsterdam,
Frankfurt, London, New York, Milan, Paris, Stockholm and Zurich. The heads of
these sales offices have extensive telecommunications-related marketing and
sales experience, as well as strong customer relationships, in the geographic
markets in which they are located. Carrier1 intends to hire additional sales
executives as it increases the number of its offices and expands its existing
sales efforts. Carrier1 will continue to seek personnel with a high degree of
experience in and knowledge of the local telecommunications markets in which
they will be working.

    Currently, the Frankfurt sales office functions as the regional head office
covering German-speaking Europe and Eastern Europe; the Paris sales office
functions as the regional head office for France; New York functions as the
regional sales center for North America; Stockholm functions as the regional
sales center for Denmark, Finland, Norway and Sweden; Milan functions as the
regional sales center for Italy; the London sales office functions as the
regional head office for all English-speaking countries in Europe; and the
Amsterdam sales office functions as the regional head office for the Benelux
countries. Customers who do not, for one reason or another, fit within a
particular region are covered by the Zurich sales office.

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<PAGE>
Carrier1 expects its regional strategy will permit it to keep operating costs
down until traffic volumes in various other locations in Europe are large enough
to justify establishing sales offices in such locations.


    Carrier1 also has sales people specializing in data who work out of the
London, Frankfurt, Paris and Amsterdam sales offices. These data specialists
focus on marketing to ISPs and other customers whose needs are primarily or
exclusively data-oriented. They also work with other members of the sales force
in marketing a package of voice and data services as required by customer
demand.


    Carrier1 currently has a limited number of customers, enabling it to provide
each prospective or actual customer with personalized account management.
Furthermore, in comparison to the mass retail market, the wholesale
telecommunications market has a relatively small number of customers. Carrier1
expects that this market characteristic will permit it to continue to provide
personalized account management even as the number of its customers continues to
grow.

PRICING


    Carrier1's agreements with its voice customers are typically for an initial
term of twelve months and will be renewed automatically unless cancelled. They
employ usage-based pricing and do not provide for minimum volume commitments by
the customer. Carrier1 expects to generate a steady stream of voice traffic by
providing high-quality service and superior customer support. Carrier1's data
services are charged, depending on service type, either at a flat monthly rate,
regardless of usage, based on the line speed and level of performance made
available to the customer, or on a usage basis, with no minimum volume
commitment by the customer. Initially, the majority of Carrier1's data contracts
were usage-based. Since March 31, 1999, Carrier1 has migrated to offering
usage-based data pricing only in combination with data contracts that have a
fee-based component that guarantees minimum revenue, in order to encourage usage
of its network services by its data customers. Carrier1's agreements with its
data customers are generally for a minimum term of twelve months, although
Carrier1 may seek minimum terms of two years or more for agreements providing
for higher line speeds.



    Currently, voice and data services are both priced competitively and
Carrier1 emphasizes quality and customer support, rather than offering the
lowest prices in the market. The rates charged to voice and data customers are
subject to change from time to time. Carrier1 will also vary pricing on its
routes as a traffic management tool. Carrier1 initially priced its data services
at a discount to its competitors to build rapidly its customer base. Carrier1
expects to experience declining revenue per billable minute for voice traffic
and declining revenue per Mb for data traffic, in part as a result of increasing
competition. Carrier1 believes, however, that the impact on its results of
operations from such price decreases will be at least partially offset by
decreases in its cost of providing services and increases in its voice and data
traffic volumes.


COMPETITION


    The European telecommunications industry is highly competitive, and the
liberalization it is currently undergoing is rendering it increasingly more so.
The opening of the market to new telecommunications service providers, combined
with technological advances that greatly augment the transmission capacity of
circuits at a relatively small incremental cost, has resulted in significant
reductions in retail and wholesale prices for voice services. Prices declined
significantly during 1998, and Carrier1 expects prices to continue to decline.
While decreasing prices are fueling growing demand for bandwidth, they are also
narrowing gross profit margins on long distance voice traffic. Carrier1's
ability to compete successfully in this environment will be highly dependent on
its ability to generate high traffic volumes from its customers while keeping
its costs of services low. Prices for data services remain relatively high in
Europe. However, the United States market for data services has been
experiencing downward pressure on prices, and Carrier1 expects comparable price
decreases in the European data market over the next few years as competition
increases. As prices for data services decline, Carrier1's ability to compete
successfully in the


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data market will be highly dependent on its ability to attract and retain enough
customers and keep its cost base low.


    In voice services, Carrier1 has two main categories of competitors. The
first is the group of large established carriers, consisting of incumbent
telephone operators and affiliated companies, that offer a wide range of
wholesale services in addition to their retail services. This group includes
AT&T, British Telecom, the KPN Telecom/Qwest Communications International Inc.
alliance, Cable & Wireless, Global One (a joint venture of Deutsche Telekom,
France Telecom and Sprint Corp.), MCI WorldCom, Inc., Tele Danmark A/S,
Teleglobe Inc., Unisource N.V. and Telecom Italia S.P.A. The second category
comprises new entrants to the telecommunications market that provide wholesale
services. This group includes Pacific Gateway Exchange Inc., FaciliCom
International, Inc., Hermes, STAR Telecommunications, Inc., Viatel, Telegroup
Inc., and RSL Communications Ltd. Hermes owns 75% of Ebone, a large European
backbone provider.


    In data services, Carrier1's main competitors are Ebone, UUNet and Qwest
Communications International Inc., all of which have an established customer
base and either a significant European infrastructure or strong connectivity to
the United States through various peering arrangements. Carrier1 believes that,
if the quality of the service is consistently high, data customers will
typically renew their contracts because it is costly and technically burdensome
to switch carriers.


    Carrier1 is a wholesale carrier and, while it does not compete directly with
the incumbent telephone operators or other carriers for end-users, it is
entering a rapidly developing market in which companies traditionally focused on
the retail sector are beginning to sell to the wholesale market and owners of
infrastructure are beginning to provide services as well as capacity at both the
retail and wholesale level. In addition, many of Carrier1's competitors are
larger enterprises with greater financial resources than Carrier1, and
accordingly may be able to deploy more extensive networks or may be better able
to withstand pricing and other market pressures.


    A number of Carrier1's competitors are devoting significant resources to the
provision of European telecommunications services to carriers and other service
providers, including through the construction of their own networks. Those
wholesale providers that own a European infrastructure will benefit from a lower
cost base than Carrier1, at least initially, and it will be essential for
Carrier1 to lower its cost base as quickly as possible to compete effectively
with them. Furthermore, those wholesale carriers that have successfully
negotiated interconnection agreements with the relevant incumbent telephone
operators or peering arrangements with other Internet backbone providers, as
applicable, will also have a lower cost structure than Carrier1 and will,
therefore, be in a better position to compete on the basis of price than
Carrier1, until Carrier1 enters into such agreements.



    Carrier1 competes with a number of incumbent telephone operators. In many
European countries, the incumbent telephone operator controls access to local
networks and has significant operational economies, including a large national
network, and existing operating agreements with other incumbent telephone
operators. Moreover, incumbent telephone operators generally have close ties
with national regulatory authorities, which have, in some instances, shown
reluctance to adopt policies and grant regulatory approvals that would result in
increased competition for the local incumbent telephone operator. In addition,
many of Carrier1's non-incumbent competitors are associated with incumbent
telephone operators and such incumbents may be more likely to provide
transmission capacity on favorable terms and direct excess traffic to their
related carriers than to Carrier1. However, Carrier1 believes that such
affiliations may be more of a hindrance than a benefit. The incumbent telephone
operators are more focused and dependent on traditionally structured retail
services, and are less responsive to the dynamics of the wholesale market and
the growth of the data market. Furthermore, the incumbent telephone operators
are resisting the new pricing and services rationales created by low cost
alternative infrastructure and European Commission mandated changes in
interconnection tariffs as these threaten to accelerate the collapse of
traditional ARM based services which have historically been a major


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source of profitability for the incumbent telephone operators. Therefore, while
the incumbent telephone operators cannot afford to completely ignore the
development of new service markets, they may perceive a short term interest in
slowing the pace of their growth, with the result of incumbent telephone
operators treating their affiliates more as competitors than as partners.

    Other factors contributing to the competitiveness of the wholesale carrier
market are:

    - Basic voice carrier services are not highly differentiated, and switching
      carriers is not costly. Voice customers can easily redirect their traffic
      to another carrier, and certain customers may do so on the basis of even
      small differences in price.

    - Network buildout costs are high, creating an incentive for wholesale
      carriers that have built their network to lower prices so as to increase
      volume and maximize utilization rates.

    - New networks are being built to provide significant additional capacity,
      creating further downward pressure on prices.

    Many of Carrier1's competitors, however, are also potential customers. For
example, carriers with their own infrastructure may have excess traffic that
wholesale carriers such as Carrier1 can carry. Furthermore, Carrier1 may, in
certain instances, be able to provide less expensive routing for certain
destinations and may therefore carry traffic over those particular routes. It is
customary industry practice for carriers and other telecommunications service
providers to use a number of wholesale voice service providers. Accordingly,
Carrier1 need not be a customer's sole wholesale voice carrier but may be one of
three or four selected.

GOVERNMENT REGULATION

    The following discussion summarizes the material aspects of the regulatory
frameworks in certain regions in which Carrier1 currently operates or plans to
operate in the near future. This discussion is intended to provide a general
overview of the more relevant regulations and Carrier1's current regulatory
posture in the most significant jurisdictions in which Carrier1 operates and
expects to operate. It is not intended as a detailed description of the entire
regulatory framework applicable to Carrier1.

    OVERVIEW

    Increasing regulatory liberalization in many countries' telecommunications
markets now permits more flexibility in the way Carrier1 can provide
infrastructure and services to its customers. The recent steps of the European
Union to implement full liberalization, as well as the World Trade Organization
(the "WTO") Basic Telecom Agreement (the "WTO Agreement"), have significantly
reduced most if not all regulatory barriers to entry in the markets in which
Carrier1 intends to operate. However, national regulatory frameworks within the
European Union that are fully consistent with the policies and requirements of
the European Union and the WTO have only recently been, or are still being, put
in place in many member states.

    Various directorates of the European Commission, including Directorate
General ("DG") XIII (telecommunications and information services) and DG IV
(competition), have had an active role in overseeing the implementation of
recently adopted European Union directives. These directorates have, on their
own initiative or upon formal or informal complaint by interested parties,
sought to ensure consistent implementation and interpretation of various key
European Union directives, including in particular those relating to licensing
and interconnection.

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    The principal telecommunications operators in many European Union member
states, including in particular the United Kingdom and most Scandinavian
countries, have generally accepted market liberalization and have acted
accordingly in their dealings with new entrants. In other markets, Carrier1 and
other new entrants face less open and independent regulatory environments and
hence more protracted and difficult procedures to obtain licenses and negotiate
interconnection agreements. Carrier1 believes that the current overall
regulatory climate in the European Union is favorable to development of new
infrastructure and services by new entrants, and that potential restrictions on
its operations will become less onerous as national regulatory frameworks within
the European Union become more uniform and begin to converge with those in the
countries with fully liberalized regulatory policies such as the United States.
However, Carrier1 is unable to predict with certainty the precise impact of
regulatory requirements and restrictions on its implementation of its business
strategy or on its financial performance.

    WTO AGREEMENT

    The regulation of the European Union telecommunications industry is subject
to certain multilateral trade rules and regulations. Under the WTO Agreement,
concluded on February 15, 1997, 69 countries comprising more than 90% of the
global market for basic telecommunications services agreed to permit competition
from foreign carriers and adopt regulatory measures designed to protect
telecommunications providers against anticompetitive behavior by incumbent
telephone operators. In addition, 59 of these countries have subscribed to
specific pro-competitive regulatory principles.

    The WTO Agreement became effective on February 5, 1997 and for most
signatory countries (including ten European Union member states) the commitments
took effect on January 1, 1998. Although there may be substantial implementation
delays, Carrier1 believes that the WTO Agreement will increase opportunities for
Carrier1 and its competitors. However, the precise scope and timing of the
implementations of the WTO Agreement remain uncertain and there can be no
assurance that the WTO Agreement will result in beneficial regulatory
liberalization.

    EUROPEAN UNION

    In an effort to promote competition and efficiency in the European Union
telecommunications market, the European Commission and the European Council have
in recent years issued a series of directives establishing basic principles for
the liberalization of such market. The general framework for this liberalized
environment has been set out in the European Commission's Services Directive,
adopted in 1990, and its subsequent amendments, including the Full Competition
Directive, adopted in March 1996. These directives require most European Union
member states to permit competition in all telecommunications services, and had
set January 1, 1998 as the date by which all restrictions on the provision of
telecommunications services and telecommunications infrastructure were to be
removed. These directives have been supplemented by various harmonizing
directives, including primarily the Licensing Directive and the Interconnection
Directive, adopted in 1997.

    The Licensing Directive established a common framework for the granting of
authorizations and licenses related to telecommunications services. It permits
European Union member states to establish different categories of licenses for
providers of infrastructure and services, but requires the overall scheme to be
transparent and non-discriminatory. The Interconnection Directive requires
European Union member states to remove restrictions preventing negotiation of
interconnection agreements, ensure that interconnection requirements are
non-discriminatory and transparent, and ensure adequate and efficient
interconnection for public telecommunications networks and publicly available
telecommunications services. It also requires that interconnection be cost-based
and supported by a cost accounting system that telecommunications operators with
significant market power are expected to put in place under the supervision of
national regulatory agencies.

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    In October 1997, the European Commission issued a consultative document
supporting the imple-
mentation of long run incremental cost ("LRIC") principles as a basis for
interconnection pricing. This document also sets forth interconnection pricing
benchmarks reflecting current interconnection agreements in European Union
member states. The European Commission believes such benchmarks should be relied
upon pending the adoption of accounting systems and interconnection rates based
on LRIC principles. These guidelines have become an important reference point in
commercial negotiations between new entrants and incumbent telephone operators.

    The European Commission's consultative paper also proposes that European
Union member states permit cross-border interconnection between a national
telecommunications operator and an operator that does not have a local point of
presence and that is established and licensed in another member state on the
basis of interconnection arrangements that do not discriminate between
cross-border and national operators. Carrier1 believes that the European
Commission's stance with respect to cross-border interconnection may not be
sufficiently supported by some national regulatory agencies as it is not yet set
forth in a binding directive. Nevertheless, Carrier1 may seek cross-border
interconnection in those countries in which it does not have a point of
presence. However, there can be no assurance as to when or if Carrier1 will be
successful as no operational arrangements have been made or other steps taken to
implement cross-border interconnection.


    Several European Union member states have chosen to apply the provisions of
the Interconnection Directive within their jurisdictions in such ways as to give
more favorable treatment to infrastructure providers and network operators than
to carriers and resellers that have made no infrastructure investment. Such
distinctions must be objectively justified on the grounds of the type of
interconnection provided or because of relevant licensing conditions. The
Licensing Directive does not provide a clear definition of an infrastructure
investment, and many European Union member states have adopted inconsistent
approaches with respect to the level and type of infrastructure investment
required to justify differences in interconnection charges. While Carrier1
believes that the European Commission will seek to minimize these disparities in
national interconnection policies, there can be no assurance that these
disparities can be eliminated or significantly reduced or that any such
differences in regulatory treatment will not have a material adverse effect on
Carrier1. To the extent incumbent telephone operators deny or delay granting
Carrier1 interconnection, even if only for a limited period of time, in any of
the countries in which Carrier1 has or will have points of presence, Carrier1
will be forced to terminate traffic through refile or resale agreements with
other carriers, resulting in higher costs. Furthermore, if interconnection is
not granted at the most competitive rate (i.e., the rate for operators and
infrastructure providers), Carrier1's termination costs will be higher than
those of competitors which have implemented such interconnect agreements.


    REGULATORY STATUS

    The following discussion summarizes Carrier1's assessment of the regulatory
situation in the major markets in which it expects to operate in the next
several years.

    UNITED KINGDOM.  The Telecommunications Act 1984 provides a licensing and
regulatory framework for telecommunications activities in the United Kingdom.
The United Kingdom has already liberalized its market to meet or even exceed the
requirements of the Full Competition Directive, and most restrictions on
competition have been removed in practice as well as in law.

    Carrier1 currently has been granted an international simple voice services
resale license and an international facilities license that allows it to own
indefeasible rights of use and to lay cable for international services. Carrier1
will not need any additional licenses as long as it does not connect end-users
systems directly to its network. Carrier1 has obtained a switched access number
which has been implemented with British Telecom. This access number enables
Carrier1 to allow switchless resellers to offer switched access services
directly to their customers in the United Kingdom.

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<PAGE>
    In the United Kingdom, entities with "relevant connectable systems" status
are entitled to request and receive interconnection from those operators that
have been determined to be "well established operators." British Telecom and
Kingston Communications International Ltd. have been so determined for all
services and Cable & Wireless has been so determined in respect of international
services on virtually all routes. Carrier1 currently has implemented
interconnection agreements with Cable & Wireless and British Telecom. In
addition, Carrier1 has entered into interconnection agreements with other
telecommunications operators in the United Kingdom to route traffic to locations
not directly served by Carrier1.

    The current liberal regulatory climate in the United Kingdom has encouraged
the rapid development of new operators that are available to interconnect with
Carrier1 or to be served by Carrier1 as customers for its wholesale service
offerings. London, along with New York, has become one of the major
international centers for refiling of traffic among international
telecommunications service providers. Overall, Carrier1 has not encountered
significant interconnection barriers in the United Kingdom.

    UNITED STATES.  In June 1998, Carrier1 obtained a Section 214 authorization
to provide international telecommunications services to all locations around the
world. Carrier1 will be subject only to various reporting obligations with
respect to its current operations in the United States.

    Under the terms of recent Federal Communications Commission (the "FCC")
orders relating to international settlement rates, the terms of its Section 214
authorization and the WTO Agreement, Carrier1 will be expected to settle its
international switched traffic at or below the level of the international rate
benchmarks prescribed by the FCC. It would also have to obtain prior FCC
approval to resell leased lines in any country in which it might operate with an
affiliated carrier with market power. However, Carrier1 does not expect that any
current or currently anticipated FCC regulatory requirement would materially
limit its commercial or operational flexibility.

    The FCC has taken an active role in opening competition on an international
basis and has been involved in a longstanding effort to lower international
accounting rates on a world-wide basis. Although the FCC has implemented the WTO
Agreement and no longer bases its international licensing determinations
specifically on whether international markets are open on a fully reciprocal and
comparable basis to U.S. telecommunications operators, it continues to monitor
competitive developments in international markets in order to assess whether any
restrictive practices with respect to international service arrangements or
rates might have an adverse or distorting impact on competition in the U.S.
domestic telecommunications market. In addition, the FCC as well as various
executive branch agencies of the U.S. government have taken an active posture
with respect to the full implementation of market-opening commitments made in
connection with the WTO Agreement, and have from time to time taken positions
against potential restrictive regulatory practices by national regulators or
operators in the European countries in which Carrier1 intends to operate.

    Carrier1 has experienced no difficulties in negotiating interconnection
agreements with U.S.-based telecommunications operators. These arrangements
permit Carrier1 to extend its services into the U.S. domestic market as well as
to terminate traffic worldwide. In addition, refiling arrangements available in
the United States can often be a very cost-effective basis for terminating
traffic in European Union markets that are not directly served by Carrier1's own
infrastructure. Depending on market conditions, such arrangements represent a
viable alternative to refiling through the United Kingdom.

    GERMANY.  The German Telecommunications Act of July 25, 1996 provided for
the liberalization of all telecommunications activities by January 1, 1998. The
German Telecommunications Act has been complemented by several ordinances
concerning, among other things, license fees, rate regulation, interconnection,
universal service, frequencies and customer protection. The German
telecommunications sector is currently overseen by a new Regulatory Authority
for Telecommunications and Post that operates under the aegis of the Ministry of
Economics and has taken over the regulatory responsibilities of the now
disbanded Ministry of Post and Telecommunications.

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<PAGE>
    Under the German Telecommunications Act, licenses can be issued for
different types of infrastructure as well as for the provision of services based
on transmission lines provided by other service providers. Carrier1 has been
issued a nationwide Class 4 license for the provision of voice telephony
services and a Class 3 infrastructure license to construct fiber optic cables.
Carrier1 has obtained amendments to its infrastructure licenses to authorize the
geographic extension of its network. Carrier1 does not anticipate any difficulty
in obtaining any further required amendments. On October 30, 1998, the German
regulator ruled, in a case filed by Carrier1 against Deutsche Telekom, that
Deutsche Telekom had to interconnect with Carrier1 at the two points of
interconnect requested by Carrier1 within three months after the ruling. This
ruling is currently being implemented by both parties and is based on a
condition that Carrier1 will be installing an additional 11 points of
interconnection with Deutsche Telekom when it deploys its German Network by the
end of 1999. Carrier1 recently signed an interconnection agreement with Deutsche
Telekom that adds ten points of interconnection to the 13 points that Carrier1
has already arranged. Both parties are working to implement this interconnection
agreement by the first quarter of 2000. See "--Network--Planned Network
Deployment--The German Network." In the event that Carrier1 does not install
such additional points of interconnection anticipated by the ruling and
Carrier1's business plans, the pricing of its interconnection arrangements with
Deutsche Telekom may have to be renegotiated. There can be no assurance that any
new pricing terms would be as favorable to Carrier1 as those provided by the
ruling. Furthermore, the German regulator recently concluded a public
consultation indicating that Deutsche Telekom may charge a higher interconnect
rate to those operators who only interconnect at one point of interconnect. This
conclusion, however, still needs to be implemented into law.

    Carrier1 has initiated discussions with Deutsche Telekom relating to the
installments of its points of interconnection. Though Carrier1 believes that
these discussions are generally proceeding in a satisfactory fashion, there have
been a number of disputes over the availability, and timing of delivery, of
interconnection capabilities requested by Carrier1. Though Carrier1 intends to
pursue such disputes with Deutsche Telekom and the German regulator, it does not
currently anticipate that there is likely to be any significant adverse impact
on its plans to provide service in Germany in accordance with its business
plans. Carrier1 has obtained a switched access number and has implemented it
with Deutsche Telekom. This access number enables Carrier1 to allow switchless
resellers to offer switched access services directly to their customers in
Germany.

    FRANCE.  In July 1996, legislation was enacted providing for the
liberalization of all telecommunications activities in France by January 1,
1998. The establishment and operation of public telecommunications networks and
the provision of voice telephony services are subject to individual licenses
granted by the Minister in charge of telecommunications upon recommendation of
the Autorite de Regulation des Telecommunications ("ART"), France's new
independent regulatory agency.

    Carrier1 has been confirmed to receive an L-33.1 license (governing public
telecommunications network operators) and an L-34.1 license (governing voice
telephony providers). The interconnection tariffs of France Telecom, which have
been officially approved by the ART, provide substantially more favorable
interconnection rates for public telecommunications network operators than for
voice telephony providers. Telephony providers are charged interconnection rates
that can be as much as 30% higher than rates charged to public
telecommunications network operators. An L-34.1 license allows an operator to
terminate traffic nationwide via interconnect only if it connects in all 18
interconnect regions, whereas an L-33.1 license allows an operator to terminate
traffic nationwide via interconnect at only one point.

    The ART and other French regulatory authorities have not published precise
guidelines concerning what type of infrastructure investment is required as a
basis for grant of an L-33.1 infrastructure license. In recent decisions L-33.1
licenses have been granted to operators that owned or planned to own switches
and to acquire dark fiber, without laying down cables themselves. Carrier1 plans
to make a comparable investment in France, and thus it expects to be granted
both L-33.1 and L-34.1 licenses. Failure by Carrier1 to obtain an L-33.1 license
could impede its ability to achieve a reasonable, cost-efficient interconnection

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<PAGE>
arrangement with France Telecom, which in turn could have a material adverse
effect on Carrier1's ability to provide terminating services into and through
France on a cost-effective basis.

    Carrier1 believes that the dual pricing system engaged in by France Telecom
is discriminatory and not founded on a cost-based differentiation and thus
violates the terms of the WTO Agreement as well as provisions of various
relevant European Union directives. Nevertheless, any process initiated by
Carrier1 against France Telecom's practices with the European Union or the WTO,
even if successful, might well be costly and time consuming, and Carrier1 is not
able to predict with certainty the timing and eventual resolution of any legal
challenge over interconnection rates.

    Carrier1 initiated interconnection negotiations with France Telecom in early
1999. In a recent decision, ART has ruled that interconnection agreements have
to be implemented within nine months after start of negotiations and that
negotiations can start after the application for a license has been submitted,
but before a license has been granted. The interconnection agreement, however,
can only be implemented after grant of the license.

    In France, the ART implements an extra charge (cost per minute) to finance
the cost of a universal service fund. The total amount of this universal service
fund was $1 billion for 1998 and has been challenged by new entrants in the
French market, who have filed a complaint with DG IV, the European Union's
competition directorate. Carrier1 is unable to estimate at this time the impact
of the proposed universal service program if implemented on its operating
margins. Carrier1 intends to apply to the French regulator to obtain a switched
access number in order to enable Carrier1 to allow switchless resellers to offer
switched access services directly to their customers in France.

    BELGIUM.  In December 1997, the Belgian parliament provided for full
liberalization of the provision of telecommunications services. The
Telecommunications Act and secondary legislation are not yet complete.

    Under the current licensing scheme, applicants for a telecommunications
network operator license such as Carrier1 must agree to make a minimum amount of
infrastructure investment or install a minimum amount of fiber optic capacity
within three years, as well as make a contribution to the advancement of
technological processes by investing an amount equal to 1% of net revenue to
fund research and development activities. Carrier1 has filed an application to
become a network operator with respect to which regulatory action by the Belgian
national regulator, the Belgian Institute for Postal Services and
Telecommunications ("BIPT"), is expected by July 1999. As Carrier1 plans to
acquire dark fiber in Belgium, it expects to be granted an infrastructure
license.

    Carrier1 has initiated interconnection negotiations with Belgacom S.A.,
Belgium's incumbent telephone operator. The interconnection tariffs of Belgacom
provide more favorable rates for infrastructure providers and network operators
than for switch-based carriers and resellers. Carrier1 expects to qualify for
these more favorable rates. However, the outcome of Carrier1's efforts with
respect to its interconnection arrangements may depend in part upon
deliberations concerning the requirements for a network operator license as well
as ongoing Belgian regulatory determinations.

    The Belgian telecommunications law also provided for the establishment of a
universal service fund, to be managed by BIPT, to which operators would be
required to contribute in proportion to their revenues from the Belgian market.
However, the fund is not to be activated before the year 2000, by which time the
BIPT is required to determine the aggregate payment to support universal
service. Carrier1 is unable to estimate at this time the impact of any potential
universal service payments on the overall cost of terminating its customers'
calls in Belgium.

    ITALY.  In 1997, Italian authorities enacted a legislative framework for the
full liberalization of telecommunications services by January 1, 1998. This
framework has yet to be implemented by a number of necessary decrees. Major
uncertainties remain with regard to the rules applicable to interconnection. No

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<PAGE>
assurance can be provided as to the timing or manner in which Carrier1 will be
able to benefit from full liberalization in Italy. Carrier1 has obtained both
infrastructure and service licenses.

    In August 1998, Telecom Italia published its Reference Interconnect Offer
(the "RIO"), which has been amended recently due to decisions by the Italian
regulator. The RIO now allows interconnection at one point of interconnect and
brought interconnection rates down to a level much closer to the European Union
benchmarks. Carrier1 has signed an interconnection agreement with Telecom
Italia.

    In Italy, providers of network infrastructure and switched voice services as
well as national mobile operators must contribute to a universal service fund.
Such a requirement is to take effect in 1999 provided that Telecom Italia can
demonstrate on the basis of audited reports that its universal service
obligations impose on it net losses. Even in these circumstances, the Italian
regulator can exempt new entrants from an obligation to contribute to such a
universal service fund. Both the Italian competition agency and the European
Commission are likely to recommend such an exemption scheme to the Italian
regulator. However, Carrier1 cannot assess at this time any possible impact of
any such universal service obligations on its operating margins.

    THE NETHERLANDS.  The Netherlands liberalized voice telephony in July 1997.
Legislation to implement the requirements of the Full Competition Directive has
been enacted.

    Carrier1 has obtained the necessary authorization to provide in The
Netherlands the services included in its business plans. Though Carrier1 is
entitled under its authorization to acquire existing dark fiber transmission
capacity, it would be required to obtain additional authorization to obtain
rights of way and construct its own infrastructure. In addition, it may also be
required to obtain additional approvals in the event that it were to decide to
market services to end users directly connected to Carrier1's network rather
than provide services on a wholesale basis as currently anticipated. However,
Carrier1 does not expect that there would be any significant difficulty in
obtaining such approvals.

    Carrier1 has implemented an interconnection agreement with KPN Telecom and
it has obtained a switched access number from the Dutch regulator.

    SWITZERLAND. A new Telecommunications Act went into effect on January 1,
1998, together with ordinances containing more detailed regulations covering
telecommunications services, frequency management, numbering, terminal equipment
and license fees. The new Telecommunications Act provides for liberalization of
the Swiss telecommunication market as of January 1, 1998.

    Carrier1 has obtained the necessary authorization to provide services in
Switzerland. Although Switzerland is not a member of the European Union and
accordingly European Union directives do not apply, the Swiss regulatory agency,
Bakom, generally follows European Union policies and directives. Switzerland is
a party to the WTO Agreement as well, and Carrier1 expects that the national
regulatory body will follow the general principles and policies embedded in the
WTO Agreement.

    Carrier1 signed an interconnection agreement with Swisscom which has been
implemented, and it has obtained a switched access number.

    AUSTRIA. A new Telecommunications Act came into effect on January, 1, 1998,
together with ordinances providing more detailed regulations on
telecommunications services, interconnection and numbering. Carrier1 obtained
the necessary licenses in Austria.

    The interconnection rules provide for cost-based interconnection rates for
every licenseholder, without distinction between infrastructure owners and
resellers. Carrier1 signed an interconnection agreement with PTA (the Austrian
incumbent telephone operator) which has been implemented. It has also obtained a
switched access number from the Austrian regulator.

    SPAIN.  The Spanish government implemented the full liberalization of public
switched telephone services on December 1, 1998. Prior to full liberalization, a
second telecommunications operator was

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<PAGE>
authorized to compete with Telefonica de Espana, S.A., and a third national
voice telephony license was granted in May 1998. Cable television operators are
expected to apply for licenses to provide voice telephony services. In addition,
a third license for a mobile telecommunications operator was granted in June
1998. Carrier1 expects to be able to provide services on a wholesale basis to
these newly authorized operators.

    Carrier1 expects to file an application to provide infrastructure and
services in Spain in the first half of 1999. It will need a license and an
interconnection agreement by early 2000 when it plans to install a point of
presence in Spain.

    SWEDEN, DENMARK, FINLAND, NORWAY, AND IRELAND.  Carrier1 is or may be
planning to provide services in a number of countries including Sweden, Denmark,
Finland, Norway, and Ireland which have adopted a liberal approach to
authorizing new service providers.

    In Norway, new service providers must register with the national regulator,
and in Finland and Sweden, a similar notification procedure is required to
authorize new service providers. In Denmark, services and infrastructure can be
provided by new entrants on the basis of a class license requiring no
registration, notification, or prior approval procedures involving the national
regulator. Carrier1 has complied with the applicable procedures in each of these
countries.

    Carrier1 has entered into interconnection agreements with Tele Danmark in
Denmark and Telia in Sweden, but has not yet opened discussions with the main
national operators in Finland and Norway. In all of the above-mentioned
countries, it expects that interconnection arrangements will be implemented when
its points of presence become operational in these countries. Carrier1 has
obtained a switched access number in Finland, and it has applied for such
numbers in Sweden, Denmark and Norway.

    Any new service provider must obtain a license to provide services in
Ireland. Carrier1 has received such a license. Carrier1 expects that an
interconnection agreement with Telecom Eireann will be implemented when its
point of presence in Dublin is operational.

    OTHER COUNTRIES.  Carrier1 will also be able to provide service through
direct operating agreements with correspondent telecommunications operators in
countries where it has not been directly authorized to provide services. As a
consequence of its having obtained the status of a recognized operator agency
under the rules of the International Telecommunications Union, Carrier1 will
negotiate such correspondent agreements with foreign telecommunications
operators in circumstances where such agreements will result in lower
termination costs than might be possible through refile arrangements. See
"--Network--Existing and Planned Traffic Termination Agreements."

EMPLOYEES

    As of December 31, 1998, and March 31, 1999, Carrier1 employed 53 and 73
people, respectively. None of Carrier1's employees is represented by a labor
union or covered by a collective bargaining agreement. Carrier1 believes that
relations with its employees are good.

PROPERTIES

    Carrier1 leases certain office and other space under operating leases and
subleases that expire at various dates, including a lease of Carrier1
International GmbH's 762 square meter headquarters in Zurich, Switzerland, which
expires in 2003.

    Carrier1's aggregate rent expense was $1,097,000 for the period from
Inception to December 31, 1998.

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<PAGE>
LEGAL PROCEEDINGS

    Carrier1 may, from time to time, be a party to litigation that arises in the
normal course of its business operations. Carrier1 is not presently a party to
any such litigation that Carrier1 believes would reasonably be expected to have
a material adverse effect on its business or results of operations.

ENFORCEABILITY OF CERTAIN CIVIL LIABILITIES

    Carrier1 International is a societe anonyme organized under the laws of the
Grand Duchy of Luxembourg. Carrier1 International is a holding company that
conducts its operations primarily through other European companies. In addition,
certain members of Carrier1's board, all of its executive officers and certain
of the experts named herein are residents of countries other than the United
States. A substantial portion of Carrier1's assets and the assets of such
non-resident persons are located outside the United States. As a result, it may
not be possible for investors to:

    - effect service of process within the United States upon Carrier1 or such
      persons; or

    - enforce against Carrier1 or such persons in U.S. courts judgments obtained
      in such courts predicated upon civil liability provisions of the federal
      securities laws of the United States.

    There is doubt as to whether the courts of Luxembourg would recognize
jurisdiction of the U.S. courts in respect of judgments obtained in those courts
in actions against Carrier1 or such directors and officers, as well as certain
of the experts named herein, and as to whether Luxembourg courts would enforce
judgments of U.S. courts predicated upon the civil liability provisions of the
U.S. federal or state securities laws. There is also doubt as to whether
Luxembourg courts would admit original actions brought under the U.S. securities
laws. In addition, certain remedies available under the U.S. federal or state
laws may not be admitted or enforced by Luxembourg courts on the basis of being
contrary to Luxembourg's public policy. Carrier1 cannot assure investors that
they will be able to enforce any judgment against it, certain members of its
board, its executive officers or certain of the experts named herein, including
judgments under the U.S. securities laws.

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<PAGE>
                                   MANAGEMENT

DIRECTORS, EXECUTIVE OFFICERS AND OTHER KEY EMPLOYEES

    The following table sets forth certain information with respect to the
directors, executive officers and other key employees of Carrier1 as of December
31, 1998.

<TABLE>
<CAPTION>
NAME                                                       AGE                     POSITION WITH CARRIER1
- -----------------------------------------------------      ---      -----------------------------------------------------
<S>                                                    <C>          <C>
Stig Johansson.......................................          56   Chief Executive Officer, President of Carrier1 and
                                                                      Director of Carrier1 International
Eugene A. Rizzo......................................          47   Vice President, Sales and Marketing
Terje Nordahl........................................          51   Chief Operating Officer
Joachim W. Bauer.....................................          54   Chief Financial Officer
Kees van Ophem.......................................          36   Vice President, Purchase and General Counsel
Neil E. Craven.......................................          30   Vice President, Business Development
Phil Poulter.........................................          48   Managing Director of Sales, United Kingdom and
                                                                      Ireland
Edward A. Gross......................................          40   Managing Director of Sales, Germany, Austria and
                                                                      Switzerland
Isabelle Russier.....................................          34   Managing Director of Sales, France
Marcus J. Gauw.......................................          38   Managing Director of Sales, Internet
Gustav Schaefer......................................          43   Managing Director of Sales, Benelux
Carlos Colina........................................          46   Manager, Carrier Sales--North America
Rick Mikolajczuk.....................................          49   Project Director, Network Build
Glenn M. Creamer.....................................          36   Director of Carrier1 International
Jonathan E. Dick.....................................          40   Director of Carrier1 International
Mark A. Pelson.......................................          36   Director of Carrier1 International
Victor A. Pelson.....................................          61   Director of Carrier1 International
Thomas J. Wynne......................................          58   Director of Carrier1 International
</TABLE>

    STIG JOHANSSON has served as a director of Carrier1 International since
August 1998 and as Carrier1's Chief Executive Officer and President since March
1998 and has more than 30 years of experience in the telecommunications
industry. Prior to founding Carrier1, Mr. Johansson was President of Unisource
Carrier Services AG ("Unisource Carrier Services") from September 1996 until
February 1998, where he was responsible for transforming Unisource Carrier
Services from a network development and planning company into a fully
commercial, wholesale carrier of international traffic. Mr. Johansson was a
member of Unisource N.V.'s supervisory board from 1992 until 1996. Prior to
joining Unisource Carrier Services, Mr. Johansson worked for Telia AB ("Telia"),
the Swedish incumbent telephone operator, where he was most recently Executive
Vice President. During his 26 years at Telia, Mr. Johansson held a variety of
positions. He began in 1970 working in engineering operations and rose to head
of strategic network planning (1977), general manager of the Norrkoping Telecom
region (1978), head of CPE-business division (1980), executive vice president
and marketing director of Televerkit/Telia AB (1984) and Executive Vice
President responsible for Telia's start-up operations in the Nordic countries
and the United Kingdom (1995). He was a member of Telia's corporate management
board from 1985 to 1996. Mr. Johansson holds a Master's degree in Business
Economics from Hermods Institut, Sweden and a degree of Engineer of
Telecommunications from Lulea College, and he completed a senior executive
business course at IMD in Lausanne, Switzerland. He is a citizen of Sweden.

    EUGENE A. RIZZO has served as Carrier1's Vice President, Sales and Marketing
since March 1998 and has over 21 years of experience in international sales and
marketing and 10 years of experience in the telecommunications industry. From
1993 to 1998, Mr. Rizzo managed sales and marketing groups for several
affiliates of Unisource NV, including Unisource Carrier Services and
AT&T-Unisource

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<PAGE>
Communications Services ("AT&T-Unisource"), an international joint venture
between AT&T Corp. ("AT&T") and Unisource NV. Prior to joining Unisource, Mr.
Rizzo held various marketing and management positions with International
Business Machines Corporation ("IBM"), Wang Laboratories, Inc. and Tandem
Computers Inc. ("Tandem"). While at Tandem, Mr. Rizzo assisted in the start-up
of Tandem's European Telco Group. Mr. Rizzo holds a Master of Business
Administration degree from the University of Massachusetts. He is a citizen of
the United States.

    TERJE NORDAHL has served as Carrier1's Chief Operating Officer since March
1998 and has 25 years of experience in telecommunications operations. Mr.
Nordahl also has extensive experience in the computer and data industry. As a
Managing Director at Unisource Business Networks BV ("Unisource Business
Networks") from 1997 to 1998, he established and built the Unisource Business
Data Network in Norway. From 1995 to 1997, Mr. Nordahl was President of Telia AS
(Norway), Telia's subsidiary in Norway, where he supervised the building of an
ATM backbone network with integrated voice and data services. Mr. Nordahl worked
closely with Nortel on this project. From 1993 to 1995, Mr. Nordahl established
and operated Creative Technology Management AS ("CTM"), which provided business
development services for government and industrial organizations. Prior to
establishing CTM, Mr. Nordahl held engineering, development and marketing
positions with various companies, including IBM and telecommunications companies
affiliated with Ericsson (L.M.) Telephone Co. and ITT Corp. Mr. Nordahl holds a
Bachelor of Science degree from Heriot-Watt University, Edinburgh and has
completed the INSEAD Advanced Management Program. He is a citizen of Norway.

    JOACHIM W. BAUER has served as Carrier1's Chief Financial Officer since
March 1998 and has five years of experience in the telecommunications industry.
From 1994 to 1998, Mr. Bauer served as Chief Financial Officer of Unisource
Carrier Services. Before joining Unisource Carrier Services, Mr. Bauer held
various management positions with IBM and its affiliates, including Controller
of IBM (Switzerland). Mr. Bauer graduated from a commercial school in Zurich,
was educated at IMEDE business school, Lausanne, Switzerland, and completed the
senior executive program of the Swiss Executive School (SKU). Mr. Bauer holds a
Certified Diploma in Accounting and Finance (CPA). He is a citizen of Germany.

    KEES VAN OPHEM has served as Carrier1's Vice President, Purchase and General
Counsel since March 1998, with responsibility for interconnection, licensing and
legal affairs. Mr. van Ophem has seven years of experience in the
telecommunications industry. Prior to joining Carrier1, he was Vice President
Purchase and General Counsel for Unisource Carrier Services from 1994 to 1998
and was on its management board from its inception in early 1994. From 1992 to
1994 Mr. van Ophem served as legal counsel to Royal PTT Nederland NV (KPN)
("KPN"), with responsibility for the legal aspects of its start-up ventures in
Hungary, Bulgaria, Czech Republic and Ukraine and the formation of Unisource
Carrier Services. Prior to joining KPN, Mr. van Ophem worked at law firms in
Europe and the United States. Mr. van Ophem holds a Juris Doctorate degree from
the University of Amsterdam and, as a Fulbright scholar, a Master of Laws degree
in International Legal Studies from New York University. He is a citizen of The
Netherlands.

    NEIL E. CRAVEN has served as Carrier1's Vice President, Business Development
since March 1998 and has five years of experience in the telecommunications
industry. From 1995 to 1998, Mr. Craven was a member of the management team at
Unisource Carrier Services, initially responsible for Corporate Strategy and
Planning and later serving as Vice President of Business Development. Prior to
joining Unisource Carrier Services, Mr. Craven was employed by Siemens AG in
Germany, where he worked on various international infrastructure projects. Mr.
Craven has an Honors degree in Computer Engineering from Trinity College, Dublin
and a Master of Business Administration degree from the Rotterdam School of
Management. He is a citizen of Ireland.

    PHILIP POULTER has served as Carrier1's Managing Director of Sales, United
Kingdom and Ireland since June 1998 and has over 30 years of experience in the
telecommunications industry. Prior to joining Carrier1, Mr. Poulter was
Operations Director of ACC Long Distance UK Ltd. ("ACC"), a switch-based
provider of telecommunications services, from December 1997 to June 1998. From
March 1997 to

                                       77
<PAGE>
December 1997, Mr. Poulter served as Network & Carrier Services Director of ACC.
From August 1996 to March 1997, Mr. Poulter was Managing Director of Nelcraft
Services Ltd., a provider of installation and maintenance services relating to
the cable television and telecommunications industries. From March 1995 to
August 1996, Mr. Poulter served as Carrier Manager of ACC. From 1993 to 1995,
Mr. Poulter was employed as Sales Director for Business Communication for
Videotron Corporation Ltd. ("Videotron"), a U.K. provider of cable television
and telephony services. Prior to joining Videotron, Mr. Poulter held various
management, sales and engineering positions, including more than fifteen years
of experience in designing and implementing telecommunications switching and
transmission systems for British Telecom. Mr. Poulter is a director of Carrier1
UK Ltd., a subsidiary of Carrier1 International. Mr. Poulter has a Final
Certificate in Electronics and Communications from the London C & G Institute.
He is a citizen of the United Kingdom.

    EDWARD A. GROSS has served as Carrier1's Managing Director of Sales,
Germany, Austria and Switzerland since May 1998 and has over 20 years of
experience in the telecommunications and networking industries. Prior to joining
Carrier1, Mr. Gross served as Sales Director, Germany for Unisource Carrier
Services from December 1996 to May 1998. From March 1996 to December 1996, Mr.
Gross served as Director of Customer Services Engineering--Central Europe for
AT&T-Unisource. From 1992 to 1996, Mr. Gross was a member of the management team
at Unisource Business Networks, where he was responsible for the start-up of
operations in Germany and Austria and subsequently served as Director of
Customer Services. Prior to joining Unisource Business Networks, Mr. Gross was
employed by Unisys Corporation for more than 12 years, during which time he held
various positions in network support and software development, primarily in
Germany as well as South Korea and the United States. Mr. Gross holds a Bachelor
of Science degree in Management Studies from the University of Maryland and has
completed the Accelerated Development Program at London Business School. He is a
citizen of the United States.

    ISABELLE RUSSIER has served as Carrier1's Managing Director of Sales, France
since August 1998 and has three years of experience in the telecommunications
industry. From November 1997 to July 1998, Ms. Russier was employed in London by
ACC, where she handled various projects in its Business Development Europe
Division. From December 1995 to October 1997, Ms. Russier was employed in France
as General Manager of sales for UNIFI Communications, Inc., a U.S.-based
telecommunications value-added service provider. From 1992 to 1995, she worked
for Apple Computer, Inc., most recently as a Regional Sales Director, and from
1987 to 1992, she was employed by Intel Corp. in a variety of sales positions.
Ms. Russier holds an Engineering degree in Microelectronics and a European
Master of Business Administration degree (ISA) from the HEC School of
Management. She is a citizen of France.

    MARCUS J. GAUW has served as Carrier1's Managing Director of Sales, Internet
since May 1998 and has 13 years of experience in the telecommunications
industry. From 1996 to 1998, Mr. Gauw served as Sales Manager for Internet
Transit Services at AT&T-Unisource, and from 1994 to 1996, he served as Sales
Manager, Voice Services at AT&T-Unisource. From 1992 to 1994, Mr. Gauw was a
Senior Sales Consultant for Unisource Business Networks. Prior to joining
Unisource Business Networks, Mr. Gauw was employed by KPN for approximately
seven years, during which time he held various positions in sales and marketing.
Mr. Gauw holds a Bachelor's degree in Telecommunications and Electronics from
Hogere Technische School, Alkmaar, The Netherlands. He is a citizen of The
Netherlands.

    GUSTAV SCHAEFER has served as Carrier1's Managing Director of Sales, Benelux
since September 1998 and has over nine years of experience in the
telecommunications industry. From 1995 to 1998, Mr. Schaefer was employed by
Unisource Carrier Services, where he contributed to the development of the
service provider market. Prior to joining Unisource Carrier Services, Mr.
Schaefer was employed by KPN, where he served as a sales consultant and later
developed and implemented KPN's Call Center business solutions. Mr. Schaefer
received a Master's degree in Physics from Delft Technical University. He is a
citizen of The Netherlands.

                                       78
<PAGE>
    CARLOS COLINA has served as Carrier1's Manager, Carrier Sales--North America
since September 1998 and has over 23 years of experience in the
telecommunications industry. Prior to joining Carrier1, Mr. Colina handled
various sales and marketing assignments with AT&T, including responsibility for
directing AT&T's efforts in the assessment and analysis of the international
business switched services marketplace from 1993 to 1998. Mr. Colina has
extensive training in voice and data communications and holds a Bachelor's
degree in Information Sciences from Fordham University. He also has completed
the Wharton School of Business/AT&T business education program. He is a citizen
of the United States.

    RICK MIKOLAJCZUK has served as Project Director, Network Build for Carrier1
since November 1998 and has over 28 years of experience in the
telecommunications industry. Prior to joining Carrier1, Mr. Mikolajczuk was an
Engineering Manager for Telewest Communications PLC ("Telewest"), a provider of
cable television and telephony services to businesses and residences in the
United Kingdom, where he was responsible for engineering Telewest's National
Network from its design stage in early 1997 through to completion in October
1998. From 1971 to 1996, Mr. Mikolajczuk was employed by British Telecom, where
he gained extensive experience in duct, cable and transmission planning,
external operations and quality management. Mr. Mikolajczuk holds an Engineering
degree in Electronics from the University of Liverpool. He is a citizen of the
United Kingdom.

    GLENN M. CREAMER has served as a director of Carrier1 International since
August 1998. Mr. Creamer has been a Managing Director of Providence Equity
Partners Inc. since its inception in 1996 and is also a General Partner of
Providence Ventures L.P., which was formed in 1991. Mr. Creamer is also a Vice
President of Narragansett Capital Inc., which he joined in 1988. Mr. Creamer is
a director of American Cellular Corporation, Celpage, Inc., Epoch Networks, Inc.
and Wireless One Network L.P. Mr. Creamer received a Bachelor of Arts degree
from Brown University and a Master of Business Administration degree from the
Harvard Graduate School of Business Administration. He is a citizen of the
United States.

    JONATHAN E. DICK has served as a director of Carrier1 International since
August 1998. Mr. Dick has been a Managing Director of Primus Venture Partners,
Inc. since December 1993. Prior to joining Primus in June 1991, Mr. Dick held
various positions in sales management at Lotus Development Corporation. Mr. Dick
is also a director of PlanSoft Inc. Mr. Dick received a Bachelor of Science
degree in Applied Mathematics and Economics from Brown University and a Master
of Business Administration degree from the Harvard Graduate School of Business
Administration. He is a citizen of the United States.

    MARK A. PELSON has served as a director of Carrier1 International since
August 1998. Mr. Pelson is a Principal of Providence Equity Partners Inc., which
he joined in August 1996. Prior to 1996, Mr. Pelson was a co-founder and
director, from 1995 to 1996, of TeleCorp., Inc., a wireless telecommunications
company, and from 1989 to 1995 served in various management positions with AT&T,
including most recently as a general manager of strategic planning and mergers
and acquisitions. Mr. Pelson is a director of American Cellular Corporation,
Madison River Telephone Company, L.L.C. and Wired Ventures Inc. Mr. Pelson
received a Bachelor of Arts degree from Cornell University and a Juris Doctorate
from Boston University. Mr. Pelson is the son of Victor A. Pelson. He is a
citizen of the United States.

    VICTOR A. PELSON has served as a director of Carrier1 International since
January 1999. Mr. Pelson is a Senior Advisor to Warburg Dillon Read LLC., an
investment banking firm. He was a Director and Senior Advisor of Dillon, Read &
Co. Inc. at the time of its merger in 1997 with SBC Warburg. Before joining
Dillon, Read in April 1996, Mr. Pelson was associated with AT&T from 1959 to
March 1996, where he held a number of executive positions, including Group
Executive and President responsible for the Communications Services Group,
Executive Vice President and member of the Management Executive Committee. At
his retirement from AT&T, Mr. Pelson was Chairman of Global Operations (for what
is now AT&T, Lucent Technologies and NCR) and a member of the Board of
Directors. Mr. Pelson is also chairman of the board of trustees of New Jersey
Institute of Technology and a director of Eaton Corporation and United Parcel
Service of America, Inc. Mr. Pelson received a Bachelor of Science degree in
Mechanical Engineering from New Jersey Institute of Technology and a Master of
Business

                                       79
<PAGE>
Administration degree from New York University. Mr. Pelson is the father of Mark
A. Pelson. He is a citizen of the United States.

    THOMAS J. WYNNE has served as a director of Carrier1 International since
January 1999. Mr. Wynne is currently a partner with Sycamore Creek Development
Co. He was President and Chief Operating Officer of LCI International Inc. and
its subsidiaries from July 1991 to October 1997. From 1977 to 1991, Mr. Wynne
held several executive positions with MCI Communications Corp., including
President of the West Division, Vice President of Sales and Marketing for the
Mid-Atlantic Division, and Vice President in the Midwest Division. Mr. Wynne is
also a director of Advanced Radio Telecom Corp. Mr. Wynne holds a Bachelor of
Science degree in Political Science from St. Joseph's University. He is a
citizen of the United States.

BOARD OF DIRECTORS

    The general affairs and business of Carrier1 International are managed by
the Board of Directors (the "Board"). Carrier1 International's Articles of
Incorporation (the "Articles") provide for at least three directors appointed by
a general meeting of shareholders for terms no greater than six years. Under the
Articles, the number and terms of directors are to be determined, and each
director may be reelected or removed at any time, by a general meeting of
shareholders. Directors are not required to hold any shares in Carrier1
International by way of qualification. Carrier1 International is bound by the
joint signature of two directors or the sole signature of a managing director
for ordinary course management decisions, if one has been appointed by the
Board. Carrier1 International currently has six directors and has no persons
appointed as corporate officers.

COMMITTEES OF THE BOARD OF DIRECTORS

    Carrier1 International currently does not have any Board committees.

COMPENSATION OF DIRECTORS

    Carrier1 International will reimburse the members of the Board for their
reasonable out-of-pocket expenses incurred in connection with attending Board
meetings. Additionally Carrier1 International expects to maintain directors' and
officers' liability insurance. Members of the Board receive no other
compensation for services provided as a Director.

                                       80
<PAGE>
SUMMARY EXECUTIVE COMPENSATION TABLE


    The following table sets forth information concerning compensation for
services in all capacities awarded to, earned by or paid to, the Chief Executive
Officer and the other four most highly compensated executive officers of
Carrier1 during the period from March 4, 1998 through December 31, 1998. During
this period, these individuals held options in Carrier1 LLC, which in turn held
substantially all of the equity of Carrier1. Purchase of interests in the LLC by
employees of Carrier1 were contractually limited to the lower of (a) the amount
listed under the "Long Term Compensation" column or (b) the employee's portion
of a total of 11.1% of the outstanding LLC interests. Pursuant to a
restructuring of Carrier1's management equity, these options for LLC interests
have been cancelled and equivalent options for shares of Carrier1 International
common stock have been issued in their place. The economic terms of these new
options are substantially the same as the terms of the LLC options. The table
assumes that the maximum number of Class A Units would be purchased by such
purchasers.



<TABLE>
<CAPTION>
                                                                                      LONG TERM
                                                                                    COMPENSATION
                                                 SHORT TERM                     ---------------------
                                                COMPENSATION                      MAXIMUM NUMBER OF      ALL OTHER
                                           ----------------------                    SECURITIES        COMPENSATION
NAME AND PRINCIPAL POSITION                 PERIOD     SALARY(A)      BONUS      UNDERLYING OPTIONS       (A)(B)
- -----------------------------------------  ---------  -----------  -----------  ---------------------  -------------
<S>                                        <C>        <C>          <C>          <C>                    <C>
Stig Johansson...........................   March-
President and Chief Executive Officer      December
                                             1998      $ 245,569    $  46,044           711,111          $  61,738
Gene Rizzo...............................   March-
Vice President, Sales and Marketing        December
                                             1998        173,343       32,502           711,111             49,436
Terje Nordahl............................   April-
Chief Operating Officer                    December
                                             1998        135,207       25,352           355,555             44,217
                                            March-
Joachim W. Bauer.........................
Chief Financial Officer                    December
                                             1998        150,230       28,168           711,111             56,980
Kees van Ophem...........................   March-
Vice-President, Purchase and General
  Counsel                                  December
                                             1998        150,230       28,168           711,111             36,944
</TABLE>


- ------------------------


(a) Carrier1 records this compensation expense in Swiss Francs. The U.S. dollar
    amounts shown were calculated using an average exchange rate for the period
    of March 4, 1998 through December 31, 1998 of $0.69337 to SFr1.



(b) Consists of business expenses and contributions under a pension plan for its
    executive officers paid by Carrier1 International GmbH, a wholly owned
    subsidiary of Carrier1 International. Business expenses consist of car and
    travel expenses in the following amounts (in thousands):


<TABLE>
<S>                                                                    <C>
Stig Johansson.......................................................  $    22.2
Gene Rizzo...........................................................       22.2
Terje Nordahl........................................................       20.0
Joachim Bauer........................................................       22.2
Kees van Ophem.......................................................       22.2
</TABLE>

                                       81
<PAGE>
STOCK OPTION GRANTS AND FISCAL YEAR-END VALUES


    The following tables set forth information regarding grants of options to
purchase Class A Units in Carrier One, LLC (the "LLC") and the fiscal year-end
value of such options, which were granted to the executive officers listed in
the Summary Compensation Table above pursuant to the 1998 Option Plan. During
the period from March 4, 1998 through December 31, 1998, the LLC held
substantially all of the equity of Carrier1 International. Purchase of interests
in the LLC by employees of Carrier1 were contractually limited to the lower of
(a) the amount listed under the "Long Term Compensation" column in the Summary
Compensation Table above or (b) the employee's portion of a total of 11.1% of
the outstanding LLC interests. Pursuant to a restructuring of Carrier1's
management equity, these options for LLC interests have been cancelled and
equivalent options for shares of Carrier1 International common stock have been
issued in their place. The economic terms of these new options are substantially
the same as the terms of the LLC options.


                             OPTION GRANTS IN 1998


<TABLE>
<CAPTION>
                                                                 INDIVIDUAL GRANTS
                                              -------------------------------------------------------
                                                MAXIMUM    PERCENT OF
                                               NUMBER OF      TOTAL
                                              SECURITIES     OPTIONS
                                              UNDERLYING   GRANTED TO    EXERCISE                      PRESENT VALUE
                                                OPTIONS     EMPLOYEES      PRICE                        AT DATE OF
NAME                                            GRANTED      IN 1998     ($/SHARE)   EXPIRATION DATE     GRANT(A)
- --------------------------------------------  -----------  -----------  -----------  ----------------  -------------
<S>                                           <C>          <C>          <C>          <C>               <C>
Stig Johansson..............................     711,111         17.6%   $    1.00   March 4, 2008     $  106,666.65
Gene Rizzo..................................     711,111         17.6         1.00   March 4, 2008        106,666.65
Terje Nordahl...............................     355,555          8.8         1.00   March 4, 2008         53,333.25
Joachim W. Bauer............................     711,111         17.6         1.00   March 4, 2008        106,666.65
Kees van Ophem..............................     711,111         17.6         1.00   March 4, 2008        106,666.65
</TABLE>


- ------------------------


(a) The fair value of option grants is estimated on the date of grant using the
    minimum value option-pricing model, as allowed under SFAS 123 for nonpublic
    companies, for pro-forma footnote purposes with the following assumptions
    used: dividend yield of 0%, risk-free interest rate of 5.53%, and expected
    option life of 5 years.


    AGGREGATED OPTION/SAR EXERCISES IN LAST FISCAL YEAR AND FISCAL YEAR-END
                               OPTION/SAR VALUES

<TABLE>
<CAPTION>
                                                                                          NUMBER OF
                                                                                         SECURITIES            VALUE OF
                                                                                         UNDERLYING          UNEXERCISED
                                                                                         UNEXERCISED         IN-THE-MONEY
                                                                                       OPTIONS/SARS AT     OPTIONS/SARS AT
                                                                                      DECEMBER 31, 1998  DECEMBER 31, 1998(A)
                                                  LLC UNITS                           -----------------  --------------------
                                                  ACQUIRED                              EXERCISABLE/         EXERCISABLE/
NAME                                             ON EXERCISE       VALUE REALIZED       UNEXERCISABLE       UNEXERCISABLE
- --------------------------------------------  -----------------  -------------------  -----------------  --------------------
<S>                                           <C>                <C>                  <C>                <C>
Stig Johansson..............................              0           $       0            --/711,111       $        --/--
Gene Rizzo..................................              0                   0            --/711,111                --/--
Terge Nordahl...............................              0                   0            --/355,555                --/--
Joachim W. Bauer............................              0                   0            --/711,111                --/--
Kees van Ophem..............................              0                   0            --/711,111                --/--
</TABLE>

- ------------------------

(a) No options were in-the-money on December 31, 1998.

    Under the 1998 Option Plan, the LLC authorized the issuance of options for
up to 4,444,444 Class A Units, of which options for 4,044,442 underlying Class A
Units were granted. These options have been cancelled in exchange for the grant
of new options to acquire shares of Carrier1 International's common

                                       82
<PAGE>
stock. See "Certain Relationships and Related Transactions--Equity Investor
Agreements--Securities Purchase and Cancellation Agreement."


    Carrier1 authorized the issuance of options for up to 2,222,222 shares of
Carrier1 International's common stock pursuant to its 1999 Share Option Plan
dated as of December 30, 1998, of which Carrier1 has granted 2,110,968 options
to its employees and anticipates granting further options to its employees in
the near term, including through an increase in the shares authorized under the
1999 Share Option Plan. Carrier1 has also issued options to acquire 20,000
shares to each of Messrs. Wynne and Pelson outside the scope of the 1999 Option
Plan. See "Certain Relationships and Related Transactions--Equity Investor
Agreements--1999 Share Option Plan."


EMPLOYMENT AGREEMENTS

    Each of Stig Johansson, Eugene A. Rizzo, Terje Nordahl, Joachim Bauer and
Kees van Ophem (the "Executives") has entered into an employment agreement with
a wholly owned subsidiary of Carrier1 International. Such agreements include,
among others, the following terms:

    TERM.  The employment agreements may be terminated by either party after
August 31, 1999, upon six months' notice.

    NONDISCLOSURE, NONCOMPETITION AND NONSOLICITATION COVENANTS.  Each Executive
has agreed that during his period of employment and the eighteen months
thereafter (the "Non-Compete Period") he or she will refrain from disclosing
confidential information and will not participate in any business that is
engaged in the provision of international long distance telecommunications
services or that is otherwise in competition with any business conducted by the
LLC or its subsidiaries. Additionally, each Executive has agreed that during the
Non-Compete Period, he or she will not induce or attempt to induce any employee
of Carrier1 to leave the employ of Carrier1, nor will he attempt to induce any
supplier, distributor or customer of Carrier1 or its affiliates to cease doing
business with Carrier1. In addition, each Executive is subject to nondisclosure,
noncompetition and nonsolicitation covenants pursuant to Deeds of Covenant
entered into among the LLC, Carrier One Limited, Providence and the Executives.

COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION

    Carrier1 International currently does not have a compensation committee and
the compensation of executive officers and other key employees of Carrier1 are
determined by the Board. Stig Johansson, Carrier1's President and Chief
Executive Officer, is currently a member of the Board and participates in such
determination.

                                       83
<PAGE>
                 CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

EQUITY INVESTMENTS


    As of May 1, 1999, shares of Carrier1 International's common stock have been
subscribed and paid for by Carrier1's management and employees, Providence
Equity Partners L.P. (which holds one share) and the LLC. Messrs. Johansson,
Bauer, Rizzo, van Ophem, Craven, Nordahl, Gross and Poulter are among the
management that have subscribed and paid for outstanding shares.


    The LLC is the vehicle through which Providence and Primus participate in
the equity investment in Carrier1 International. In addition, Thomas J. Wynne
and Victor A. Pelson, who are directors of Carrier1 International, hold
interests in the LLC through arrangements arrived at separately with Providence
and Primus. Messrs. Wynne and Pelson each own (directly or through trusts
organized for the benefit of family members) 400,000 Class A Units in the LLC,
acquired at a purchase price of $1.00 per Class A Unit. Messrs. Wynne and Pelson
each disclaims beneficial ownership of any Class A Units in any such trusts. Mr.
Wynne's and Mr. Pelson's Class A Units relate to a total of 400,000 shares of
Carrier1 International's common stock to be held by the LLC or approximately
1.13% of Carrier1 International's common stock on a fully diluted basis. Messrs.
Wynne and Pelson, however, do not directly hold any outstanding shares of
Carrier1 International's common stock.


    As of May 1, Carrier1 had substantially completed a restructuring of its
management equity arrangements. Pursuant to this restructuring, each of Messrs.
Johansson, Bauer, Rizzo, van Ophem, Craven, Nordahl, Gross and Poulter in effect
has exchanged his equity interests and options that he had held in the LLC to
acquire an equivalent dollar amount of shares and options of Carrier1
International common stock. Each effected this exchange through a series of
transactions with the LLC, Providence and Primus and Carrier1 International.
These individuals' portions of the total equity investment in Carrier1
International did not change significantly as a result of this restructuring,
but each of these individuals will hold common stock and options to acquire
common stock of Carrier1 International directly. In addition, Carrier1
International has granted Thomas J. Wynne and Victor A. Pelson options to
purchase a total of 40,000 shares of Carrier1 International's common stock
(20,000 shares of common stock for each), at $2.00 per share.


    1999 SHARE OPTION PLAN


    The Board of Carrier1 International has adopted the 1999 Share Option Plan,
dated as of December 30, 1998 (the "1999 Share Option Plan"), under which the
Company and related companies of the consolidated Carrier1 group may grant to
any employee or director options (the "Options") for shares of Carrier1
International's common stock ("Shares") or other equity securities issued by
Carrier1 International. The Option Plan is administered by the Board or a
committee appointed by the Board, and authorizes the Board or such committee to
issue Options in such forms and on such terms as determined by the Board or such
committee. The Board or such committee may determine the number of Options to
grant, provided that the number of Shares issued pursuant to the Option Plan
shall be no greater than 2,222,222 Shares. The per Share exercise price for the
Options may not be less than $2.00. If Options are to be granted to an employee
of a subsidiary, such subsidiary will grant such Options instead of Carrier1
International. Carrier1 International will grant the subsidiary options to
acquire Shares to meet its Option obligations at a per Share exercise price
based upon an agreed fair market value (or, failing agreement, a fair market
value determined by the Board). Options granted under the Option Plan will vest
in five equal annual installments beginning the first anniversary of the grant
of such Options. Options will expire if not exercised within 10 years of the
grant, or on an earlier date as specified by the Board or the committee. If the
employment of a participant is terminated for any reason, all unvested Options
will immediately expire and vested Options must be exercised within a particular
number of days, which number will vary depending on the reasons for termination.
Subject to certain exceptions, Options will be nontransferable during the life
of an optionee except pursuant to a valid domestic relations order. Upon an
optionee's


                                       84
<PAGE>
death, disability or termination of employment, the subsidiary which employs the
optionee, or its designee, will have the right to repurchase all Shares held by
the optionee, whether or not such Shares were acquired pursuant to the exercise
of Options. Under Luxembourg law, Carrier1 International and certain
subsidiaries may be precluded from exercising such right directly.

    Carrier1 has granted Options pursuant to the 1999 Share Option Plan to
acquire approximately 2,110,968 Shares at an exercise price of $2.00 per Share
plus applicable capital duty (currently 1% of the subscription price payable to
Carrier1 International by the subsidiary granting the applicable Option).
Carrier1 intends to grant additional Options in the future.

    SECURITIES PURCHASE AGREEMENT


    Carrier1 International, the LLC and up to 44 employee investors
(collectively, the "Management Investors") have entered into the Securities
Purchase Agreement (the "Securities Purchase Agreement") (effective as of March
1, 1999) under which each Management Investor has purchased a specified number
of Shares at $2.00 per Share, for an aggregate purchase price of $2.14 million.
As part of the restructuring of the management equity arrangements described
above, each of Messrs. Johansson, Bauer, Rizzo, van Ophem, Craven, Nordahl,
Gross, and Poulter has, in effect, exchanged 68,260 Class A Units (at $1.00 per
unit) to acquire, pursuant to the Securities Purchase Agreement, 34,130 Shares
(at $2.00 per Share). Carrier1 International intends in the future to issue
additional Shares to employees that are or become party to the Securities
Purchase Agreement. The Securities Purchase Agreement also contains provisions
relating to the sale of a number of Shares (at $2.00 per Share) sufficient to
complete the equity investment in Carrier1 International by the LLC in which
Providence, Primus and Messrs. Wynne and Pelson have membership interests. The
$60.0 million Equity Investment by Providence and Primus was completed in
February, 1999. The LLC has paid in an additional $800,000 to the capital of
Carrier1 International. Issuance of the remaining 400,000 Shares to the LLC
pursuant to these provisions is pending as of May 1, 1999. The Securities
Purchase Agreement provides that Carrier1 International will indemnify the LLC
and Management Investors for, among other things, losses related to any
transaction financed or to be financed with proceeds from the sale of securities
purchased pursuant to the Securities Purchase Agreement or any related agreement
and environmental losses. The Securities Purchase Agreement contains customary
conditions, representations and warranties.


    REGISTRATION RIGHTS AGREEMENT

    Carrier1 International, the LLC, and Messrs. Johansson, Bauer, Rizzo, van
Ophem, Craven, Nordahl, Gross, Poulter, Wynne and Pelson (the "Original
Management Investors") have entered into a registration rights agreement
(effective as of March 1, 1999) (the "Registration Rights Agreement"). The
Registration Rights Agreement provides that the LLC may at any time request
registration under the Securities Act of its Shares and certain other equity
securities. In addition, the Registration Rights Agreement gives certain
piggyback registration rights to the LLC and the Original Management Investors
and, at the request of certain Original Management Investors, possibly
additional employees party to the Securities Purchase Agreement or the
Securityholders' Agreement described below. The Original Management Investors do
not, however, have piggyback rights in connection with an initial public
offering. The Registration Rights Agreement contains provisions governing the
registration statement filing process. Among other things, it provides that
Carrier1 International will bear all registration expenses and expenses for each
piggyback registration in which the LLC or any of the Original Management
Investors participate, other than underwriting discounts and commissions, in
connection with its obligations under the Registration Rights Agreement.

    SECURITYHOLDERS' AGREEMENT

    In connection with the Securities Purchase Agreement, Carrier1 International
has entered into a securityholders' agreement (effective as of March 1, 1999)
(the "Securityholders' Agreement") with

                                       85
<PAGE>
Messrs. Wynne and Pelson, the Management Investors and the LLC. The
Securityholders' Agreement places restrictions on Management Investors' ability
to transfer their securities without the prior written consent of the Board
except under special circumstances. Transfers of securities are subject to the
right of first refusal by the LLC or its transferee. The LLC will also benefit
from preemptive rights in certain other circumstances. The Securityholders'
Agreement also provides that the Management Investors will (i) consent to and
raise no objections to a sale of Carrier1 International approved by the Board
and (ii) comply with a Board request to pledge their securities to secure
financing to be provided to Carrier1 International. Management Investors have
tag-along rights in the event of sales by the LLC or its members of securities
if a change of control is involved. The Securityholders' Agreement provides for
certain individuals to be appointed to the Board. Finally, under the
Securityholders' Agreement, the Management Investors agree not to disclose
confidential information of, compete with, or solicit employees or customers
from the LLC or the Company.

EPOCH PEERING ARRANGEMENT


    Carrier1 has entered into a peering arrangement with Epoch Networks. The
contract with Epoch Networks provides for the free exchange of data traffic
between Carrier1 and Epoch Networks. A fund managed by Providence that holds a
majority of the Class A Units of the LLC and another fund managed by Providence
that also holds an interest in Class A Units of the LLC own a combined 21% of
the outstanding equity of Epoch Networks.


OTHER TRANSACTIONS

    The LLC has advanced a loan of $68,260, bearing interest at 12%, to Mr. van
Ophem, evidenced by a promissory note dated June 30, 1998, to finance his equity
investment in the LLC. As of December 31, 1998, Mr. van Ophem owed $68,260 to
the LLC. Mr. van Ophem is required to repay principal and interest on the loan
in five equal annual installments of $18,936 commencing July 1, 2001. Carrier1
expects (effective as of March 1, 1999) to become the creditor with respect to
such loan.

    During the period ended December 31, 1998, Carrier1 reimbursed Providence
and Primus for expenses incurred in connection with the formation of Carrier1
and the negotiation of certain agreements entered into by Carrier1. Such
reimbursements totaled $339,000 and were expensed as selling, general and
administrative expenses.

                                       86
<PAGE>
                           PRINCIPAL SECURITY HOLDERS

    The following table sets forth certain information regarding the beneficial
ownership of the Shares of Carrier1 International, as of May 12, 1999, by

        (1) each person known to Carrier1 International to own beneficially more
    than 5% of Carrier1 International's outstanding Shares,

        (2) each director of Carrier1 International,

        (3) each executive officer of Carrier1 International listed in the
    Summary Compensation Table under "Management" above and

        (4) all executive officers and directors of Carrier1 International as a
    group.

All information with respect to beneficial ownership has been furnished to
Carrier1 International by the respective shareholders of Carrier1 International.

<TABLE>
<CAPTION>
                                                                                                      PERCENTAGE OF
NAME AND ADDRESS OF BENEFICIAL OWNER(1)                                            NUMBER OF SHARES      SHARES
- ---------------------------------------------------------------------------------  -----------------  -------------
<S>                                                                                <C>                <C>
Carrier One, LLC.................................................................       30,399,999          90.52%
  c/o Providence Equity Partners Inc.
  901 Fleet Center
  50 Kennedy Plaza
  Providence, RI 02903
Providence Equity Partners L.P.(2)...............................................       30,400,000          90.52
  901 Fleet Center
  50 Kennedy Plaza
  Providence, RI 02903
Jonathan M. Nelson(2)............................................................       30,400,000          90.52
Paul J. Salem(2).................................................................       30,400,000          90.52

<CAPTION>

NAME OF EXECUTIVE OFFICER OR DIRECTOR
- ---------------------------------------------------------------------------------
<S>                                                                                <C>                <C>
Stig Johansson(3)................................................................          105,241              *
Eugene A. Rizzo(3)...............................................................          105,241              *
Terje Nordahl(3).................................................................           69,685              *
Joachim Bauer(3).................................................................          105,241              *
Kees van Ophem(3)................................................................          105,241              *
Glenn M. Creamer (2).............................................................       30,400,000          90.52
Jonathan E. Dick.................................................................               --             --
Mark A. Pelson...................................................................               --             --
Victor A. Pelson(4)..............................................................           20,000              *
Thomas J. Wynne(4)...............................................................           20,000              *
All directors and executive officers as a group (11 persons).....................       31,035,890          92.41
</TABLE>


- ------------------------

*   Less than one percent.

(1) In accordance with Rule 13d-3 under the Securities Exchange Act of 1934, as
    amended (the "Exchange Act"), a person is deemed a "beneficial owner" of a
    security if he or she has or shares the power to vote or direct the voting
    of such security or the power to dispose or direct the disposition of such
    security. A person is also deemed to be a beneficial owner of any securities
    which that person has the right to acquire beneficial ownership of within 60
    days. More than one person may be deemed to be a beneficial owner of the
    same securities.

(2) The LLC is the direct beneficial owner of 29,999,999 Shares and Providence
    Equity Partners L.P. ("Providence L.P.") is the direct beneficial owner of 1
    Share. Providence L.P. is the majority Class A Unit holder of the LLC, and
    by virtue of such status may be deemed to be the beneficial owner of the
    Shares in which the LLC has direct beneficial ownership. Providence Equity
    Partners L.L.C. ("PEP LLC") is the general partner of Providence L.P., and
    by virtue of such status may be deemed to be the

                                       87
<PAGE>
    beneficial owner of the Shares in which Providence L.P. has direct or
    indirect beneficial ownership. Jonathan M. Nelson, Glenn M. Creamer and Paul
    J. Salem may be deemed to share voting and investment power with respect to
    the Shares in which PEP LLC has direct or indirect beneficial ownership.
    Each of Jonathan M. Nelson, Glenn M. Creamer, Paul J. Salem, PEP LLC and
    Providence L.P. disclaims such deemed beneficial ownership.


(3) Includes 34,130 Shares and an additional 71,111 Shares (35,555, in the case
    of Mr. Nordahl) issuable to each such person upon exercise of options which
    are exercisable within 60 days.


(4) Consists of options that Carrier1 International has issued to each of Thomas
    J. Wynne and Victor A. Pelson for a total of 40,000 Shares of its common
    stock (20,000 Shares each).

    The following table sets forth certain information regarding the current
beneficial ownership of Class A Units (the "Class A Units") of the LLC by:

    (1) Each director of Carrier1 International,

    (2) Each executive officer of Carrier1 International listed in the Summary
Compensation Table under "Management" above.

    (3) All directors and executive officers of Carrier1 International as a
group as of May 1, 1999.

<TABLE>
<CAPTION>
                                                                                                      PERCENTAGE OF
NAME OF DIRECTOR/EXECUTIVE OFFICER(1)                                               NUMBER OF UNITS     UNITS(1)
- ----------------------------------------------------------------------------------  ---------------  ---------------
<S>                                                                                 <C>              <C>
Stig Johansson....................................................................        --               --
Eugene A. Rizzo...................................................................        --               --
Terje Nordahl.....................................................................        --               --
Joachim Bauer.....................................................................        --               --
Kees van Ophem....................................................................        --               --
Glenn M. Creamer (2)..............................................................      50,000,000          82.24%
Jonathan E. Dick..................................................................        --               --
Mark A. Pelson....................................................................        --               --
Victor A. Pelson (3)..............................................................         400,000          *
Thomas J. Wynne (3)...............................................................         400,000          *
All directors and executive officers as a group (11 persons)......................      50,800,000          83.55%
</TABLE>

- ------------------------
*   Less than one percent.

(1) Based upon 60.8 million Class A Units outstanding.

(2) Providence L.P. holds 50,000,000 Class A Units. PEP LLC is the general
    partner of Providence L.P., and by virtue of such status may be deemed to be
    the beneficial owner of the Class A Units in which Providence L.P. has
    direct or indirect beneficial ownership. Glenn M. Creamer may be deemed to
    share voting and investment power with respect to the Class A Units in which
    PEP LLC has direct or indirect beneficial ownership. Each of Glenn M.
    Creamer and PEP LLC disclaims such deemed beneficial ownership.

(3) Thomas J. Wynne and Victor A. Pelson each have purchased (directly or
    through trusts organized for the benefit of family members) 400,000 Class A
    Units in the LLC, which in turn will use the proceeds of such purchases to
    acquire a total of 400,000 Shares. These Class A Units do not include
    additional options that Carrier1 International has issued to each of Thomas
    J. Wynne and Victor A. Pelson for a total of 40,000 Shares of its common
    stock (20,000 Shares each). Messrs. Wynne and Pelson intend to disclaim
    beneficial ownership in any Class A Units held in any such trusts.

                                       88
<PAGE>
                            DESCRIPTION OF THE NOTES


    The old dollar notes and the old Euro notes were issued under separate
indentures, each dated as of February 19, 1999. The Chase Manhattan Bank is the
trustee under each indenture. The new dollar notes will be issued under the
dollar indenture and the new Euro notes will be issued under the Euro indenture.
The indentures have been filed as exhibits to the registration statement of
which this prospectus is a part. They are available as set forth under the
heading "Where You Can Find More Information." The terms of the new notes of a
series are identical to the terms of the old notes of such series, except that
the new notes will be registered under the Securities Act and will not contain
restrictions on transfer or include provisions relating to additional interest
and will contain different administrative terms. New notes will otherwise be
treated as notes for purposes of the indentures.



    The following is a summary of the material provisions of the indentures.
This summary does not purport to be complete. It is subject to, and is qualified
in its entirety by reference to, all the provisions of the indentures, including
terms defined in the indentures and provisions of the Trust Indenture Act of
1939. Whenever particular defined terms of the indentures not otherwise defined
here are referred to, such defined terms are incorporated here by reference. For
definitions of certain capitalized terms used in the following summary, see
"--Certain Definitions." In this summary, "Carrier1 International" refers only
to Carrier1 International S.A. and its successors under the relevant indenture
and not to any of Carrier1 International S.A.'s subsidiaries.



    BRIEF DESCRIPTION OF THE NOTES



    The notes are:



    - general, unsubordinated obligations of Carrier1 International;



    - unsecured, except as indicated under "--Security" below; and



    - issued only in fully registered form, without coupons.



    The dollar notes will be represented by one or more permanent global dollar
notes. These global dollar notes will be registered in the name of The
Depository Trust Company, commonly known as "DTC". The relevant trustee will
hold these global dollar notes as custodian for DTC.



    Old Euro notes offered and sold in transactions outside the United States in
reliance on Regulation S are represented solely by certificated Euro notes.
Other Euro notes will be represented by one or more permanent global Euro notes.
Global Euro notes will be deposited with the relevant trustee, as common
depositary for Euroclear and Cedel Bank. If a qualified institutional buyer of a
beneficial interest in a global Euro note wishes to hold that interest through
DTC, those beneficial interests will be represented by one or more permanent
global Euro notes. These DTC Euro notes will be registered in the name of DTC.
The relevant trustee will hold these DTC Euro notes as custodian for DTC.



    Carrier1 International will not impose any service charge for any
registration of transfer or exchange of notes. However, Carrier1 International
may require payment of a sum sufficient to cover any transfer tax or other
similar governmental charge payable in connection with a transfer or exchange.



    PRINCIPAL, MATURITY AND INTEREST



    Carrier1 International will issue new dollar notes with a maximum aggregate
principal amount of $160.0 million and new Euro notes with a maximum aggregate
principal amount of [Euro]85.0 million. Carrier1 International will issue dollar
notes in denominations of $1,000 and integral multiples of $1,000. Carrier1
International will issue Euro notes in denominations of [Euro]1,000 and integral
multiples of [Euro]1,000. The notes will mature on February 15, 2009.


                                       89
<PAGE>

    Interest on the notes will accrue at a rate of 13.25% per annum and will be
payable semi-annually in arrears on February 15 and August 15 of each year,
commencing on August 15, 1999. Carrier1 International will make each interest
payment to the holders of record of the notes on the immediately preceding
February 1 and August 1.



    Interest on the notes will accrue from the date of original issuance or, if
interest has already been paid, from the date it was most recently paid.
Interest will be computed on the basis of a 360-day year comprised of twelve
30-day months.



    All payments on the notes will be made at the office or agency of Carrier1
International in the Borough of Manhattan, the City of New York. Transfers or
exchanges of the notes may also be made at this office or agency. This office or
agency will initially be the corporate trust office of the relevant trustee in
the City of New York. Carrier1 International may pay interest by check mailed to
the holders of the notes at their addresses as they appear in a register kept
pursuant to the relevant indenture.



    The Company may issue additional notes ("Additional Notes") under the
indentures. Old notes, new notes and any Additional Notes will be treated as a
single class for all purposes under the relevant indenture. References in this
"Description of the Notes" to the notes refer to the relevant series of notes.


    THE GLOBAL SECURITIES


    Ownership of beneficial interests in a global note will be limited to
persons, known as "participants," who have an account with DTC or Euroclear and
Cedel Bank or persons who hold interests through participants. Qualified
institutional buyers may hold their interest in a global note directly through
DTC or Euroclear and Cedel Bank, if they are participants in such system, or
indirectly through organizations which are participants in such system.
Beneficial interests in the global dollar notes and DTC Euro notes will be shown
on records maintained by DTC or its participants. Transfers of these beneficial
interests will be effected only through records maintained by DTC or its
participants. Beneficial interests in the global Euro notes will be shown on
records maintained by Euroclear and Cedel Bank or their participants. Transfers
of these beneficial interests will be effected only through records maintained
by Euroclear, Cedel Bank or their participants. Carrier1 expects that, upon
deposit of a global note representing new notes, DTC or Euroclear or Cedel Bank
will credit the account of participants tendering old notes in exchange for new
notes with an interest in the applicable global note. All beneficial interests
in the global securities will be subject to the procedures and requirements of
DTC, Euroclear or Cedel Bank. Transactions settled through DTC, Euroclear and
Cedel will settle on a T+3 basis.



    Owners of beneficial interests in the global securities will not be entitled
to have notes registered in their names. They also will not have physical
delivery of definitive certificates representing individual notes except in
limited circumstances. The laws of some jurisdictions may require some
purchasers to take physical delivery of the notes. Accordingly, the ability to
transfer interests in notes represented by a global note to such persons may be
limited. In addition, DTC, Euroclear and Cedel Bank can act only on behalf of
their respective participants, who in turn act on behalf of persons who hold
interests through such participants. Therefore, the lack of a physical
definitive note may affect the ability of a person having an interest in a
global note to pledge or transfer that interest to persons or entities that do
not participate in DTC's, Euroclear's or Cedel Bank's system, or to take other
actions.



    So long as DTC, Euroclear or Cedel Bank is the registered owner or holder of
any of the global securities, the relevant organization (or its nominee) will be
considered the sole owner or holder of the notes represented by such global
notes for all purposes under the indentures. No beneficial owner of an interest
in the global notes will be able to transfer that interest except in accordance
with DTC's, Euroclear's or Cedel Bank's applicable procedures, in addition to
those provided for under the relevant indenture.


                                       90
<PAGE>

    Transfers between participants in DTC will be effected in accordance with
DTC's procedures. Those transfers will be settled in same-day funds. Transfers
between participants in Euroclear or Cedel Bank will be effected in the ordinary
way in accordance with their respective rules and operating procedures.



    Carrier1 International expects that DTC, Euroclear or Cedel Bank will take
any action permitted to be taken by a holder of notes only at the direction of
their participants and only for the portion of the notes as to which such
participants have given direction.


    PAYMENTS


    Payments will be made through a paying agent to :



    - DTC for global dollar notes and DTC Euro notes or



    - Euroclear or Cedel Bank for global Euro notes other than the DTC Euro
      notes.



All amounts payable under the dollar notes will be payable in U.S. dollars and
all amounts payable under the Euro notes will be payable in Euro, except as
otherwise provided below. Carrier1 International, the trustees, the transfer
agent and the paying agent will not be liable or responsible for:



    - keeping or reviewing any records relating to beneficial ownership
      interests in the global notes or



    - payments for beneficial ownership interests in the global notes.



If the Euro notes are included in the regulated unofficial market (Freiverkehr)
of the Frankfurt Stock Exchange, Carrier1 International will maintain a paying
agent and registrar in Germany.



    Carrier1 International expects that DTC, Euroclear or Cedel Bank, upon
receipt of any payments on the global notes, will credit participants' accounts
with payments in proportion to their beneficial interests, as shown on the
records of the applicable organization. Carrier1 International also expects that
payments by participants to owners of beneficial interests in the global notes
will be governed by standing instructions and customary practice. Such payments
will be the responsibility of such participants.



    PAYMENTS ON GLOBAL EURO NOTES.  Payments to holders of global Euro notes in
respect of principal and interest on the Euro notes will be made in Euro, except
as may otherwise be agreed between any applicable securities clearing system and
any holders. See "--Currency Conversions for Holders of Beneficial Interests in
DTC Euro Notes." Payments will be subject in all cases to any applicable fiscal
or other laws and regulations. None of Carrier1 International, the trustees or
any paying agent shall be liable to any person for any commissions, costs,
losses or expenses relating to any currency conversion or rounding.



    CURRENCY CONVERSIONS FOR HOLDERS OF BENEFICIAL INTERESTS IN DTC EURO
NOTES.  Investors who hold beneficial interests in DTC Euro notes, directly or
indirectly, through DTC will be paid in U.S. dollars converted from payments in
Euro by the applicable agent unless the registered holder, on behalf of an owner
of beneficial interests, elects to receive payments in Euro or the chosen
currency, as the case may be. All costs of conversion, if any, will be borne by
holders of beneficial interests in the DTC Euro notes, by deduction from such
payments.



    An owner of a beneficial interest in a DTC Euro note may receive payment in
Euro by notifying the DTC participant through which it holds its interest on or
prior to the record date of (a) the owner's election to receive payment in Euro
and (b) wire transfer instructions to an account entitled to receive the
relevant payment. The DTC participant must notify DTC of the owner's election
and wire transfer instructions (a) on or prior to the second New York business
day after the record date for any payment of interest and (b) on or prior to the
eighth day prior to the payment of principal. DTC will notify the paying agent
of such election and wire transfer instructions (a) on or prior to the fourth
New York business day after the record date for any payment of interest and (b)
on or prior to the sixth New York business day prior to the payment of
principal. If the DTC participant, DTC and the paying agent receive complete


                                       91
<PAGE>

instructions on or prior to such dates, such owner will receive payment in Euro
outside DTC. Otherwise the paying agent will only make U.S. dollar payments to
such owner. All costs of payment by wire transfer will be borne by registered
holders receiving such payments by deduction from such payments. For purposes of
the foregoing, "New York business day" means a day all banking institutions are
not authorized or obligated by law or executive order to be closed in The City
of New York.


    Investors may be subject to foreign exchange risks that may have important
economic and tax consequences to them.

    INFORMATION CONCERNING DTC, EUROCLEAR AND CEDEL


    Carrier1 International understands that: DTC is a limited purpose trust
company organized under the laws of the State of New York, a "banking
organization" within the meaning of New York Banking Law, a member of the
Federal Reserve System, a "clearing corporation" within the meaning of the
Uniform Commercial Code and a "Clearing Agency" registered pursuant to the
provisions of Section 17A of the Exchange Act. DTC was created to hold
securities for its participants and facilitate the clearance and settlement of
securities transactions between participants through electronic book-entry
changes in accounts of its participants, thereby eliminating the need for
physical movement of certificates. Participants include securities brokers and
dealers, banks, trust companies and clearing corporations and certain other
organizations. Indirect access to the DTC system is available to others, such as
banks, brokers, dealers and trust companies that clear through or maintain a
custodial relationship with a participant, either directly or indirectly
("indirect participants").



    Carrier1 International understands that: Euroclear and Cedel Bank hold
securities for participating organizations and facilitate the clearance and
settlement of securities transactions between their respective participants
through electronic book-entry changes in accounts of such participants.
Euroclear and Cedel Bank provide to their participants, among other things,
services for safekeeping, administration, clearance and settlement of
internationally traded securities and securities lending and borrowing.
Euroclear and Cedel Bank interface with domestic securities markets. Euroclear
and Cedel Bank participants are financial institutions such as underwriters,
securities brokers and dealers, banks, trust companies and certain other
organizations. Indirect access to Euroclear or Cedel Bank is also available to
others such as banks, brokers, dealers and trust companies that clear through or
maintain a custodian relationship with a Euroclear or Cedel Bank participant,
either directly or indirectly.



    Subject to compliance with any transfer restrictions applicable to the
global notes, transfers between the DTC participants, on the one hand, and
Euroclear or Cedel Bank participants, on the other hand, will be effected
through DTC in accordance with DTC's rules. These transfers will require
delivery of instructions to Euroclear or Cedel Bank in accordance with their
rules and procedures and within their established deadlines. Euroclear or Cedel
Bank will, if the transaction meets its settlement requirements, deliver
instructions to its depositary to take action to effect final settlement on its
behalf by delivering or receiving interests in the global notes in DTC, and
making or receiving payment in accordance with normal procedures for same-day
funds settlement applicable to DTC. Euroclear participants and Cedel Bank
participants may not deliver instructions directly to the depositaries for
Euroclear or Cedel Bank.



    Because of time zone differences, the securities account of a Euroclear or
Cedel Bank participant purchasing an interest in a global security from a
participant in DTC will be credited, and any such crediting will be reported to
the relevant Euroclear or Cedel Bank participant, during the securities
settlement processing day immediately following the settlement date of DTC. The
securities settlement processing day must be a business day for Euroclear and
Cedel Bank. Cash received in Euroclear or Cedel Bank as a result of sales of an
interest in a global note by or through a Euroclear or Cedel Bank participant to
a DTC participant will be received with value on the settlement date of DTC but
will be available in the relevant Euroclear or Cedel Bank cash account only as
of the business day for Euroclear or Cedel Bank following DTC's settlement date.


                                       92
<PAGE>

    Carrier1 International expects DTC, Euroclear and Cedel Bank to follow these
procedures to facilitate transfers of interests in the global notes among
participants in DTC, Euroclear and Cedel Bank. These organizations, however, are
under no obligation to perform or to continue to perform these procedures. They
may discontinue them at any time. None of Carrier1 International, any trustee or
any paying agent will have any responsibility for the performance by DTC,
Euroclear and Cedel Bank or their participants or indirect participants of their
obligations under the rules and procedures governing their operations.


    CERTIFICATED SECURITIES


    In some circumstances specified in the indentures, Carrier1 International
will issue certified notes in exchange for the global notes. Certificated notes
representing old notes would be subject to transfer restrictions.


OPTIONAL REDEMPTION


    Carrier1 International may opt to redeem the notes, in whole or in part, at
any time on or after February 15, 2004. If Carrier1 International chooses this
optional redemption, it is required to provide a notice of the redemption not
les than 30 and not more than 60 days prior to the redemption. If redeemed
during the twelve-month period beginning on February 15 of the years set forth
below, the notes may be redeemed at the following Redemption Prices, which are
expressed as percentages of the principal amount, plus accrued and unpaid
interest:


<TABLE>
<CAPTION>
YEAR                                                                          REDEMPTION PRICE
- ----------------------------------------------------------------------------  ----------------
<S>                                                                           <C>
2004........................................................................        106.625%
2005........................................................................        104.417
2006........................................................................        102.208
2007 and thereafter.........................................................        100.000
</TABLE>


    In addition, at any time prior to February 15, 2002, Carrier1 International
may redeem notes of either series in an aggregate principal amount equal to up
to 35% of the principal amount of the dollar notes or Euro notes, as the case
may be, with funds in an amount equal to the proceeds of one or more sales of
Capital Stock (other than Disqualified Stock) of, or capital contributions to,
Carrier1 International. If Carrier1 International chooses this optional
redemption, it may redeem either series of notes, at any time and from time to
time in part, at a Redemption Price of 113.25%, expressed as a percentage of
principal amount, plus accrued and unpaid interest to the Redemption Date.
Carrier1 may make any such redemption if:



        (1) an aggregate principal amount equal to at least 65% of the principal
    amount of the initially issued dollar notes or Euro notes, as the case may
    be, plus the principal amount of any Additional Notes of such series remains
    outstanding after each such redemption, and



        (2) notice of any such redemption is provided within 60 days of each
    such sale or capital contribution.



    For any partial redemption, the relevant trustee will select the notes for
redemption by a method specified in the relevant indenture. However, no dollar
note of $1,000 in principal amount or less or Euro note of [Euro]1,000 in
principal amount or less shall be redeemed in part. If any note is to be
redeemed in part only, the notice of redemption relating to such note shall
state the portion of the principal amount to be redeemed. A new note in
principal amount equal to the unredeemed portion will be issued in the name of
the relevant holder upon cancellation of the original note.


                                       93
<PAGE>
    In the event that


        (1) as a result of any change in, or amendments to, any laws or treaties
    (or any regulations or rulings promulgated thereunder) or any change in
    official position regarding the application of such laws, treaties,
    regulations or rulings (including a holding, judgment or order by a court of
    competent jurisdiction), which change, amendment, application or
    interpretation becomes effective after the Closing Date, Carrier1
    International has become or would become obligated to pay, on the next date
    on which any amount would be payable under or with respect to the notes, any
    Additional Amounts (as defined herein), and



        (2) Carrier1 International cannot reasonably arrange (without other
    material adverse consequences to Carrier1 International) for another obligor
    to make such payment so as to avoid the requirement to pay such Additional
    Amounts,



then Carrier1 International may redeem all the notes at any time at 100% of the
principal amount thereof, together with accrued interest thereon, if any, to the
redemption date. See "--Additional Amounts."


SINKING FUND


    There will be no sinking fund payments for the notes.


REGISTRATION RIGHTS


    Carrier1 International has agreed to use its best efforts to file a
registration statement for this exchange offer and cause it to become effective.
The registration statement of which this prospectus is a part constitutes the
registration statement to be filed pursuant to this registration rights
agreement.



    If applicable interpretations of the staff of the United States Securities
and Exchange Commission (the "Commission") do not permit Carrier1 International
to effect the exchange offer, Carrier1 International shall use its best efforts
to cause a shelf registration statement with respect to resales of each series
of old notes to become effective. Carrier1 shall also use its best efforts to
keep the shelf registration statement effective for time periods specified in
the registration rights agreement. Carrier1 International shall, in the event of
a shelf registration, provide to each holder copies of the prospectus and notify
each holder when the shelf registration statement has become effective. Carrier1
International generally will be required to name a holder that sells its notes
pursuant to a shelf registration statement as a selling security holder in the
related prospectus and to deliver a prospectus to purchasers. Civil liability
provisions under the Securities Act will apply to such a selling holder in
connection with such sales. Provisions of the registration rights agreement will
also apply to such a holder (including indemnification obligations of holders).



    If the exchange offer is not consummated and a shelf registration statement
is not declared effective with respect to either series of old notes on or prior
to the date that is six months after the date of the original offering of the
old notes, the interest rate borne for such series of old notes will be
increased by 0.5% per annum until the exchange offer is consummated or the shelf
registration statement is declared effective.


                                       94
<PAGE>

    This is a summary of the material provisions of the registration rights
agreement. It does not purport to be complete. It is subject to, and is
qualified in its entirety by reference to, all the provisions of the
registration rights agreement. A copy of the registration rights agreement is
available as set forth under the heading "Where You Can Find More Information."



SECURITY



    Carrier1 International has pledged the Pledged Securities to the relevant
trustee for the benefit of the holders of the relevant notes to pay the first
five scheduled interest payments due on the notes. Carrier1 International used
approximately $49.2 million and [Euro]26.9 million of the original offering to
acquire the Pledged Securities.



    Before an Interest Payment Date on the notes, Carrier1 International may
either (a) deposit cash to pay the interest scheduled for that date or (b)
direct the trustee to release proceeds from the relevant Pledge Account to pay
such interest. If Carrier1 International exercises the former option, it may
direct the trustee to release to it an equal amount of proceeds or Pledged
Securities from the relevant Pledge Account. A failure by Carrier1 International
to pay interest for the first five interest payment dates will be an immediate
Event of Default under the applicable indenture, with no grace or cure period.



    Each series of notes is secured in part by the applicable Pledged Securities
and the applicable Pledge Account maintained with an affiliate of the relevant
trustee as securities intermediary (the "Securities Intermediary"). Once
Carrier1 International makes the first five scheduled interest payments on the
notes, all of the remaining Pledged Securities and any other amounts in the
Pledge Accounts, if any, will be released from the Pledge Accounts. Thereafter,
the notes will be unsecured.


RANKING


    The debt evidenced by the notes will rank PARI PASSU in right of payment
with all existing and future unsubordinated indebtedness of Carrier1
International and senior in right of payment to all subordinated indebtedness of
Carrier1 International. As of March 31, 1999, Carrier1 International had no
indebtedness outstanding other than the notes of both series and had current
liabilities of $4.2 million. In addition, all existing and future liabilities
(including trade payables) of Carrier1 International's subsidiaries will be
effectively senior to the notes. As of March 31, 1999, Carrier1 International's
subsidiaries had $47.1 million of current liabilities, including trade payables.


CERTAIN DEFINITIONS


    Set forth below is a summary of certain of the defined terms used in the
covenants and other provisions of the indentures. Reference is made to the
indentures for the definition of any other capitalized term used herein for
which no definition is provided.


    "Acquired Indebtedness" means Indebtedness of a Person existing at the time
such Person becomes a Restricted Subsidiary or is merged with or consolidated
with a Restricted Subsidiary or assumed in connection with an Asset Acquisition
by a Restricted Subsidiary and not Incurred in connection with, or in
anticipation of, such Person becoming a Restricted Subsidiary or such Asset
Acquisition.


    "Adjusted Consolidated Net Income" means, for any period, the aggregate net
income (or loss) of Carrier1 International and its Restricted Subsidiaries for
such period determined on a consolidated basis in conformity with GAAP; PROVIDED
that the following items shall be excluded in computing Adjusted Consolidated
Net Income (without duplication):



        (1) the net income (or loss) of any Person that is not a Restricted
    Subsidiary, except (x) with respect to net income, to the extent of the
    amount of dividends or other distributions actually paid to Carrier1
    International or any of its Restricted Subsidiaries by such Person during
    such period and


                                       95
<PAGE>

    (y) with respect to net losses, to the extent of the amount of Investments
    made by Carrier1 International or any Restricted Subsidiary in such Person
    during such period;



        (2) solely for the purposes of calculating the amount of Restricted
    Payments that may be made pursuant to clause (C) of the first paragraph of
    the "Limitation on Restricted Payments" covenant described below (and in
    such case, except to the extent includable pursuant to clause (1) above),
    the net income (or loss) of any Person accrued prior to the date it becomes
    a Restricted Subsidiary or is merged into or consolidated with Carrier1
    International or any of its Restricted Subsidiaries or all or substantially
    all of the property and assets of such Person are acquired by Carrier1
    International or any of its Restricted Subsidiaries;



        (3) the net income of any Restricted Subsidiary other than a Permanent
    Guarantor to the extent that the declaration or payment of dividends or
    similar distributions by such Restricted Subsidiary of such net income is
    not at the time permitted (after giving effect to any effective waiver,
    consent or approval) by the operation of the terms of its charter or any
    agreement, instrument, judgment, decree, order, statute, rule or
    governmental regulation applicable to such Restricted Subsidiary;



        (4) any gains or losses attributable to Asset Sales (without regard to
    clause (c) or (d) in the proviso to the definition thereof);



        (5) solely for purposes of calculating the amount of Restricted Payments
    that may be made pursuant to clause (C) of the first paragraph of the
    "Limitation on Restricted Payments" covenant described below, any amount
    paid or accrued as dividends on Preferred Stock of Carrier1 International or
    any Restricted Subsidiary owned by Persons other than Carrier1 International
    and any of its Restricted Subsidiaries;



        (6) all extraordinary gains and extraordinary losses or extraordinary
    charges;



        (7) any compensation expense to the extent paid or payable solely with
    Capital Stock (other than Disqualified Stock) of Carrier1 International or
    any options, warrants or other rights to acquire Capital Stock (other than
    Disqualified Stock) of Carrier1 International; and



        (8) the cumulative effect of a change in accounting principles.



    "Adjusted Consolidated Net Tangible Assets" means the total amount of assets
of Carrier1 International and its Restricted Subsidiaries (less applicable
depreciation, amortization and other valuation reserves), except to the extent
resulting from write-ups of capital assets (excluding write-ups in connection
with accounting for acquisitions in conformity with GAAP), after deducting
therefrom:



        (1) all current liabilities of Carrier1 International and its Restricted
    Subsidiaries (excluding intercompany items) and



        (2) all goodwill, trade names, trademarks, patents, unamortized debt
    discount and expense and other like intangibles,



all as set forth on the most recent quarterly or annual consolidated balance
sheet of Carrier1 International and its Restricted Subsidiaries, prepared in
conformity with GAAP and filed with the Commission or provided to the relevant
trustee pursuant to the "Commission Reports and Reports to Holders" covenant.


    "Affiliate" means, as applied to any Person, any other Person directly or
indirectly controlling, controlled by, or under direct or indirect common
control with, such Person. For purposes of this definition, "control"
(including, with correlative meanings, the terms "controlling," "controlled by"
and "under common control with"), as applied to any Person, means the
possession, directly or indirectly, of the power to direct or cause the
direction of the management and policies of such Person, whether through the
ownership of voting securities, by contract or otherwise.

                                       96
<PAGE>
    "Asset Acquisition" means:


        (1) an investment by Carrier1 International or any of its Restricted
    Subsidiaries in any other Person pursuant to which such Person shall become
    a Restricted Subsidiary or shall be merged into or consolidated with
    Carrier1 International or any of its Restricted Subsidiaries; PROVIDED that
    such Person's primary business is related, ancillary or complementary to the
    businesses of Carrier1 International and its Restricted Subsidiaries on the
    date of such investment, as determined in good faith by the Board of
    Directors (whose determination shall be conclusive and evidenced by a Board
    Resolution) or



        (2) an acquisition by Carrier1 International or any of its Restricted
    Subsidiaries of the property and assets of any Person other than Carrier1
    International or any of its Restricted Subsidiaries that constitute
    substantially all of a division or line of business of such Person; PROVIDED
    that the property and assets acquired are related, ancillary or
    complementary to the businesses of Carrier1 International and its Restricted
    Subsidiaries on the date of such acquisition, as determined in good faith by
    the Board of Directors (whose determination shall be conclusive and
    evidenced by a Board Resolution).



    "Asset Disposition" means the sale or other disposition by Carrier1
International or any of its Restricted Subsidiaries (other than to Carrier1
International or another Restricted Subsidiary) of:



        (1) all or substantially all of the Capital Stock of any Restricted
    Subsidiary or



        (2) all or substantially all of the assets that constitute a division or
    line of business of Carrier1 International or any of its Restricted
    Subsidiaries.



    "Asset Sale" means any sale, transfer or other disposition (including by way
of merger, consolidation or sale-leaseback transaction) in one transaction or a
series of related transactions by Carrier1 International or any of its
Restricted Subsidiaries to any Person other than Carrier1 International or any
of its Restricted Subsidiaries of:



        (1) all or any of the Capital Stock of any Restricted Subsidiary,



        (2) all or substantially all of the property and assets of an operating
    unit or business of Carrier1 International or any of its Restricted
    Subsidiaries or



        (3) any other property and assets (other than the Capital Stock of or
    any other Investment in an Unrestricted Subsidiary) of Carrier1
    International or any of its Restricted Subsidiaries outside the ordinary
    course of business of Carrier1 International or such Restricted Subsidiary
    and, in each case, that is not governed by the provisions of the relevant
    indenture applicable to mergers, consolidations and sales of all or
    substantially all of the assets of Carrier1 International;


PROVIDED that "Asset Sale" shall not include:

        (a) sales, transfers or other dispositions of Temporary Cash
    Investments, inventory, receivables and other current assets,

        (b) sales, transfers or other dispositions of assets constituting a
    Restricted Payment (or a transaction excluded from the definition of the
    term "Restricted Payments") permitted to be made under the "Limitation on
    Restricted Payments" covenant,

        (c) sales, transfers or other dispositions of assets with a fair market
    value (as certified in an Officers' Certificate) not in excess of $2 million
    in any transaction or series of related transactions, or

        (d) sales or other dispositions of assets for consideration at least
    equal to the fair market value of the assets sold or disposed of, to the
    extent that the consideration received would constitute property or assets
    of the kind described in clause (B) of the second paragraph of the
    "Limitation on Asset Sales" covenant.

                                       97
<PAGE>

    "Average Life" means, at any date of determination with respect to any
Indebtedness, the quotient obtained by dividing (1) the sum of the products of
(a) the number of years from such date of determination to the dates of each
successive scheduled principal payment of such Indebtedness and (b) the amount
of such principal payment by (2) the sum of all such principal payments.


    "Capital Stock" means, with respect to any Person, any and all shares,
interests, participations or other equivalents (however designated, whether
voting or non-voting) in equity of such Person, whether outstanding on the
Closing Date or issued thereafter, including, without limitation, all Common
Stock and Preferred Stock.

    "Capitalized Lease" means, as applied to any Person, any lease of any
property (whether real, personal or mixed) of which the discounted present value
of the rental obligations of such Person as lessee, in conformity with GAAP, is
required to be capitalized on the balance sheet of such Person.

    "Capitalized Lease Obligations" means the discounted present value of the
rental obligations under a Capitalized Lease.

    "Change of Control" means such time as:


        (1) a "person" or "group" (within the meaning of Section 13(d) or
    14(d)(2) under the Exchange Act) becomes the ultimate "beneficial owner" (as
    defined in Rule 13d-3 under the Exchange Act) of more than 35% (50%, if the
    Permitted Holders hold more than 35% of the voting power of the Voting Stock
    of Carrier1 International on a fully diluted basis) of the total voting
    power of the Voting Stock of Carrier1 International on a fully diluted basis
    and such ownership represents a greater percentage of the total voting power
    of the Voting Stock of Carrier1 International, on a fully diluted basis,
    than is held by Permitted Holders on such date; or



        (2) during any period of two consecutive years beginning on or after the
    Closing Date, individuals who at the beginning of such period were members
    of the Board of Directors (together with any new directors whose election by
    the Board of Directors or whose nomination for election by Carrier1
    International's shareholders was approved by a vote of at least a majority
    of the members of the Board of Directors then in office who either were
    members of the Board of Directors at the beginning of such period or whose
    election or nomination for election was previously so approved) cease for
    any reason to constitute a majority of the members of the Board of Directors
    then in office.



    "Closing Date" means the date on which the notes are first issued under the
indentures.


    "Common Stock" means, with respect to any Person, any and all shares,
interests, participations or other equivalents (however designated, whether
voting or non-voting) of such Person's equity, other than Preferred Stock of
such Person, whether outstanding on the Closing Date or issued thereafter,
including, without limitation all series and classes of such common stock.

    "Consolidated EBITDA" means, for any period, Adjusted Consolidated Net
Income for such period plus, to the extent such amount was deducted in
calculating such Adjusted Consolidated Net Income,


        (1) Consolidated Interest Expense,



        (2) provision for all taxes based on income, profits or capital,



        (3) depreciation expense,



        (4) amortization expense (including but not limited to amortization of
    goodwill and intangibles and amortization and write-off of financing costs)
    and



        (5) all other non-cash items reducing Adjusted Consolidated Net Income
    (other than items that will require cash payments and for which an accrual
    or reserve is, or is required by GAAP to be, made), less all non-cash items
    increasing Adjusted Consolidated Net Income (other than any item reversing,
    offsetting or reducing any such accrual or reserve),


                                       98
<PAGE>

all as determined on a consolidated basis for Carrier1 International and its
Restricted Subsidiaries in conformity with GAAP; PROVIDED that, if any
Restricted Subsidiary is not a Wholly Owned Restricted Subsidiary, Consolidated
EBITDA shall be reduced (to the extent not otherwise reduced in accordance with
GAAP) by an amount equal to



        (A) the amount of the Adjusted Consolidated Net Income attributable to
    such Restricted Subsidiary multiplied by



        (B) the percentage ownership interest in the income of such Restricted
    Subsidiary not owned on the last day of such period by Carrier1
    International or any of its Restricted Subsidiaries.



    "Consolidated Interest Expense" means, for any period, the aggregate amount
of interest in respect of Indebtedness (including, without limitation,
amortization of original issue discount on any Indebtedness and the interest
portion of any deferred payment obligation, calculated in accordance with the
effective interest method of accounting; all commissions, discounts and other
fees and charges owed with respect to letters of credit and bankers' acceptance
financing; the net costs associated with Interest Rate Agreements; and interest
on Indebtedness that is Guaranteed or secured by Carrier1 International or any
of its Restricted Subsidiaries) and the interest component of Capitalized Lease
Obligations paid, accrued or scheduled to be paid or to be accrued by Carrier1
International and its Restricted Subsidiaries during such period, all as
determined on a consolidated basis (without taking into account Unrestricted
Subsidiaries) in conformity with GAAP.


    "Consolidated Leverage Ratio" means, on any Transaction Date, the ratio of:


        (1) the aggregate amount of Indebtedness of Carrier1 International and
    its Restricted Subsidiaries on a consolidated basis outstanding on such
    Transaction Date to



        (2) four times the amount of Consolidated EBITDA for the then most
    recent fiscal quarter for which financial statements of Carrier1
    International have been filed with the Commission or provided to the
    relevant trustee pursuant to the "Commission Reports and Reports to Holders"
    covenant described below (such quarter being the "Quarter");


PROVIDED that, in making the foregoing calculation:

        (A) PRO FORMA effect shall be given, in calculating the amount of
    Indebtedness outstanding on the Transaction Date, to any Indebtedness to be
    Incurred on the Transaction Date, or to be repaid, repurchased, redeemed or
    otherwise retired or discharged on the Transaction Date;

        (B) PRO FORMA effect shall be given to Asset Dispositions and Asset
    Acquisitions (including giving PRO FORMA effect to the application of
    proceeds of any Asset Disposition) that occur from the beginning of the
    Quarter through the Transaction Date (the "Reference Period"), as if they
    had occurred and such proceeds had been applied on the first day of such
    Reference Period; and


        (C) PRO FORMA effect shall be given to asset dispositions and asset
    acquisitions (including giving PRO FORMA effect to the application of
    proceeds of any asset disposition) that have been made by any Person that
    has become a Restricted Subsidiary or has been merged with or into, or
    consolidated with, Carrier1 International or any Restricted Subsidiary
    during such Reference Period and that would have constituted Asset
    Dispositions or Asset Acquisitions had such transactions occurred when such
    Person was a Restricted Subsidiary as if such asset dispositions or asset
    acquisitions were Asset Dispositions or Asset Acquisitions that occurred on
    the first day of such Reference Period;


PROVIDED that to the extent that clause (B) or (C) of this sentence requires
that PRO FORMA effect be given to an Asset Acquisition or Asset Disposition,
such PRO FORMA calculation shall be based upon the full fiscal quarter
immediately preceding the Transaction Date of the Person, or division or line of
business of the Person, that is acquired or disposed of for which financial
information is available.

                                       99
<PAGE>

    "Consolidated Net Worth" means, at any date of determination, shareholders'
equity (plus, to the extent not otherwise included, Preferred Stock of Carrier1
International) as set forth on the most recently available quarterly or annual
consolidated balance sheet of Carrier1 International and its Restricted
Subsidiaries (which shall be as of a date not more than 90 days prior to the
date of such computation, and which shall not take into account Unrestricted
Subsidiaries), less any amounts attributable to Disqualified Stock or any equity
security convertible into or exchangeable for Indebtedness, the cost of treasury
stock and the principal amount of any promissory notes receivable from the sale
of the Capital Stock of Carrier1 International or any of its Restricted
Subsidiaries, each item to be determined in conformity with GAAP (excluding the
effects of foreign currency exchange adjustments under Financial Accounting
Standards Board Statement of Financial Accounting Standards No. 52).


    "Currency Agreement" means any foreign exchange contract, currency swap
agreement or other similar agreement or arrangement.

    "Default" means any event that is, or after notice or passage of time or
both would be, an Event of Default.


    "disinterested member" means, with respect to any transaction, a member of
the Board of Directors having no material financial interest in or with respect
to such transaction. A member of the Board of Directors shall not be deemed to
have such a financial interest solely by reason of such member's holding Capital
Stock of Carrier1 International or any parent thereof or any options, warrants
or other rights in respect of such Capital Stock.


    "Disqualified Stock" means any class or series of Capital Stock of any
Person that by its terms or otherwise is:


        (1) required to be redeemed prior to the Stated Maturity of the notes,



        (2) redeemable at the option of the holder of such class or series of
    Capital Stock at any time prior to the Stated Maturity of the notes or



        (3) convertible into or exchangeable for Capital Stock referred to in
    clause (1) or (2) above or Indebtedness having a scheduled maturity prior to
    the Stated Maturity of the notes;



PROVIDED that any Capital Stock that would not constitute Disqualified Stock but
for provisions thereof giving holders thereof the right to require such Person
to repurchase or redeem such Capital Stock upon the occurrence of an "asset
sale" or "change of control" occurring prior to the Stated Maturity of the notes
shall not constitute Disqualified Stock if the "asset sale" or "change of
control" provisions applicable to such Capital Stock are no more favorable to
the holders of such Capital Stock than the provisions contained in "Limitation
on Asset Sales" and "Repurchase of Notes upon a Change of Control" covenants
described below and such Capital Stock, or the agreements or instruments
governing the redemption rights thereof, specifically provides that such Person
will not repurchase or redeem any such stock pursuant to such provision prior to
Carrier1 International's repurchase of such notes as are required to be
repurchased pursuant to the "Limitation on Asset Sales" and "Repurchase of Notes
upon a Change of Control" covenants described below.


    "European Government Obligations" means securities that are direct and
unconditional obligations of the Belgian, Dutch, French, German or Swiss
government and are not callable or redeemable at the option of the issuer
thereof; provided that at the time of determination the conversion rate between
the sovereign currency of such country and the Euro is fixed and shall also
include a depository receipt issued by a bank or trust company as custodian with
respect to any such European Government Obligation or a specific payment of
interest on or principal of any such European Government Obligation held by such
custodian for the account of the holder of a depository receipt; PROVIDED that
(except as required by law) such custodian is not authorized to make any
deduction from the amount payable to the holder of such depository receipt from
any amount received by the custodian in respect of the European Government

                                      100
<PAGE>
Obligation or the specific payment of interest on or principal of the European
Government Obligation evidenced by such depository receipt.


    "European Government Securities" means securities that are direct and
unconditional obligations of the German government meeting the requirements of
the Pledge Agreement relating to the Euro notes.


    "European Union" means the European Union, including the countries of
Austria, Belgium, Denmark, France, Finland, Germany, Greece, Ireland, Italy,
Luxembourg, The Netherlands, Portugal, Spain, Sweden, and the United Kingdom; as
well as any other country which at the time of determination is a member of the
European Union.


    "fair market value" means the price that would be paid in an arm's-length
transaction between an informed and willing seller under no compulsion to sell
and an informed and willing buyer under no compulsion to buy, as determined in
good faith by the Board of Directors, whose determination shall be conclusive if
evidenced by a Board Resolution; PROVIDED that for purposes of clause (8) of the
second paragraph of the "Limitation on Indebtedness" covenant,


        (x) the fair market value of any security registered under the Exchange
    Act shall be the average of the closing prices, regular way, of such
    security for the 20 consecutive trading days immediately preceding the sale
    of Capital Stock and


        (y) in the event the aggregate fair market value of any other property
    (other than cash or cash equivalents) received by Carrier1 International
    exceeds $10 million, the fair market value of such property shall be
    determined by a nationally recognized investment banking or appraisal firm
    and set forth in their written opinion which shall be delivered to the
    relevant trustee.



    "GAAP" means generally accepted accounting principles in the United States
of America as in effect as of the Closing Date, including, without limitation,
those set forth in the opinions and pronouncements of the Accounting Principles
Board of the American Institute of Certified Public Accountants and statements
and pronouncements of the Financial Accounting Standards Board or in such other
statements by such other entity as approved by a significant segment of the
accounting profession; PROVIDED, HOWEVER, that all reports and other financial
information provided by Carrier1 International to the holders of the relevant
series of notes or the relevant trustee shall be prepared in accordance with
GAAP as in effect from time to time. All ratios and computations contained or
referred to in the relevant Indenture shall be computed in conformity with GAAP
applied on a consistent basis, except that calculations made for purposes of
determining compliance with the terms of the covenants and with other provisions
of the relevant indenture shall be made without giving effect to (1) the
amortization or write-off of any expenses incurred in connection with the
offering of the Units and (2) the amortization of any amounts required or
permitted by Accounting Principles Board Opinion Nos. 16 and 17.



    "German Network" means the fiber optic network to be built in Germany by
Carrier1 International or any of its Restricted Subsidiaries with affiliates of
Viatel, Inc. and Metromedia Fiber Network Inc. contemplated by the letter of
intent dated August 20, 1998.



    "German Network L/C" means a letter of credit in an amount not to exceed $75
million issued to secure obligations of Carrier1 International or any of its
Restricted Subsidiaries with respect to the German Network.


    "Guarantee" means any obligation, contingent or otherwise, of any Person
directly or indirectly guaranteeing any Indebtedness of any other Person and,
without limiting the generality of the foregoing, any such obligation, direct or
indirect, contingent or otherwise, of such Person:


        (1) to purchase or pay (or advance or supply funds for the purchase or
    payment of) such Indebtedness of such other Person (whether arising by
    virtue of partnership arrangements, or by agreements to keep-well, to
    purchase assets, goods, securities or services (unless such purchase


                                      101
<PAGE>
    arrangements are on arm's-length terms and are entered into in the ordinary
    course of business), to take-or-pay, or to maintain financial statement
    conditions or otherwise) or


        (2) entered into for purposes of assuring in any other manner the
    obligee of such Indebtedness of the payment thereof or to protect such
    obligee against loss in respect thereof (in whole or in part);


PROVIDED that the term "Guarantee" shall not include endorsements for collection
or deposit in the ordinary course of business. The term "Guarantee" used as a
verb has a corresponding meaning.

    "Incur" means, with respect to any Indebtedness, to incur, create, issue,
assume, enter into any Guarantee of or otherwise become liable for or with
respect to, or become responsible for, the payment of, contingently or
otherwise, such Indebtedness, including an "Incurrence" by means of the
acquisition of more than 50% of the Capital Stock of any Person; PROVIDED that
neither the accrual of interest nor the accretion of original issue discount
shall be considered an Incurrence of Indebtedness.

    "Indebtedness" means, with respect to any Person at any date of
determination (without duplication):


        (1) all indebtedness of such Person for borrowed money;



        (2) all principal obligations of such Person evidenced by bonds,
    debentures, notes or other similar instruments;



        (3) all reimbursement obligations of such Person in respect of letters
    of credit or other similar instruments (excluding obligations with respect
    to letters of credit (including trade letters of credit) or other similar
    instruments securing obligations (other than obligations described in (1) or
    (2) above or (5), (6) or (7) below) entered into in the ordinary course of
    business of such Person to the extent such letters of credit are not
    properly honored and drawn upon or, if properly honored and drawn upon, to
    the extent such drawing is reimbursed no later than the third Business Day
    following receipt by such Person of a demand for reimbursement);



        (4) all obligations of such Person to pay the deferred and unpaid
    purchase price of property or services, which purchase price is due more
    than six months after the date of placing such property in service or taking
    delivery and title thereto or the completion of such services, except Trade
    Payables;



        (5) all Capitalized Lease Obligations of such Person;



        (6) all Indebtedness of other Persons secured by a Lien on any asset of
    such Person, whether or not such Indebtedness is assumed by such Person;
    PROVIDED that the amount of such Indebtedness of such Person shall be the
    lesser of (A) the fair market value of such asset at such date of
    determination and (B) the amount of such Indebtedness of such other Persons;



        (7) all Indebtedness of other Persons Guaranteed by such Person;
    provided that the amount of Indebtedness of such Person shall be the lesser
    of (A) the amount Guaranteed and (B) the amount of such Indebtedness of such
    other Persons; and



        (8) to the extent not otherwise included in this definition, obligations
    under Currency Agreements and Interest Rate Agreements, except if such
    agreements



           (a) are designed solely to protect Carrier1 International or its
       Restricted Subsidiaries against fluctuations in foreign currency exchange
       rates or interest rates and


           (b) do not increase the Indebtedness of the obligor outstanding at
       any time other than as a result of fluctuations in foreign currency
       exchange rates or interest rates or by reason of fees, indemnities and
       compensation payable thereunder.

    The amount of Indebtedness of any Person as described above at any date
shall be the outstanding balance at such date of all unconditional obligations
as described above and, with respect to contingent

                                      102
<PAGE>
obligations as described above, the maximum liability upon the occurrence of the
contingency giving rise to the obligation, provided:

        (A) that the amount outstanding at any time of any Indebtedness issued
    with original issue discount is the face amount of such Indebtedness less
    the remaining unamortized portion of the original issue discount of such
    Indebtedness at the time of its issuance as determined in conformity with
    GAAP,

        (B) that obligations for money borrowed and set aside at the time of the
    Incurrence of any Indebtedness in order to prefund the payment of the
    interest on such Indebtedness shall not be deemed to be "Indebtedness" so
    long as such money is held to secure the payment of such interest,

        (C) that the amount of an obligation in respect of a letter of credit or
    other similar instrument is the aggregate undrawn and unexpired amount
    thereof plus the aggregate amount of drawings properly honored thereunder
    that have not then been reimbursed, and

        (D) that "Indebtedness" shall not include any liability for federal,
    state, local or other taxes.

    Indebtedness shall not be deemed to include any obligation arising from the
honoring of a check, draft or similar instrument drawn against insufficient
funds, provided that such obligation is extinguished within five business days
of its Incurrence.

    "Interest Rate Agreement" means any interest rate protection agreement,
interest rate future agreement, interest rate option agreement, interest rate
swap agreement, interest rate cap agreement, interest rate collar agreement,
interest rate hedge agreement, option or future contract or other similar
agreement or arrangement.


    "Investment" in any Person means any direct or indirect advance, loan or
other extension of credit (including, without limitation, by way of Guarantee or
similar arrangement; but excluding advances, loans or other extensions of credit
to customers or suppliers in the ordinary course of business to the extent
required by GAAP to be recorded as accounts receivable, prepaid expenses or
deposits on the balance sheet of Carrier1 International or its Restricted
Subsidiaries) or capital contribution to (by means of any transfer of cash or
other property to others or any payment for property or services for the account
or use of others), or any purchase or acquisition of Capital Stock, bonds,
notes, debentures or other similar instruments issued by, such Person and shall
include:



        (1) the designation of a Restricted Subsidiary as an Unrestricted
    Subsidiary and



        (2) the fair market value of the Capital Stock (or any other
    Investment), held by Carrier1 International or any of its Restricted
    Subsidiaries, of (or in) any Person that has ceased to be a Restricted
    Subsidiary, including without limitation, by reason of any transaction
    permitted by clause (3) of the "Limitation on the Issuance and Sale of
    Capital Stock of Restricted Subsidiaries" covenant;


PROVIDED that the fair market value of the Investment remaining in any Person
that has ceased to be a Restricted Subsidiary shall not exceed the aggregate
amount of Investments previously made in such Person valued at the time such
Investments were made less the net reduction of such Investments. For purposes
of the definition of "Unrestricted Subsidiary" and the "Limitation on Restricted
Payments" covenant described below:


        (1) "Investment" shall include the fair market value of the assets (net
    of liabilities (other than liabilities to Carrier1 International or any of
    its Restricted Subsidiaries)) of any Restricted Subsidiary at the time that
    such Restricted Subsidiary is designated an Unrestricted Subsidiary,


                                      103
<PAGE>

        (2) the fair market value of the assets (net of liabilities (other than
    liabilities to Carrier1 International or any of its Restricted
    Subsidiaries)) of any Unrestricted Subsidiary at the time that such
    Unrestricted Subsidiary is designated a Restricted Subsidiary shall be
    considered a reduction in outstanding Investments and



        (3) any property transferred to or from an Unrestricted Subsidiary shall
    be valued at its fair market value at the time of such transfer.


    "Lien" means any mortgage, pledge, security interest, encumbrance, lien or
charge of any kind (including, without limitation, any conditional sale or other
title retention agreement or lease in the nature thereof or any agreement to
give any security interest).


    "Management Investor" means any officer, director, employee or other member
of the management of Carrier1 International or any of its Subsidiaries, or
family members or relatives thereof, or trusts or partnerships for the benefit
of any of the foregoing, or any of their heirs, executors, successors and legal
representatives.


    "Moody's" means Moody's Investors Service, Inc. and its successors.

    "Net Cash Proceeds" means:


        (a) with respect to any Asset Sale, the proceeds of such Asset Sale when
    received in the form of cash or cash equivalents, including payments in
    respect of deferred payment obligations (to the extent corresponding to the
    principal, but not interest, component thereof) when received in the form of
    cash or cash equivalents (except to the extent such obligations are financed
    or sold with recourse to Carrier1 International or any Restricted
    Subsidiary) and proceeds from the conversion of other property received when
    converted to cash or cash equivalents, net of



           (1) brokerage commissions and other fees and expenses (including fees
       and expenses of counsel and investment bankers) related to such Asset
       Sale,



           (2) provisions for all taxes (whether or not such taxes will actually
       be paid or are payable) as a result of such Asset Sale without regard to
       the consolidated results of operations of Carrier1 International and its
       Restricted Subsidiaries, taken as a whole, including as a consequence of
       any transfer of funds in connection with the application thereof in
       accordance with the "Limitation on Asset Sales" covenant,



           (3) payments made, or required to be made, to repay Indebtedness or
       any other obligation outstanding at the time of such Asset Sale that
       either (A) is secured by a Lien on the property or assets sold or (B) is
       required to be paid as a result of such Asset Sale,



           (4) all distributions and other payments required to be made to
       minority interest holders in a Restricted Subsidiary or joint venture as
       a result of such Asset Sale by or of such Restricted Subsidiary or joint
       venture, or to any other Person (other than Carrier1 International or a
       Restricted Subsidiary) owning a beneficial interest in the assets
       disposed of in such Asset Sale, and



           (5) appropriate amounts to be provided by Carrier1 International or
       any Restricted Subsidiary as a reserve against any liabilities or
       obligations associated with such Asset Sale, including, without
       limitation, pension and other post-employment benefit liabilities,
       liabilities related to environmental matters and liabilities under any
       indemnification obligations associated with such Asset Sale, all as
       determined in conformity with GAAP and


                                      104
<PAGE>

        (b) with respect to any issuance or sale of Capital Stock, the proceeds
    of such issuance or sale in the form of cash or cash equivalents, including
    payments in respect of deferred payment obligations (to the extent
    corresponding to the principal, but not interest, component thereof) when
    received in the form of cash or cash equivalents (except to the extent such
    obligations are financed or sold with recourse to Carrier1 International or
    any Restricted Subsidiary) and proceeds from the conversion of other
    property received when converted to cash or cash equivalents, net of
    attorney's fees, accountants' fees, underwriters' or placement agents' fees,
    discounts or commissions and brokerage, consultant and other fees incurred
    in connection with such issuance or sale and net of taxes paid or payable as
    a result thereof.



    In the event that any consideration for any Asset Sale that would otherwise
constitute Net Cash Proceeds is required to be held in escrow pending
determination of whether a purchase price adjustment, indemnification or other
payment or other similar adjustment will be made, such consideration will become
Net Cash Proceeds only when and to the extent released from escrow to Carrier1
International or a Restricted Subsidiary.



    "Offer to Purchase" means an offer to purchase notes by Carrier1
International from the holders commenced by mailing a notice to the relevant
trustee and providing notice to each holder stating:



        (1) the covenant pursuant to which the offer is being made and that all
    notes validly tendered will be accepted for payment on a pro rata basis;



        (2) the purchase price and the date of purchase (which shall be a
    Business Day no earlier than 30 days nor later than 60 days from the date
    such notice is mailed) (the "Payment Date");



        (3) that any note not tendered will continue to accrue interest pursuant
    to its terms;



        (4) that, unless Carrier1 International defaults in the payment of the
    purchase price, any note accepted for payment pursuant to the Offer to
    Purchase shall cease to accrue interest on and after the Payment Date;



        (5) that holders electing to have a note purchased pursuant to the Offer
    to Purchase will be required to surrender the note, together with the form
    entitled "Option of the holder to Elect Purchase" on the reverse side of the
    note completed, to the Paying Agent at the address specified in the notice
    prior to the close of business on the Business Day immediately preceding the
    Payment Date;



        (6) that holders will be entitled to withdraw their election if the
    Paying Agent receives, not later than the close of business on the third
    Business Day immediately preceding the Payment Date, a telegram, facsimile
    transmission or letter setting forth the name of such holder, the principal
    amount of notes delivered for purchase and a statement that such holder is
    withdrawing his election to have such notes purchased; and



        (7) that holders whose notes are being purchased only in part will be
    issued new notes equal in principal amount to the unpurchased portion of the
    notes surrendered; PROVIDED that each note purchased and each new note
    issued shall be in a principal amount of $1,000 or an integral multiple
    thereof, with respect to the dollar notes, and [Euro]1,000 or an integral
    multiple thereof, with respect to the Euro notes.



    On the Payment Date, Carrier1 International shall



        (1) accept for payment on a pro rata basis notes or portions thereof
    tendered pursuant to an Offer to Purchase;



        (2) deposit with the relevant Paying Agent money sufficient to pay the
    purchase price of all notes or portions thereof so accepted; and


                                      105
<PAGE>

        (3) deliver, or cause to be delivered, to the relevant trustee all notes
    or portions thereof so accepted together with an Officers' Certificate
    specifying the notes or portions thereof accepted for payment by Carrier1
    International.



The relevant Paying Agent shall promptly mail to the holders of notes so
accepted payment in an amount equal to the purchase price, and the relevant
trustee shall promptly authenticate and mail to such holders a new note equal in
principal amount to any unpurchased portion of the note surrendered; PROVIDED
that each note purchased and each new note issued shall be in a principal amount
of $1,000 or an integral multiple thereof, with respect to the dollar notes, and
[Euro]1,000 or an integral multiple thereof, with respect to the Euro notes.
Carrier1 International will publicly announce the results of an Offer to
Purchase as soon as practicable after the Payment Date. The relevant trustee
shall act as the Paying Agent for an Offer to Purchase. Carrier1 International
will comply with Rule 14e-1 under the Exchange Act and any other securities laws
and regulations thereunder to the extent such laws and regulations are
applicable, in the event that Carrier1 International is required to repurchase
notes pursuant to an Offer to Purchase. To the extent the provisions of any such
laws or regulations conflict with the provisions of the relevant indenture,
Carrier1 International will comply with such laws and regulations and will not
be deemed to have breached its obligations under such indenture by virtue
thereof.



    "Permanent Guarantor" means a Restricted Subsidiary that irrevocably
guarantees the payment of the notes on an unsubordinated basis; provided that
such guarantee may provide that it shall be automatically and unconditionally
released and discharged upon:



        (1) any sale, exchange or transfer (including by way of merger or
    consolidation), to any Person not an Affiliate of Carrier1 International, of
    all of Carrier1 International's and each Restricted Subsidiary's Capital
    Stock in, or all or substantially all the assets of, such Restricted
    Subsidiary (which sale, exchange, transfer or other transaction is not
    prohibited by the relevant indenture),



        (2) the legal or covenant defeasance of the notes or satisfaction and
    discharge of the relevant indenture, subject to customary contingent
    reinstatement provisions or



        (3) upon the merger or consolidation of the Permanent Guarantor with and
    into Carrier1 International or another Permanent Guarantor that is the
    surviving Person in such merger or consolidation.


    "Permitted Holder" means any of the following: any of Providence Equity
Partners L.P., Providence Equity Partners II L.P., Providence Equity Partners
III L.P., Primus Capital Fund IV Limited Partnership and Primus Executive Fund
Limited Partnership and any of the respective Affiliates or successors of the
foregoing.

    "Permitted Investment" means:


        (1) an Investment in Carrier1 International (including the notes of
    either series) or a Restricted Subsidiary or a Person which will, upon the
    making of such Investment, become a Restricted Subsidiary or be merged or
    consolidated with or into, or transfer or convey all or substantially all
    its assets to, Carrier1 International or a Restricted Subsidiary; PROVIDED
    that such Person's primary business is related, ancillary or complementary
    to the businesses of Carrier1 International and its Restricted Subsidiaries
    on the date of such Investment;



        (2) Temporary Cash Investments;



        (3) commissions, payroll, travel and similar advances to cover matters
    that are expected at the time of such advances ultimately to be treated as
    expenses in accordance with GAAP;



        (4) stock, obligations, securities or other Investments received (a) in
    satisfaction of judgments or (b) in settlement of debts, or as a result of
    foreclosure, perfection or enforcement of any Lien, in each


                                      106
<PAGE>
    case under this clause (b) arising in the ordinary course of business and
    not in contemplation of the acquisition of such stock, obligations,
    securities or other Investments;


        (5) Investments in negotiable instruments held for collection, lease,
    utility and worker's compensation, performance and other similar pledges or
    deposits and other pledges or deposits permitted under the "Limitation on
    Liens" covenant;



        (6) obligations under Interest Rate Agreements and Currency Agreements
    designed solely to protect Carrier1 International or its Restricted
    Subsidiaries against fluctuations in interest rates or foreign currency
    exchange rates;



        (7) Investments in a joint venture to cover Carrier1 International's
    portion of the cost (including the cost of design, development, acquisition,
    construction, installation and improvement) of building a telecommunications
    network (or network segment) in Europe, provided that Carrier1 International
    or any of its Restricted Subsidiaries will directly own their portion of
    such network (or network segment); and Investments in joint ventures to
    acquire or maintain or otherwise relating to any rights-of-way, wayleaves,
    governmental approvals, licenses, franchises or concessions relating to any
    such network (or network segment);



        (8) Investments in any Person in an aggregate amount not to exceed 25%
    of any gains (net of any losses) attributable to Asset Sales after the
    Closing Date and prior to the date of such Investment; and



        (9) loans or advances to directors, officers or employees of Carrier1
    International or any Restricted Subsidiary that do not in the aggregate
    exceed $3 million at any time outstanding.



    "Permitted Joint Venture" means any joint venture between Carrier1
International or any Restricted Subsidiary and any Person other than a
Subsidiary, engaged in the provision or sale of telecommunications services, or
in any other business that is related, ancillary or complementary to the
provision or sale of telecommunications services, as determined in good faith by
the Board of Directors (whose determination shall be conclusive if evidenced by
a Board Resolution); PROVIDED that prior to making any Investment in such a
Person, Carrier1 International's Board of Directors shall have determined that
such Investment fits Carrier1 International's strategic plan and is on terms
that are fair and reasonable to Carrier1 International.


    "Permitted Liens" means:


        (1) Liens for taxes, assessments, governmental charges or claims not yet
    delinquent, or that in the aggregate are not material, or that are being
    contested in good faith by appropriate proceedings promptly instituted and
    diligently conducted and for which a reserve or other appropriate provision,
    if any, as shall be required in conformity with GAAP shall have been made;



        (2) statutory and common law Liens of landlords, carriers, warehousemen,
    mechanics, suppliers, materialmen or repairmen or other similar Liens
    arising in the ordinary course of business and with respect to amounts not
    yet delinquent or that have been bonded or being contested in good faith by
    appropriate proceedings promptly instituted and diligently conducted and for
    which a reserve or other appropriate provision, if any, as shall be required
    in conformity with GAAP shall have been made;



        (3) Liens incurred or deposits made in the ordinary course of business
    in connection with workers' compensation, unemployment insurance and other
    types of social security and other similar legislation or other
    insurance-related obligations (including, without limitation, pledges or
    deposits securing liability to insurance carriers under insurance or
    self-insurance arrangements);



        (4) Liens incurred or deposits made to secure the performance of
    tenders, bids, leases, licenses, obligations for utilities, statutory or
    regulatory obligations, bankers' acceptances, letters of credit, surety and
    appeal bonds, government or other contracts, completion guarantees,
    performance and


                                      107
<PAGE>
    return-of-money bonds and other obligations of a similar nature incurred in
    the ordinary course of business (exclusive of obligations for the payment of
    borrowed money);


        (5) easements, rights-of-way, municipal and zoning ordinances, utility
    agreements, reservations, encroachments, restrictions and similar charges,
    encumbrances, title defects or other irregularities that do not materially
    interfere with the ordinary course of business of Carrier1 International or
    any of its Restricted Subsidiaries;



        (6) Liens (including extensions, renewals and replacements thereof) upon
    real or personal property or assets (including leases on an indefeasible
    right-to-use basis); PROVIDED that


           (a) such Lien is created solely for the purpose of securing
       Indebtedness Incurred, in accordance with the "Limitation on
       Indebtedness" covenant described below, to finance or refinance the cost
       (including the cost of design, development, acquisition, construction,
       installation, improvement, transportation or integration) of the item of
       property or assets subject thereto and the original such Lien is created
       prior to, at the time of or within one year after the later of the
       acquisition, the completion of construction or the commencement of full
       operation of such property or assets,

           (b) the principal amount of the Indebtedness secured by such Lien
       does not exceed 100% of such cost and

           (c) any such Lien shall not extend to or cover any property or assets
       other than such item of property or assets and any improvements,
       accessions or proceeds in respect of such item;


        (7) leases, subleases, licenses or sublicenses granted to others that do
    not materially interfere with the ordinary course of business of Carrier1
    International and its Restricted Subsidiaries, taken as a whole;



        (8) Liens encumbering property or assets under construction (and related
    rights) in favor of a contractor or developer, or arising from progress or
    partial payments by a customer of Carrier1 International or its Restricted
    Subsidiaries relating to such property or assets;



        (9) any interest or title of a lessor in the property subject to any
    Capitalized Lease or operating lease;



        (10) Liens arising from filing Uniform Commercial Code financing
    statements regarding leases;



        (11) Liens (including extensions, renewals and replacements thereof) on
    property or assets of, or on shares of Capital Stock or Indebtedness of, any
    Person existing (in the case of the original such Lien) at the time such
    Person becomes, or becomes a part of, any Restricted Subsidiary; PROVIDED
    that such Liens do not extend to or cover any property or assets of Carrier1
    International or any Restricted Subsidiary other than the property, assets,
    Capital Stock or Indebtedness so acquired (plus improvements, accessions or
    proceeds (including dividends or distributions) in respect thereof);



        (12) Liens in favor of Carrier1 International or any Restricted
    Subsidiary;



        (13) Liens arising from the rendering of a final judgment, order, decree
    or award against Carrier1 International or any Restricted Subsidiary that
    does not give rise to an Event of Default;



        (14) Liens securing reimbursement obligations with respect to letters of
    credit that encumber documents and other property relating to such letters
    of credit and the products and proceeds thereof;



        (15) Liens in favor of customs and revenue authorities arising as a
    matter of law to secure payment of customs duties in connection with the
    importation of goods;



        (16) Liens encumbering customary initial deposits and margin deposits,
    and other Liens that are within the general parameters customary in the
    industry and incurred in the ordinary course of


                                      108
<PAGE>

    business, in each case, securing Indebtedness or other obligations under
    Interest Rate Agreements and Currency Agreements and forward contracts,
    options, future contracts, futures options or similar agreements or
    arrangements designed solely to protect Carrier1 International or any of its
    Restricted Subsidiaries from fluctuations in interest rates, currencies or
    the price of commodities;



        (17) Liens arising out of conditional sale, title retention, consignment
    or similar arrangements for the sale of goods entered into by Carrier1
    International or any of its Restricted Subsidiaries in the ordinary course
    of business;



        (18) Liens on or sales or transfers of receivables (including related
    rights);



        (19) Liens that secure Indebtedness or other obligations with an
    aggregate principal amount not in excess of $5 million at any time
    outstanding;



        (20) Liens placed by any third party on property over which Carrier1
    International or any Restricted Subsidiary has easement or other rights or
    on any leased property, or arising by reason of subordination or similar
    agreements relating thereto; and Liens arising by reason of any condemnation
    or eminent domain proceedings;



        (21) Liens on Capital Stock or other securities of an Unrestricted
    Subsidiary that secure Indebtedness or other obligations of such
    Unrestricted Subsidiary;



        (22) any encumbrance or restriction (including, but not limited to, put
    and call agreements) with respect to Capital Stock of any joint venture or
    similar arrangement pursuant to any joint venture or similar agreement;



        (23) Liens (including extensions, renewals and replacements thereof) on
    property or assets acquired by Carrier1 International or any Restricted
    Subsidiary; provided that


           (a) such Liens were not created in connection with or in anticipation
       of such acquisition,

           (b) such Liens do not secure Indebtedness other than Indebtedness
       assumed in connection with such acquisition, and


           (c) such Liens do not extend to or cover any property or assets of
       Carrier1 International or any Restricted Subsidiary other than the
       property or assets so acquired (plus improvements, accessions or proceeds
       in respect thereof); and



        (24) Liens on cash set aside at the time of the Incurrence of any
    Indebtedness, or government securities purchased with such cash, in either
    case to the extent that such cash or government securities prefund the
    payment of interest on such Indebtedness and are held in an escrow account
    or similar arrangement to be applied for such purpose.



    "Pledge Account" means an account established with the relevant Securities
Intermediary for the benefit of the applicable trustee pursuant to the terms of
relevant Pledge Agreement for the deposit of the applicable Pledged Securities
to be purchased by Carrier1 International with the net proceeds from the sale of
relevant series of notes.



    "Pledge Agreements" means the U.S. Dollar Collateral Pledge and Security
Agreement, dated as of the Closing Date, made by Carrier1 International in favor
of the relevant trustee with respect to the dollar notes and the Euro Collateral
Pledge and Security Agreement, dated as of the Closing Date, made by Carrier1
International in favor of the relevant trustee with respect to the Euro notes,
as each such agreement may be amended, restated, supplemented or otherwise
modified from time to time.



    "Pledged Securities" means the U.S. Government Securities to be purchased by
Carrier1 International and held in the relevant Pledge Account in accordance
with the Pledge Agreement related to the dollar notes and the European
Government Securities to be purchased by Carrier1 International and held in the
relevant Pledge Account in accordance with the Pledge Agreement related to the
Euro notes.


                                      109
<PAGE>
    "Preferred Stock" means, with respect to any Person, any and all shares,
interests, participations or other equivalents (however designated, whether
voting or non-voting) of such Person's preferred or preference equity, whether
now outstanding or issued after the Closing Date, including, without limitation,
all series and classes of such preferred stock or preference stock.

    "refinance" means refinance, refund, replace, renew, repay, modify, restate,
defer, substitute, supplement, reissue, resell or extend (including by way of
any exchange of Indebtedness, or pursuant to any defeasance or discharge
mechanism); and the terms "refinances," "refinanced" and "refinancing" as used
for any purpose in the Indentures shall have a correlative meaning.

    "Released Indebtedness" means, with respect to any Asset Sale:


        (1) Indebtedness of Carrier1 International or any Restricted Subsidiary
    which is assumed by the purchaser or any affiliate thereof in connection
    with such Asset Sale; PROVIDED that Carrier1 International or such
    Restricted Subsidiary receives written, unconditional, valid and enforceable
    releases from each creditor, no later than the closing date of such Asset
    Sale and



        (2) Indebtedness of a Restricted Subsidiary that is no longer a
    Restricted Subsidiary as a result of such Asset Sale; PROVIDED that neither
    Carrier1 International nor any other Restricted Subsidiary thereafter
    Guarantees such Indebtedness.



    "Restricted Subsidiary" means any Subsidiary of Carrier1 International other
than an Unrestricted Subsidiary.


    "S&P" means Standard & Poor's Ratings Services, a division of the
McGraw-Hill Companies, and its successors.

    "Significant Subsidiary" means, at any date of determination, any Restricted
Subsidiary that, together with its Subsidiaries:


        (1) for the most recent fiscal year of Carrier1 International, accounted
    for more than 10% of the consolidated revenues of Carrier1 International and
    its Restricted Subsidiaries or



        (2) as of the end of such fiscal year, was the owner of more than 10% of
    the consolidated assets of Carrier1 International and its Restricted
    Subsidiaries,



all as set forth on the most recently available consolidated financial
statements of Carrier1 International for such fiscal year.


    "Stated Maturity" means:


        (1) with respect to any debt security, the date specified in such debt
    security as the fixed date on which the final installment of principal of
    such debt security is due and payable and



        (2) with respect to any scheduled installment of principal of or
    interest on any debt security, the date specified in such debt security as
    the fixed date on which such installment is due and payable.



    "Strategic Subordinated Indebtedness" means Indebtedness of Carrier1
International or any Permanent Guarantor Incurred to finance the acquisition of
a Person engaged in a business that is related, ancillary or complementary to
the business conducted by Carrier1 International or any of its Restricted
Subsidiaries, which Indebtedness by its terms, or by the terms of any agreement
or instrument pursuant to which such Indebtedness is Incurred:



        (1) is expressly made subordinate in right of payment to the notes and



        (2) provides that no payment of principal, premium or interest on, or
    any other payment with respect to, such Indebtedness may be made prior to
    the payment in full of all of Carrier1 International's obligations under the
    notes;



PROVIDED that such Indebtedness may provide for and be repaid at any time from
the proceeds of a capital contribution or the sale of Capital Stock (other than
Disqualified Stock) of Carrier1 International after the Incurrence of such
Indebtedness.


                                      110
<PAGE>
    "Subsidiary" means, with respect to any Person, any corporation, association
or other business entity of which more than 50% of the voting power of the
outstanding Voting Stock is owned, directly or indirectly, by such Person and
one or more other Subsidiaries of such Person.

    "Temporary Cash Investment" means any of the following:


        (1) direct obligations of the United States of America or any agency
    thereof or obligations fully and unconditionally guaranteed by the United
    States of America or any agency thereof;



        (2) bankers' acceptances, time deposit accounts, certificates of deposit
    and money market deposits maturing within one year of the date of
    acquisition thereof issued by a bank or trust company which is organized
    under the laws of the United States of America, any state thereof or any
    foreign country recognized by the United States of America, and which bank
    or trust company has capital, surplus and undivided profits aggregating in
    excess of $50 million (or the foreign currency equivalent thereof) and has
    outstanding debt which is rated "A" (or such similar equivalent rating) or
    higher by at least one nationally recognized statistical rating organization
    (as defined in Rule 436 under the Securities Act) or any money-market fund
    sponsored by a registered broker dealer or mutual fund distributor;



        (3) repurchase obligations with a term of not more than 30 days for
    underlying securities of the types described in clause (1) above or clause
    (6) below entered into with a bank meeting the qualifications described in
    clause (2) above;



        (4) commercial paper, maturing not more than one year after the date of
    acquisition, issued by a corporation (other than an Affiliate of Carrier1
    International) organized and in existence under the laws of the United
    States of America, any state thereof or any foreign country recognized by
    the United States of America with a rating at the time as of which any
    investment therein is made of "P-1" (or higher) according to Moody's or
    "A-1" (or higher) according to S&P;



        (5) securities with maturities of six months or less from the date of
    acquisition issued or fully and unconditionally guaranteed by any state,
    commonwealth or territory of the United States of America, or by any
    political subdivision or taxing authority thereof, and rated at least "A" by
    S&P or Moody's; and



        (6) direct obligations of, or obligations fully and unconditionally
    guaranteed by, (a) The Netherlands, the United Kingdom, France, Germany or
    Switzerland, or (b) any other member of the European Economic Community and
    rated at least "A" by S&P or Moody's.


    "Trade Payables" means, with respect to any Person, any accounts payable or
any other indebtedness or monetary obligation to trade creditors created,
assumed or guaranteed by such Person or any of its Subsidiaries arising in the
ordinary course of business in connection with the acquisition of goods or
services.


    "Transaction Date" means, with respect to the Incurrence of any Indebtedness
by Carrier1 International or any of its Restricted Subsidiaries, the date such
Indebtedness is to be Incurred and, with respect to any Restricted Payment, the
date such Restricted Payment is to be made.


    "Unrestricted Subsidiary" means:


        (1) any Subsidiary of Carrier1 International that at the time of
    determination shall be designated an Unrestricted Subsidiary by the Board of
    Directors in the manner provided below and



        (2) any Subsidiary of an Unrestricted Subsidiary.



The Board of Directors may designate any Restricted Subsidiary (including any
newly acquired or newly formed Subsidiary of Carrier1 International) to be an
Unrestricted Subsidiary unless such Subsidiary owns


                                      111
<PAGE>

any Capital Stock of, or owns or holds any Lien on any property of, Carrier1
International or any Restricted Subsidiary; PROVIDED that:



        (A) any Guarantee by Carrier1 International or any Restricted Subsidiary
    of any Indebtedness of the Subsidiary being so designated shall be deemed an
    "Incurrence" of such Indebtedness and an "Investment" by Carrier1
    International or such Restricted Subsidiary (or both, if applicable) at the
    time of such designation;



        (B) either (1) the Subsidiary to be so designated has total assets of
    $1,000 or less or (2) if such Subsidiary has assets greater than such
    amount, such designation would be permitted under the "Limitation on
    Restricted Payments" covenant described below and


        (C) if applicable, the Incurrence of Indebtedness and the Investment
    referred to in clause (A) of this proviso would be permitted under the
    "Limitation on Indebtedness" and "Limitation on Restricted Payments"
    covenants described below.

The Board of Directors may designate any Unrestricted Subsidiary to be a
Restricted Subsidiary; PROVIDED that:


        (1) no Default or Event of Default shall have occurred and be continuing
    at the time of or after giving effect to such designation and



        (2) all Liens and Indebtedness of such Unrestricted Subsidiary
    outstanding immediately after such designation would, if Incurred at such
    time, have been permitted to be Incurred (and shall be deemed to have been
    Incurred) for all purposes of the relevant indenture.



Any such designation by the Board of Directors shall be evidenced to the
relevant trustee by promptly filing with the trustee a copy of the Board
Resolution giving effect to such designation and an Officers' Certificate
certifying that such designation complied with the foregoing provisions.


    "U.S. Government Obligations" means securities that are:


        (1) direct obligations of the United States of America for the payment
    of which its full faith and credit is pledged or



        (2) obligations of a Person controlled or supervised by and acting as an
    agency or instrumentality of the United States of America the payment of
    which is unconditionally guaranteed as a full faith and credit obligation by
    the United States of America,



which, in either case, are not callable or redeemable at the option of the
issuer thereof at any time prior to the Stated Maturity of the notes, and shall
also include a depository receipt issued by a bank or trust company as custodian
with respect to any such U.S. Government Obligation or a specific payment of
interest on or principal of any such U.S. Government Obligation held by such
custodian for the account of the holder of a depository receipt; PROVIDED that
(except as required by law) such custodian is not authorized to make any
deduction from the amount payable to the holder of such depository receipt from
any amount received by the custodian in respect of the U.S. Government
Obligation or the specific payment of interest on or principal of the U.S.
Government Obligation evidenced by such depository receipt.


    "U.S. Government Securities" means direct obligations of, obligations fully
guaranteed by, or participations in pools consisting solely of obligations of or
obligations guaranteed by, the United States of America for the payment of which
guarantee or obligations the full faith and credit of the United States of
America is pledged and which are not callable or redeemable at the option of the
issuer thereof.

    "Voting Stock" means with respect to any Person, Capital Stock of any class
or kind ordinarily having the power to vote for the election of directors,
managers or other voting members of the governing body of such Person.

                                      112
<PAGE>
    "Wholly Owned" means, with respect to any Subsidiary of any Person, the
ownership of all of the outstanding Capital Stock of such Subsidiary (other than
any director's qualifying shares or Investments by foreign nationals mandated by
applicable law) by such Person or one or more Wholly Owned Subsidiaries of such
Person.

COVENANTS

    LIMITATION ON INDEBTEDNESS


    (a)  Carrier1 International will not, and will not permit any of its
Restricted Subsidiaries to, Incur any Indebtedness (other than the notes of
either series (including any new notes of either series, but excluding any
Additional Notes), and other Indebtedness existing on the Closing Date);
PROVIDED that Carrier1 International or any Permanent Guarantor may Incur
Indebtedness if, after giving effect to the Incurrence of such Indebtedness and
the receipt and application of the proceeds therefrom, the Consolidated Leverage
Ratio would be greater than zero and less than 6:1.



    Notwithstanding the foregoing, Carrier1 International and any Restricted
Subsidiary (except as specified below) may Incur each and all of the following:



        (1) Indebtedness outstanding at any time in an aggregate principal
    amount not to exceed (after giving effect to any refinancing thereof) the
    sum of


           (a) $100 million, less any amount of such Indebtedness permanently
       repaid as provided under the "Limitation on Asset Sales" covenant
       described below, plus


           (b) an amount equal to the lesser of (1) 80% of the consolidated book
       value of the accounts receivable of Carrier1 International and its
       Restricted Subsidiaries determined in accordance with GAAP (determined as
       of the end of the most recently ended fiscal quarter for which reports
       have been filed with the Commission or provided to the relevant trustee)
       and (2) $100 million;



        (2) Indebtedness owed (A) to Carrier1 International evidenced by a
    promissory note or (B) to any Restricted Subsidiary; PROVIDED that any event
    which results in any such Restricted Subsidiary ceasing to be a Restricted
    Subsidiary or any subsequent transfer of such Indebtedness (other than to
    Carrier1 International or another Restricted Subsidiary) shall be deemed, in
    each case, to constitute an Incurrence of such Indebtedness not permitted by
    this clause (2);



        (3) Indebtedness issued to refinance then outstanding Indebtedness
    (other than Indebtedness Incurred under clause (1), (2), (4), (6), (8), (11)
    or (12) of this paragraph) and any refinancings thereof, in an amount not to
    exceed the amount so refinanced (plus premiums, accrued interest, fees and
    expenses); PROVIDED that Indebtedness the proceeds of which are used to
    refinance the notes in part or Indebtedness that is PARI PASSU with, or
    expressly subordinated in right of payment to, the notes or any notes
    Guarantee shall only be permitted under this clause (3) if



           (A) in case the notes are refinanced in part or the Indebtedness to
       be refinanced is PARI PASSU with the notes or any notes Guarantee, such
       new Indebtedness, by its terms or by the terms of any agreement or
       instrument pursuant to which such new Indebtedness is outstanding, is
       expressly made PARI PASSU with, or expressly subordinate in right of
       payment to, the remaining notes or any notes Guarantee,



           (B) in case the Indebtedness to be refinanced is expressly
       subordinated in right of payment to the notes or any notes Guarantee,
       such new Indebtedness, by its terms or by the terms of any agreement or
       instrument pursuant to which such new Indebtedness is issued or remains
       outstanding, is expressly made subordinate in right of payment to the
       notes or any notes Guarantee at least to the extent that the Indebtedness
       to be refinanced is subordinated to the notes or any notes Guarantee and


                                      113
<PAGE>

           (C) such new Indebtedness, determined as of the date of Incurrence of
       such new Indebtedness, does not mature prior to the Stated Maturity of
       the Indebtedness to be refinanced and the Average Life of such new
       Indebtedness is at least equal to the remaining Average Life of the
       Indebtedness to be refinanced;



    and PROVIDED FURTHER that in no event may Indebtedness of Carrier1
    International be refinanced by means of any Indebtedness of any Restricted
    Subsidiary pursuant to this clause (3);



        (4) Indebtedness (A) in respect of performance, surety, appeal or other
    similar bonds provided in the ordinary course of business and (B) arising
    from agreements providing for indemnification, adjustment of purchase price
    or similar obligations, or from Guarantees or letters of credit, bankers'
    acceptances, surety or performance bonds or other similar instruments
    securing any obligations of Carrier1 International or any of its Restricted
    Subsidiaries pursuant to such agreements, in any case Incurred in connection
    with the disposition of any business, assets or Restricted Subsidiary (other
    than Guarantees of Indebtedness Incurred by any Person acquiring all or any
    portion of such business, assets or Restricted Subsidiary for the purpose of
    financing such acquisition), in a principal amount not to exceed the gross
    proceeds actually received by Carrier1 International or any Restricted
    Subsidiary in connection with such disposition;



        (5) Indebtedness of Carrier1 International or any Permanent Guarantor,
    to the extent the net proceeds thereof are promptly (A) used to purchase
    notes tendered in an Offer to Purchase made as a result of a Change in
    Control or (B) deposited to defease the notes as described below under
    "Defeasance";



        (6) Guarantees of the notes and Guarantees of Indebtedness of Carrier1
    International by any Restricted Subsidiary provided the Guarantee of such
    Indebtedness is permitted by and made in accordance with the "Limitation on
    Issuance of Guarantees by Restricted Subsidiaries" covenant described below;
    and Guarantees of Indebtedness of any Restricted Subsidiary by any
    Restricted Subsidiary provided such Restricted Subsidiary simultaneously
    executes and delivers a supplemental indenture to the relevant indenture
    providing for a Guarantee of payment of the notes by such Restricted
    Subsidiary;



        (7) Indebtedness (including Guarantees and the German Network L/C)
    Incurred to finance or refinance the cost (including the cost of design,
    development, acquisition, construction, installation, improvement,
    transportation or integration) to acquire equipment, inventory or network
    assets (including leases on an indefeasible right-to-use basis and multiple
    investment units) (including acquisitions by way of Capitalized Lease and
    acquisitions of the Capital Stock of a Person that becomes a Restricted
    Subsidiary to the extent of the fair market value of the equipment,
    inventory or network assets so acquired) by Carrier1 International or a
    Restricted Subsidiary;



        (8) Indebtedness of Carrier1 International or any Permanent Guarantor
    not to exceed, at any one time outstanding (after giving effect to any
    refinancing thereof), two times the sum of



           (A) the Net Cash Proceeds received by Carrier1 International after
       the Closing Date as a capital contribution or from the issuance and sale
       of its Capital Stock (other than Disqualified Stock) to a Person that is
       not a Subsidiary of Carrier1 International, to the extent (I) such
       capital contribution or Net Cash Proceeds have not been used pursuant to
       clause (C)(2) of the first paragraph or clause (3), (4), (6) or (10) of
       the second paragraph of the "Limitation on Restricted Payments" covenant
       described below to make a Restricted Payment and (II) if such capital
       contribution or Net Cash Proceeds are used to consummate a transaction
       pursuant to which Carrier1 International Incurs Acquired Indebtedness,
       the amount of such Net Cash Proceeds exceeds one-half of the amount of
       Acquired Indebtedness so Incurred and



           (B) 80% of the fair market value of property (other than cash and
       cash equivalents) received by Carrier1 International after the Closing
       Date as a capital contribution or from the sale of its


                                      114
<PAGE>

       Capital Stock (other than Disqualified Stock) to a Person that is not a
       Subsidiary of Carrier1 International, to the extent (I) such capital
       contribution or sale of Capital Stock has not been used pursuant to
       clause (3), (4) or (7) of the second paragraph of the "Limitation on
       Restricted Payments" covenant described below to make a Restricted
       Payment and (II) if such capital contribution or Capital Stock is used to
       consummate a transaction pursuant to which Carrier1 International Incurs
       Acquired Indebtedness, 80% of the fair market value of the property
       received exceeds one-half of the amount of Acquired Indebtedness so
       Incurred PROVIDED that such Indebtedness does not mature prior to the
       Stated Maturity of the notes and has an Average Life longer than the
       notes;



        (9) Acquired Indebtedness;



        (10) Strategic Subordinated Indebtedness;



        (11) Indebtedness in respect of bankers' acceptance and letters of
    credit, all in the ordinary course of business, in an aggregate amount
    outstanding at any time not to exceed $10 million; and



        (12) subordinated Indebtedness of Carrier1 International or any
    Permanent Guarantor (in addition to Indebtedness permitted under clauses (1)
    through (11) above) in an aggregate principal amount outstanding at any time
    (after giving effect to any refinancing thereof) not to exceed $100 million.



    (b)  For purposes of determining compliance with any dollar-denominated
restriction on the Incurrence of Indebtedness denominated in another currency,
the dollar-equivalent principal amount of such Indebtedness Incurred pursuant
thereto shall be calculated based on the relevant currency exchange rate in
effect on the date that such Indebtedness was Incurred (or, in the case of
Indebtedness under a revolving credit facility, at the time of commitment),
PROVIDED that if such Indebtedness is Incurred to refinance other Indebtedness
denominated in a foreign currency, and such refinancing would cause the
applicable dollar-denominated restriction to be exceeded if calculated at the
relevant currency exchange rate in effect on the date of such refinancing, such
dollar-denominated restriction shall be deemed not to have been exceeded so long
as the principal amount of such refinancing Indebtedness does not exceed the
principal amount of such Indebtedness being refinanced. The principal amount of
any Indebtedness Incurred to refinance other Indebtedness, if Incurred in a
different currency from the Indebtedness being refinanced, shall be calculated
based on the currency exchange rate applicable to the currencies in which such
respective Indebtedness is denominated that is in effect on the date of such
refinancing.


    (c)  For purposes of determining any particular amount of Indebtedness under
this "Limitation on Indebtedness" covenant,

        (1) Guarantees, Liens or obligations with respect to letters of credit,
    bankers' acceptances or other similar instruments supporting Indebtedness
    otherwise included in the determination of such particular amount shall not
    be included and

        (2) any Liens granted pursuant to the equal and ratable provisions
    referred to in the "Limitation on Liens" covenant described below shall not
    be treated as giving rise to Indebtedness.

For purposes of determining compliance with this "Limitation on Indebtedness"
covenant,

        (1) any other obligation of the obligor on such Indebtedness arising
    under any Lien or letter of credit, bankers' acceptance or other similar
    instrument or obligation supporting such Indebtedness shall be disregarded
    to the extend that the same secures the principal amount of such
    Indebtedness and


        (2) in the event that an item of Indebtedness meets the criteria of more
    than one of the types of Indebtedness described in the above clauses,
    Carrier1 International, in its sole discretion, shall classify, and from
    time to time may reclassify, such item of Indebtedness and only be required
    to


                                      115
<PAGE>
    include the amount and type of such Indebtedness in one of such clauses (but
    may allocate portions of such Indebtedness between or among such clauses).

    LIMITATION ON RESTRICTED PAYMENTS


    Carrier1 International will not, and will not permit any Restricted
Subsidiary to, directly or indirectly:



        (1) declare or pay any dividend or make any distribution on or with
    respect to its Capital Stock (other than (x) dividends or distributions
    payable solely in shares of its Capital Stock (other than Disqualified
    Stock) or in options, warrants or other rights to acquire shares of such
    Capital Stock and (y) dividends or distributions on Capital Stock of a
    Restricted Subsidiary held by minority interest holders on no more than a
    pro rata basis, measured by value and based on all outstanding Capital Stock
    of such Restricted Subsidiary) held by Persons other than Carrier1
    International or any of its Restricted Subsidiaries,



        (2) purchase, redeem, retire or otherwise acquire for value any shares
    of Capital Stock of



           (A) Carrier1 International or an Unrestricted Subsidiary (including
       options, warrants or other rights to acquire such shares of Capital
       Stock) held by any Person other than Carrier1 International or any Wholly
       Owned Restricted Subsidiary or



           (B) a Restricted Subsidiary (including options, warrants or other
       rights to acquire such shares of Capital Stock) held by any Affiliate of
       Carrier1 International (other than a Wholly Owned Restricted Subsidiary)
       or any holder (or any Affiliate of such holder) of 5% or more of the
       Capital Stock of Carrier1 International,



        (3) make any voluntary or optional principal payment, or voluntary or
    optional redemption, repurchase, defeasance, or other acquisition or
    retirement for value, of Indebtedness of Carrier1 International that is
    expressly subordinated in right of payment to the Notes or any Notes
    Guarantee or



        (4) make any Investment, other than a Permitted Investment, in any other
    Person



(such payments or any other actions described in clauses (1) through (4) above
being collectively "Restricted Payments") if, at the time of, and after giving
effect to, the proposed Restricted Payment:


        (A) a Default or Event of Default shall have occurred and be continuing,


        (B) Carrier1 International could not Incur at least $1.00 of
    Indebtedness under the first paragraph of the "Limitation on Indebtedness"
    covenant or


        (C) the aggregate amount of all Restricted Payments (the amount, if
    other than in cash, to be determined in good faith by the Board of
    Directors, whose determination shall be conclusive and evidenced by a Board
    Resolution) made after the Closing Date shall exceed the sum of


           (1) 50% of the aggregate amount of the Adjusted Consolidated Net
       Income (or, if the Adjusted Consolidated Net Income is a loss, minus 100%
       of the amount of such loss) accrued on a cumulative basis during the
       period (taken as one accounting period) beginning on the first day of the
       fiscal quarter beginning immediately following the Closing Date and
       ending on the last day of the last fiscal quarter preceding the
       Transaction Date for which reports have been filed with the Commission or
       provided to the relevant trustee pursuant to the "Commission Reports and
       Reports to Holders" covenant PLUS



           (2) the aggregate Net Cash Proceeds received by Carrier1
       International after the Closing Date as a capital contribution or from
       the issuance and sale permitted by the relevant indenture of its Capital
       Stock (other than Disqualified Stock) to a Person who is not a Subsidiary
       of Carrier1 International, including the proceeds of an issuance or sale
       permitted by the relevant


                                      116
<PAGE>

       indenture of Indebtedness of Carrier1 International for cash subsequent
       to the Closing Date upon the conversion of such Indebtedness into Capital
       Stock (other than Disqualified Stock) of Carrier1 International, or from
       the issuance to a Person who is not a Subsidiary of Carrier1
       International of any options, warrants or other rights to acquire Capital
       Stock of Carrier1 International (in each case, exclusive of any
       Disqualified Stock or any options, warrants or other rights that are
       redeemable at the option of the holder, or are required to be redeemed,
       prior to the Stated Maturity of the notes), in each case except to the
       extent such Net Cash Proceeds are used to Incur Indebtedness pursuant to
       clause (8) of the second paragraph under the "Limitation on Indebtedness"
       covenant PLUS



           (3) an amount equal to the net reduction in Investments (other than
       reductions in Permitted Investments and Investments under clause (6), (8)
       or (12) of the second paragraph of this "Limitation on Restricted
       Payments" covenant) in any Person resulting from payments of interest on
       Indebtedness, dividends, distributions, repayments of loans or advances,
       or other transfers of assets, in each case to Carrier1 International or
       any Restricted Subsidiary or from the Net Cash Proceeds from the sale or
       other disposition of any such Investment (except, in each case, to the
       extent of any gain on such sale or other disposition that would be
       included in the calculation of Adjusted Consolidated Net Income for
       purposes of clause (C)(1) above), or from redesignations of Unrestricted
       Subsidiaries as Restricted Subsidiaries (valued in each case as provided
       in the definition of "Investments"), not to exceed, in each case, the
       amount of Investments previously made by Carrier1 International or any
       Restricted Subsidiary in such Person or Unrestricted Subsidiary.


        The foregoing provision shall not be violated by reason of:


        (1) the payment of any dividend within 60 days after the date of
    declaration thereof if, at said date of declaration, such payment would
    comply with the foregoing paragraph;



        (2) the redemption, repurchase, defeasance or other acquisition or
    retirement for value of Indebtedness that is subordinated in right of
    payment to the notes or any notes Guarantee, including premium, if any, and
    accrued and unpaid interest, with the proceeds of, or in exchange for,
    Indebtedness Incurred under clause (3) of the second paragraph of the
    "Limitation on Indebtedness" covenant;



        (3) the repurchase, redemption or other acquisition of Capital Stock of
    Carrier1 International or any Subsidiary of Carrier1 International (or
    options, warrants or other rights to acquire such Capital Stock) in exchange
    for, or out of the proceeds of a capital contribution or a substantially
    concurrent offering of, shares of Capital Stock (other than Disqualified
    Stock) of Carrier1 International (or options, warrants or other rights to
    acquire such Capital Stock);



        (4) the making of any principal payment on or the repurchase,
    redemption, retirement, defeasance or other acquisition for value of
    Indebtedness of Carrier1 International which is subordinated in right of
    payment to the notes in exchange for, or out of the proceeds of a capital
    contribution or a substantially concurrent offering of, shares of the
    Capital Stock (other than Disqualified Stock) of Carrier1 International (or
    options, warrants or other rights to acquire such Capital Stock);



        (5) payments or distributions to dissenting shareholders pursuant to
    applicable law, pursuant to or in connection with a consolidation, merger or
    transfer of assets that complies with the provisions of the relevant
    indenture applicable to mergers, consolidations and transfers of all or
    substantially all of the property and assets of Carrier1 International;



        (6) any Investment in any Person the primary business of which is
    related, ancillary or complementary to the business of Carrier1
    International and its Restricted Subsidiaries on the date of


                                      117
<PAGE>

    such Investment; PROVIDED that the aggregate amount of Investments made
    pursuant to this clause (6) does not exceed the sum of


           (a) $25 million, plus


           (b) the amount of Net Cash Proceeds received by Carrier1
       International after the Closing Date as a capital contribution or from
       the sale of its Capital Stock (other than Disqualified Stock) to a Person
       who is not a Subsidiary of Carrier1 International, except to the extent
       such Net Cash Proceeds are used to Incur Indebtedness pursuant to clause
       (8) of the second paragraph under the "Limitation on Indebtedness"
       covenant or to make Restricted Payments pursuant to clause (C)(2) of the
       first paragraph, or clauses (3), (4) or (10) of this paragraph, of this
       "Limitation on Restricted Payments" covenant, plus



           (c) the net reduction in Investments made pursuant to this clause (6)
       resulting from distributions on or repayments of such Investments or from
       the Net Cash Proceeds from the sale or other disposition of any such
       Investment (except in each case to the extent of any gain on such sale or
       other disposition that would be included in the calculation of Adjusted
       Consolidated Net Income for purposes of clause (C)(1) above) or from such
       Person becoming a Restricted Subsidiary (valued in each case as provided
       in the definition of "Investments"),


    PROVIDED that the net reduction in any Investment shall not exceed the
amount of such Investment;


        (7) Investments acquired as a capital contribution to or in exchange for
    Capital Stock (other than Disqualified Stock) of Carrier1 International;



        (8) Investments in Permitted Joint Ventures not exceeding, at the time
    of the Investment, the sum of


           (A) $10 million and


           (B) the net reduction in Investments made pursuant to this clause (8)
       resulting from distributions on or repayments of such Investments or from
       the Net Cash Proceeds from the sale or other disposition of any such
       Investment (except in each case to the extent of any gain on such sale or
       disposition that would be included in the calculation of Adjusted
       Consolidated Net Income for purposes of clause (C)(1) above) or from such
       Person becoming a Restricted Subsidiary (valued in each case as provided
       in the definition of "Investments"), PROVIDED that the net reduction in
       any Investment shall not exceed the amount of such Investment;



        (9) repurchases of Warrants pursuant to a Repurchase Offer or within ten
    days of their expiration in accordance with the terms of the Warrant
    Agreements in effect on the Closing Date, any purchase of any fractional
    shares of Common Stock (or other Capital Stock of Carrier1 International
    issuable upon exercise of the Warrants) in connection with an exercise of
    the Warrants, and any payments in connection with the anti-dilution
    provisions of the Warrant Agreements;



        (10) the purchase, redemption, retirement or other acquisition for value
    of shares of Capital Stock of Carrier1 International or options, warrants or
    other rights to purchase such shares held by Management Investors upon
    death, disability, retirement, termination of employment or pursuant to the
    terms of any agreement under which such shares of Capital Stock or options,
    warrants or other rights were issued; PROVIDED that the aggregate
    consideration paid for such purchase, redemption, retirement or other
    acquisition for value of such shares or options, warrants or other rights
    after the Closing Date does not in the aggregate exceed


                                      118
<PAGE>
           (A) $5 million, plus


           (B) the aggregate Net Cash Proceeds received by Carrier1
       International after the Closing Date as a capital contribution from, or
       from the issuance or sale to, Management Investors of Capital Stock of
       Carrier1 International or any options, warrants or other rights to
       acquire such Capital Stock, plus


           (C) the proceeds of insurance policies used to effect any such
       purchase, redemption, retirement or other acquisition;


        (11) any purchase, redemption, retirement or other acquisition of
    Capital Stock deemed to occur upon the exercise of options, warrants or
    other rights if such Capital Stock represents a portion of the exercise
    price thereof; or



        (12) other Restricted Payments in an aggregate amount not to exceed $5
    million plus the net reduction in Investments made pursuant to this clause
    (12) resulting from distributions on or repayments of such Investments or
    from the Net Cash Proceeds from the sale or other disposition of any such
    Investment (except in each case to the extent of any gain on such sale or
    disposition that would be included in the calculation of Adjusted
    Consolidated Net Income for purposes of clause (C)(1) above) or from such
    Person becoming a Restricted Subsidiary (valued in each case as provided in
    the definition of "Investments"), PROVIDED that the net reduction in any
    Investment shall not exceed the amount of such Investment;



PROVIDED that, except in the case of clauses (1), (3) and (11), no Default or
Event of Default shall have occurred and be continuing or occur as a consequence
of the actions or payments set forth therein.



    Each Restricted Payment permitted pursuant to the preceding paragraph (other
than the Restricted Payment referred to in clause (2) thereof, an exchange of
Capital Stock for Capital Stock or Indebtedness referred to in clause (3) or (4)
thereof, an Investment referred to in clause (7) thereof and a purchase,
redemption, retirement or other acquisition of Capital Stock referred to in
clause (11) thereof), and the Net Cash Proceeds from any capital contribution or
any issuance of Capital Stock referred to in clauses (3), (4) and (6) thereof,
shall be included in calculating whether the conditions of clause (C) of the
first paragraph of this "Limitation on Restricted Payments" covenant have been
met with respect to any subsequent Restricted Payments.


    LIMITATION ON DIVIDEND AND OTHER PAYMENT RESTRICTIONS AFFECTING RESTRICTED
     SUBSIDIARIES


    Carrier1 International will not, and will not permit any Restricted
Subsidiary to, create or otherwise cause or suffer to exist or become effective
any consensual encumbrance or restriction of any kind on the ability of any
Restricted Subsidiary to:



        (1) pay dividends or make any other distributions permitted by
    applicable law on any Capital Stock of such Restricted Subsidiary owned by
    Carrier1 International or any other Restricted Subsidiary,



        (2) pay any Indebtedness owed to Carrier1 International or any other
    Restricted Subsidiary,



        (3) make loans or advances to Carrier1 International or any other
    Restricted Subsidiary, or



        (4) transfer any of its property or assets to Carrier1 International or
    any other Restricted Subsidiary.


    The foregoing provisions shall not restrict any encumbrances or
restrictions:


        (1) existing on the Closing Date, including under the indentures or any
    other agreements or instruments in effect on the Closing Date, and any
    refinancings of such agreements or instruments; PROVIDED that the
    encumbrances and restrictions in any such refinancings are no less favorable
    in any


                                      119
<PAGE>

    material respect to the holders than those encumbrances or restrictions that
    are then in effect and that are being refinanced;



        (2) existing under or by reason of applicable law or any requirement of
    any applicable governmental regulatory authority;



        (3) existing with respect to any Person, or any property or assets,
    acquired by Carrier1 International or any Restricted Subsidiary, existing at
    the time of such acquisition and not incurred in contemplation thereof,
    which encumbrances or restrictions are not applicable (A) in the case of an
    acquisition of such Person, to any other Person or (B) in the case of an
    acquisition of such property or assets, any other property or assets;



        (4) in the case of clause (4) (and, solely with respect to clauses (A),
    (B) and (D) of this clause (4), clause (1)) of the first paragraph of this
    "Limitation on Dividend and Other Payment Restrictions Affecting Restricted
    Subsidiaries" covenant,



           (A) that restrict in a customary manner the subletting, assignment or
       transfer of any property or asset that is, or is subject to, a lease,
       license, conveyance or contract or similar property or asset,



           (B) existing by virtue of any transfer of, agreement to transfer,
       option or right with respect to, or Lien on, any property or assets of
       Carrier1 International or any Restricted Subsidiary not otherwise
       prohibited by the relevant Indenture,



           (C) arising or agreed to in the ordinary course of business, not
       relating to any Indebtedness, and that do not, individually or in the
       aggregate, detract from the value of property or assets of Carrier1
       International or any Restricted Subsidiary in any manner material to
       Carrier1 International or any Restricted Subsidiary or



           (D) arising under the terms of Indebtedness Incurred under clause (7)
       of the second paragraph of the "Limitation on Indebtedness" covenant that
       restrict the transfer of the property or assets acquired with such
       Indebtedness;



        (5) with respect to a Restricted Subsidiary and imposed pursuant to an
    agreement that has been entered into for the sale or disposition of all or
    substantially all of the Capital Stock of, or property and assets of, such
    Restricted Subsidiary;



        (6) contained in the terms of any Indebtedness or any agreement pursuant
    to which such Indebtedness was issued, or any agreement relating to the
    sale, disposition or financing of receivables, if



           (A) either (1) the encumbrance or restriction applies only in the
       event of a payment default or a default with respect to a financial
       covenant contained in the terms of such Indebtedness or agreement or (2)
       Carrier1 International in good faith determines (as set forth in a Board
       Resolution) that any such encumbrance or restriction will not materially
       affect Carrier1 International's ability to make principal or interest
       payments on the notes and



           (B) the encumbrance or restriction is not materially more
       disadvantageous to the holders of the notes than is customary in
       comparable financings (as determined by Carrier1 International in good
       faith);



        (7) restrictions on cash or other deposits or net worth imposed by
    customers under contracts entered into in the ordinary course of business;
    or



        (8) customary provisions in joint venture agreements and other similar
    agreements entered into in the ordinary course of business.


                                      120
<PAGE>

Nothing contained in this "Limitation on Dividend and Other Payment Restrictions
Affecting Restricted Subsidiaries" covenant shall prevent Carrier1 International
or any Restricted Subsidiary from:


        (1) creating, incurring, assuming or suffering to exist any Liens
    otherwise permitted under the "Limitation on Liens" covenant or


        (2) restricting the sale or other disposition of property or assets of
    Carrier1 International or any of its Restricted Subsidiaries that secure
    Indebtedness of Carrier1 International or any of its Restricted
    Subsidiaries.


    LIMITATION ON THE ISSUANCE AND SALE OF CAPITAL STOCK OF RESTRICTED
     SUBSIDIARIES


    Carrier1 International will not sell, and will not permit any Restricted
Subsidiary, directly or indirectly, to issue or sell, any shares of Capital
Stock of a Restricted Subsidiary (including options, warrants or other rights to
purchase shares of such Capital Stock) except:



        (1) to Carrier1 International or a Wholly Owned Restricted Subsidiary;



        (2) issuances of director's qualifying shares or issuances or sales to
    foreign nationals of shares of Capital Stock of foreign Restricted
    Subsidiaries, to the extent required by applicable law;



        (3) if, immediately after giving effect to such issuance or sale, such
    Restricted Subsidiary would no longer constitute a Restricted Subsidiary and
    any Investment in such Person remaining after giving effect to such issuance
    or sale would have been permitted to be made under the "Limitation on
    Restricted Payments" covenant if made on the date of such issuance or sale;
    or



        (4) issuances or sales of Common Stock of a Restricted Subsidiary,
    provided that Carrier1 International or such Restricted Subsidiary applies
    the Net Cash Proceeds, if any, of any such sale in accordance with clause
    (A) or (B) of the "Limitation on Asset Sales" covenant described below.


    LIMITATION ON ISSUANCES OF GUARANTEES BY RESTRICTED SUBSIDIARIES


    Carrier1 International will not permit any Restricted Subsidiary, directly
or indirectly, to Guarantee any Indebtedness of Carrier1 International or any
Subsidiary Guarantor which is PARI PASSU with or expressly subordinate in right
of payment to the notes or any notes Guarantee ("Guaranteed Indebtedness"),
unless:



        (1) such Restricted Subsidiary simultaneously executes and delivers a
    supplemental indenture to the relevant indenture providing for a Guarantee
    (a "Subsidiary Guarantee") of payment of the notes by such Restricted
    Subsidiary and



        (2) such Restricted Subsidiary waives and will not in any manner
    whatsoever claim or take the benefit or advantage of, any rights of
    reimbursement, indemnity or subrogation or any other rights against Carrier1
    International or any other Restricted Subsidiary as a result of any payment
    by such Restricted Subsidiary under its Subsidiary Guarantee, until payment
    in full of the outstanding principal amount of such notes and any premium or
    accrued and unpaid interest thereon then due and owing;


PROVIDED that this paragraph shall not be applicable to any Guarantee of any
Restricted Subsidiary:

           (a) that existed at the time such Person became a Restricted
       Subsidiary and was not Incurred in connection with, or in contemplation
       of, such Person becoming a Restricted Subsidiary or


           (b) of Indebtedness Incurred pursuant to clause (1) of the second
       paragraph of the "Limitation on Indebtedness" covenant.



If the Guaranteed Indebtedness is (A) PARI PASSU with the notes, then the
Guarantee of such Guaranteed Indebtedness shall be PARI PASSU with, or
subordinated to, the Subsidiary Guarantee or (B) subordinated to


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the notes, then the Guarantee of such Guaranteed Indebtedness shall be
subordinated to the Subsidiary Guarantee at least to the extent that the
Guaranteed Indebtedness is subordinated to the notes.


    Notwithstanding the foregoing, any Subsidiary Guarantee by a Restricted
Subsidiary may provide by its terms that it shall be automatically and
unconditionally released and discharged upon:


        (1) any sale, exchange or transfer (including by way of merger or
    consolidation), to any Person not an Affiliate of Carrier1 International, of
    all of Carrier1 International's and each Restricted Subsidiary's Capital
    Stock in, or all or substantially all the assets of, such Restricted
    Subsidiary (which sale, exchange, transfer or other transaction is not
    prohibited by the relevant indenture),



        (2) the legal or covenant defeasance of the notes or satisfaction and
    discharge of the relevant indenture, subject to customary contingent
    reinstatement provisions,



        (3) the release or discharge of the Guarantee which resulted in the
    creation of such Subsidiary Guarantee, except a discharge or release by or
    as a result of payment under such Guarantee or



        (4) upon the merger or consolidation of such Subsidiary Guarantor with
    and into Carrier1 International or another Subsidiary Guarantor that is the
    surviving Person in such merger or consolidation.


    LIMITATION ON TRANSACTIONS WITH SHAREHOLDERS AND AFFILIATES


    Carrier1 International will not, and will not permit any Restricted
Subsidiary to, directly or indirectly, enter into, renew or extend any
transaction (including, without limitation, the purchase, sale, lease or
exchange of property or assets, or the rendering of any service) with any holder
(or any Affiliate of such holder) of 5% or more of any class of Capital Stock of
Carrier1 International or with any Affiliate of Carrier1 International or any
Restricted Subsidiary, except upon fair and reasonable terms that taken as a
whole are no less favorable to Carrier1 International or such Restricted
Subsidiary than could be obtained, at the time of such transaction or, if such
transaction is pursuant to a written agreement, at the time of the execution of
the agreement providing therefor, in a comparable arm's-length transaction with
a Person that is not such a holder or an Affiliate.


    The foregoing limitation does not limit, and shall not apply to:


        (1) transactions (A) approved by a majority of the disinterested members
    of the Board of Directors or (B) for which Carrier1 International or a
    Restricted Subsidiary delivers to the relevant trustee a written opinion of
    a nationally recognized investment banking or appraisal firm stating that
    the transaction is fair to Carrier1 International or such Restricted
    Subsidiary from a financial point of view, or is upon terms that taken as a
    whole are no less favorable to Carrier1 International or such Restricted
    Subsidiary than could be obtained in a comparable arm's-length transaction;



        (2) any transaction solely between or among Carrier1 International and
    any of its Wholly Owned Restricted Subsidiaries or solely between or among
    Wholly Owned Restricted Subsidiaries;



        (3) the payment of reasonable and customary regular fees to directors of
    Carrier1 International who are not employees of Carrier1 International;



        (4) any payments or other transactions pursuant to any tax-sharing
    agreement between Carrier1 International and any other Person with which
    Carrier1 International files a consolidated tax return or with which
    Carrier1 International is part of a consolidated group for tax purposes;



        (5) any Restricted Payments (or a transaction excluded from the
    definition of the term "Restricted Payments") not prohibited by the
    "Limitation on Restricted Payments" covenant;


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<PAGE>

        (6) transactions consisting of or pursuant to employment or benefit
    agreements, plans, programs or arrangements for or with, or indemnification
    or contribution obligations to, employees, officers or directors in the
    ordinary course of business;



        (7) the entering into of the Securities Purchase and Cancellation
    Agreement, the 1999 Share Option Plan, the Securities Purchase Agreement,
    the Registration Rights Agreement and the Securityholders' Agreement, as
    described in the offering memorandum relating to the original offering, and
    performance of the obligations and the transactions contemplated thereby; or



        (8) issuances or sales of Capital Stock (other than Disqualified Stock)
    of Carrier1 International or options, warrants or other rights to acquire
    such Capital Stock.



Notwithstanding the foregoing, any transaction or series of related transactions
covered by the first paragraph of this "Limitation on Transactions with
Shareholders and Affiliates" covenant and not covered by clauses (2) through (8)
of this paragraph, the aggregate amount of which exceeds $2 million in value,
must be approved or determined to be fair in the manner provided for in clause
(1)(A) or (B) above.


    LIMITATION ON LIENS


    Carrier1 International will not, and will not permit any Restricted
Subsidiary to, create, incur, assume or suffer to exist any Lien on any of its
assets or properties of any character (including, without limitation, licenses),
or any shares of Capital Stock or Indebtedness of any Restricted Subsidiary,
without making effective provision for all of the notes and all other amounts
due under the relevant indenture to be directly secured equally and ratably with
(or, if the obligation or liability to be secured by such Lien is expressly
subordinated in right of payment to the notes, prior to) the obligation or
liability secured by such Lien.


    The foregoing limitation does not apply to:


        (1) Liens existing on the Closing Date;



        (2) Liens granted after the Closing Date on any assets or Capital Stock
    of Carrier1 International or its Restricted Subsidiaries created in favor of
    the holders;



        (3) Liens with respect to the assets of a Restricted Subsidiary granted
    by such Restricted Subsidiary to Carrier1 International or a Wholly Owned
    Restricted Subsidiary to secure Indebtedness owing to Carrier1 International
    or such other Restricted Subsidiary;



        (4) Liens securing Indebtedness which is permitted to be Incurred under
    clause (3) of the second paragraph of the "Limitation on Indebtedness"
    covenant to refinance secured Indebtedness; PROVIDED that such Liens do not
    extend to or cover any property or assets of Carrier1 International or any
    Restricted Subsidiary other than the property or assets securing the
    Indebtedness being refinanced;



        (5) Liens on the Capital Stock of, or any property or assets of, a
    Restricted Subsidiary securing Indebtedness of such Restricted Subsidiary
    (or obligations in respect thereof) permitted under the "Limitation on
    Indebtedness" covenant; or



        (6) Permitted Liens.


    LIMITATION ON SALE-LEASEBACK TRANSACTIONS


    Carrier1 International will not, and will not permit any Restricted
Subsidiary to, enter into any sale-leaseback transaction involving any of its
assets or properties whether now owned or hereafter acquired, whereby Carrier1
International or a Restricted Subsidiary sells or transfers such assets or
properties more than one year after acquiring such assets or properties and then
or thereafter leases such assets or properties or any part thereof or any other
assets or properties which Carrier1 International or


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<PAGE>
such Restricted Subsidiary, as the case may be, intends to use for substantially
the same purpose or purposes as the assets or properties sold or transferred.

    The foregoing restriction does not apply to any sale-leaseback transaction
if:


        (1) the lease is for a period, including renewal rights, of not in
    excess of three years;



        (2) the lease secures or relates to industrial revenue or pollution
    control bonds;



        (3) the transaction is solely between Carrier1 International and any
    Wholly Owned Restricted Subsidiary or solely between Wholly Owned Restricted
    Subsidiaries; or



        (4) Carrier1 International or such Restricted Subsidiary, within 12
    months after the sale or transfer of any assets or properties is completed,
    applies an amount not less than the net proceeds received from such sale in
    accordance with clause (A) or (B) of the second paragraph of the "Limitation
    on Asset Sales" covenant described below.


    LIMITATION ON ASSET SALES


    Carrier1 International will not, and will not permit any Restricted
Subsidiary to, consummate any Asset Sale, unless:



        (1) the consideration received by Carrier1 International or such
    Restricted Subsidiary (including any Released Indebtedness and including by
    way of relief from or by any other Person assuming responsibilities for any
    liabilities other than Indebtedness ("Released Liabilities")) is at least
    equal to the fair market value of the assets sold or disposed of; PROVIDED
    that this clause (1) shall not apply to any sale, transfer or other
    disposition arising from foreclosure, condemnation or similar action with
    respect to any assets and



        (2) at least 75% of the consideration received (including any Released
    Indebtedness and Released Liabilities) consists of cash, Temporary Cash
    Investments or Released Indebtedness and Released Liabilities; PROVIDED,
    HOWEVER, that this clause (2) shall not apply to long-term assignments in
    capacity in a telecommunications network or other transfers of indefeasible
    rights of use, multiple investment units or dark fibers.



    In the event and to the extent that the Net Cash Proceeds received by
Carrier1 International or any of its Restricted Subsidiaries from one or more
Asset Sales occurring on or after the Closing Date in any period of 12
consecutive months exceed 10% of Adjusted Consolidated Net Tangible Assets
(determined as of the date closest to the commencement of such 12-month period
for which a consolidated balance sheet of Carrier1 International and its
Subsidiaries has been filed with the Commission or provided to the relevant
trustee pursuant to the "Commission Reports and Reports to Holders" covenant),
then Carrier1 International shall or shall cause the relevant Restricted
Subsidiary to:



        (1) within 12 months after the date Net Cash Proceeds so received exceed
    10% of Adjusted Consolidated Net Tangible Assets



           (A) apply an amount equal to such excess Net Cash Proceeds to
       permanently repay unsubordinated Indebtedness of Carrier1 International
       or any Restricted Subsidiary providing a notes Guarantee, or Indebtedness
       of any other Restricted Subsidiary, in each case owing to a Person other
       than Carrier1 International or any of its Restricted Subsidiaries or



           (B) invest an equal amount, or the amount not so applied pursuant to
       clause (A), (or enter into a definitive agreement committing to so invest
       within 12 months after the date of such agreement) in property or assets
       (other than current assets) of a nature or type or that are used in a
       business (or in a company having property and assets of a nature or type,
       or engaged in a business) similar or related to the nature or type of the
       property and assets of, or the business of, Carrier1 International and
       its Restricted Subsidiaries existing on the date of such investment (as
       determined in good faith by the Board of Directors, whose determination
       shall be conclusive and evidenced by a Board Resolution) and


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<PAGE>

        (2) apply (no later than the end of the 12-month period referred to in
    clause (1)) such excess Net Cash Proceeds (to the extent not applied or
    committed to be applied pursuant to clause (1)) as provided in the following
    paragraph of this "Limitation on Asset Sales" covenant.



The amount of such excess Net Cash Proceeds required to be applied (or to be
committed to be applied) during such 12-month period as set forth in clause (1)
of the preceding sentence and not applied or committed to be applied as so
required by the end of such period shall constitute "Excess Proceeds."



    If, as of the first day of any calendar month, the aggregate amount of
Excess Proceeds not theretofore subject to an Offer to Purchase pursuant to this
"Limitation on Asset Sales" covenant totals at least $5 million, Carrier1
International must commence, not later than the fifteenth Business Day of such
month, and consummate an Offer to Purchase from the holders of the notes (and if
and to the extent required by the terms of any Indebtedness that is PARI PASSU
with the notes or any notes Guarantee ("Pari Passu Indebtedness"), purchase,
redeem or repay such Pari Passu Indebtedness) on a PRO RATA basis an aggregate
principal amount of notes (and an amount of Pari Passu Indebtedness) equal to
the Excess Proceeds on such date, at a purchase price equal to 100% of the
principal amount of the notes (and the required amount of Pari Passu
Indebtedness) plus accrued interest (if any) to the Payment Date. If the
aggregate principal amount of the notes and aggregate principal amount of such
Pari Passu Indebtedness validly tendered and not withdrawn (or otherwise subject
to purchase, redemption or repayment) exceeds such Excess Proceeds, such Excess
Proceeds will be apportioned between the notes and such Pari Passu Indebtedness,
with the portion of such Excess Proceeds payable in respect of the notes to
equal the lesser of



        (x) the Excess Proceeds amount multiplied by a fraction, the numerator
    of which is the aggregate principal amount of the notes and the denominator
    of which is the sum of the aggregate principal amount of the notes and the
    aggregate principal amount of such Pari Passu Indebtedness and



        (y) the principal amount of notes validly tendered and not withdrawn.



    Any Excess Proceeds remaining after such Offer to Purchase is completed may
be applied to fund any general corporate purpose not prohibited by the relevant
indenture.


    For purposes of the first paragraph of this "Limitation on Asset Sales"
covenant:


        (1) securities received by Carrier1 International or any Restricted
    Subsidiary in any Asset Sale that are converted by Carrier1 International or
    such Restricted Subsidiary into cash within 12 months after such Asset Sale
    and



        (2) consideration consisting of Indebtedness of Carrier1 International
    or any Restricted Subsidiary, shall be deemed to be cash.


REPURCHASE OF NOTES UPON A CHANGE OF CONTROL


    Carrier1 International must commence, within 30 days of the occurrence of a
Change of Control, and consummate an Offer to Purchase for all notes then
outstanding, at a purchase price equal to 101% of the principal amount thereof,
PLUS accrued and unpaid interest (if any) to the Payment Date.



    The terms of other Indebtedness of Carrier1 International and its
Subsidiaries may provide that the occurrence of a Change of Control constitutes
a default thereunder, prohibit certain events that would constitute a Change of
Control, or require such Indebtedness to be repurchased or repaid upon a Change
of Control. Moreover, the exercise by the holders of their right to require
Carrier1 International to repurchase the notes could cause a default under the
terms of such other Indebtedness, even if the Change of Control itself does not,
due to the financial effect of such repurchase on Carrier1 International. The
above covenant requiring Carrier1 International to repurchase the notes will,
unless consents are obtained, require Carrier1 International to repay all
indebtedness then outstanding which by its terms would prohibit such note
repurchase, either prior to or concurrently with such note repurchase. Carrier1
International's


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<PAGE>

ability to pay cash to the holders upon a Change of Control may be limited by
Carrier1 International's then existing financial resources. There can be no
assurance that Carrier1 International will have sufficient funds available at
the time of any Change of Control to make any debt payment (including
repurchases of notes) required by the foregoing covenant or under the terms of
any other Indebtedness.



    The Change of Control purchase feature is a result of negotiations between
Carrier1 International and the placement agents. Carrier1 International has no
present plans to engage in a transaction involving a Change of Control, although
it is possible that Carrier1 International would decide to do so in the future.
Subject to the limitations contained in the indentures, Carrier1 International
could, in the future, enter into certain transactions, including acquisitions,
refinancings or recapitalizations, that would not constitute a Change of Control
under the indentures, but that could increase the amount of indebtedness
outstanding at such time or otherwise affect Carrier1 International's capital
structure or credit ratings.


COMMISSION REPORTS AND REPORTS TO HOLDERS


    At all times from and after the earlier of (1) the date of the commencement
of an exchange offer or the effectiveness of a Shelf Registration Statement (the
"Registration") and (2) the date that is six months after the Closing Date, in
either case, whether or not Carrier1 International is then required to file
reports with the Commission, Carrier1 International shall file with the
Commission to the extent then permitted by the Securities Exchange Act of 1934,
as amended, and by the Commission, all such information on an appropriate
available form as it would be required to file with the Commission by Sections
13(a) or 15(d) under the Securities Exchange Act of 1934 as if it were a U.S.
company and subject thereto including information required by annual, quarterly
and current reports whether or not required to be so filed. Carrier1
International shall supply the relevant trustee and each holder or shall supply
to the relevant trustee for forwarding to all holders, without cost to such
holders, copies of such reports and other information. In addition, at all times
prior to the earlier of the date of the Registration and the date that is six
months after the Closing Date, Carrier1 International shall, at its cost, supply
the relevant trustee and each holder or shall supply to the relevant trustee for
forwarding to all holders, without cost to such holders, quarterly and annual
reports substantially equivalent to those described above or which would
otherwise be required by the Exchange Act commencing with the report for the
fiscal quarter ending immediately after the Closing Date; provided that Carrier1
International may deliver copies of the registration statement (including
pre-effective amendments thereto) with respect to the exchange offer to the
extent it contains the information that would have been required in such
reports. In addition, at all times prior to the Registration, upon the request
of any holder or any prospective purchaser of the notes designated by a holder,
Carrier1 International shall supply to such holder or such prospective purchaser
the information required under Rule 144A under the Securities Act.


EVENTS OF DEFAULT

    The following events are defined as "Events of Default" in the relevant
Indenture:


        (a) default in the payment of principal of (or premium, if any, on) any
    note when the same becomes due and payable at maturity, upon acceleration,
    redemption or otherwise;



        (b) default in the payment of interest on any note when the same becomes
    due and payable, and such default continues for a period of 30 days;
    provided that a failure to make any of the first five scheduled interest
    payments on the relevant series of notes on the applicable Interest Payment
    Date will constitute an Event of Default with no grace or cure period;



        (c) default in the performance or breach of the provisions of such
    indenture applicable to mergers, consolidations and transfers of all or
    substantially all of the assets of Carrier1 International or the failure to
    make or consummate an Offer to Purchase when required in accordance with the
    "Limitation on Asset Sales" or "Repurchase of Notes upon a Change of
    Control" covenant;


                                      126
<PAGE>

        (d) Carrier1 International defaults in the performance of or breaches
    any other covenant or agreement of Carrier1 International in such indenture
    or under the relevant notes (other than a default specified in clause (a),
    (b) or (c) above) or the relevant Pledge Agreement and such default or
    breach continues for a period of 30 consecutive days after written notice by
    the relevant trustee or the holders of 25% or more in aggregate principal
    amount of the relevant series of notes;



        (e) there occurs with respect to any issue or issues of Indebtedness of
    Carrier1 International or any Significant Subsidiary having an outstanding
    principal amount of $10 million or more in the aggregate for all such issues
    of all such Persons, whether such Indebtedness now exists or shall hereafter
    be created, (A) an event of default that has caused the holder thereof to
    declare such Indebtedness to be due and payable prior to its Stated Maturity
    and such Indebtedness has not been discharged in full or such acceleration
    has not been rescinded or annulled within 30 days of such acceleration
    and/or (B) the failure to make a principal payment at the final (but not any
    interim) fixed maturity and such defaulted payment shall not have been made,
    waived or extended within 30 days of such payment default;



        (f) any final judgment or order (not covered by insurance) for the
    payment of money in excess of $10 million in the aggregate for all such
    final judgments or orders against all such Persons (treating any
    deductibles, self-insurance or retention as not so covered) shall be
    rendered against Carrier1 International or any Significant Subsidiary and
    shall not be paid or discharged, and there shall be any period of 60
    consecutive days following entry of the final judgment or order that causes
    the aggregate amount for all such final judgments or orders outstanding and
    not paid or discharged against all such Persons to exceed $10 million during
    which a stay of enforcement of such final judgment or order, by reason of a
    pending appeal or otherwise, shall not be in effect;


        (g) a court having jurisdiction in the premises enters a decree or order
    for


           (A) relief in respect of Carrier1 International or any Significant
       Subsidiary in an involuntary case under any applicable bankruptcy,
       insolvency or other similar law now or hereafter in effect,



           (B) appointment of a receiver, liquidator, assignee, custodian,
       trustee, sequestrator or similar official of Carrier1 International or
       any Significant Subsidiary or for all or substantially all of the
       property and assets of Carrier1 International or any Significant
       Subsidiary or



           (C) the winding up or liquidation of the affairs of Carrier1
       International or any Significant Subsidiary and, in each case, such
       decree or order shall remain unstayed and in effect for a period of 30
       consecutive days; or



        (h) Carrier1 International or any Significant Subsidiary


           (A) commences a voluntary case under any applicable bankruptcy,
       insolvency or other similar law now or hereafter in effect, or consents
       to the entry of an order for relief in an involuntary case under any such
       law,


           (B) consents to the appointment of or taking possession by a
       receiver, liquidator, assignee, custodian, trustee, sequestrator or
       similar official of Carrier1 International or any Significant Subsidiary
       or for all or substantially all of the property and assets of Carrier1
       International or any Significant Subsidiary or


           (C) effects any general assignment for the benefit of creditors; or


        (i) the relevant Pledge Agreement shall cease to be in full force and
    effect or enforceable in accordance with its terms, other than in accordance
    with its terms.



    If an Event of Default (other than an Event of Default specified in clause
(g) or (h) above that occurs with respect to Carrier1 International) occurs and
is continuing under the relevant indenture, the relevant trustee or the holders
of at least 25% in aggregate principal amount of the dollar notes or the Euro
notes,


                                      127
<PAGE>

as the case may be, then outstanding, by written notice to Carrier1
International (and to the relevant trustee if such notice is given by the
holders), may, and such trustee at the request of such holders shall, declare
the principal of, and premium, if any, and accrued and unpaid interest on the
relevant notes to be immediately due and payable. Upon a declaration of
acceleration, such principal of, and premium, if any, and accrued and unpaid
interest shall be immediately due and payable. In the event of a declaration of
acceleration because an Event of Default set forth in clause (e) above has
occurred and is continuing, such declaration of acceleration shall be
automatically rescinded and annulled if the event of default triggering such
Event of Default pursuant to clause (e) shall be remedied or cured by Carrier1
International or the relevant Significant Subsidiary or waived by the holders of
the relevant Indebtedness within 60 days after the declaration of acceleration
with respect thereto. If an Event of Default specified in clause (g) or (h)
above occurs with respect to Carrier1 International, the principal of, and
premium, if any, and accrued and unpaid interest on the notes then outstanding
shall IPSO FACTO become and be immediately due and payable without any
declaration or other act on the part of either trustee or any holder. The
holders of at least a majority in principal amount of the outstanding notes of
the relevant series, by written notice to Carrier1 International and to the
relevant trustee, may waive all past defaults and rescind and annul a
declaration of acceleration and its consequences if:



        (1) all existing Events of Default, other than the nonpayment of the
    principal of, premium, if any, and interest on the relevant notes that have
    become due solely by such declaration of acceleration, have been cured or
    waived and



        (2) the rescission would not conflict with any judgment or decree of a
    court of competent jurisdiction. For information as to the waiver of
    defaults, see "--Modification and Waiver."



    The holders of at least a majority in aggregate principal amount of the
outstanding dollar notes or Euro notes, as the case may be, may direct the time,
method and place of conducting any proceeding for any remedy available to the
relevant trustee or exercising any trust or power conferred on such trustee.
However, such trustee may refuse to follow any direction that conflicts with law
or the relevant indenture, that may involve such trustee in personal liability,
or that such trustee determines in good faith may be unduly prejudicial to the
rights of holders of the dollar notes or Euro notes, as the case may be, not
joining in the giving of such direction and may take any other action it deems
proper that is not inconsistent with any such direction received from holders of
the relevant notes. A holder may not pursue any remedy with respect to the
relevant indenture or the relevant notes unless:



        (1) the holder gives the relevant trustee written notice of a continuing
    Event of Default;



        (2) the holders of at least 25% in aggregate principal amount of
    outstanding dollar notes or Euro notes, as the case may be, make a written
    request to such trustee to pursue the remedy;



        (3) such holder or holders offer such trustee indemnity satisfactory to
    such trustee against any costs, liability or expense;



        (4) such trustee does not comply with the request within 60 days after
    receipt of the request and the offer of indemnity; and



        (5) during such 60-day period, the holders of a majority in aggregate
    principal amount of the outstanding dollar notes or Euro notes, as the case
    may be, do not give such trustee a direction that is inconsistent with the
    request.



However, such limitations do not apply to the right of any holder of a note to
receive payment of the principal of, and premium, if any, or interest on, such
note or to bring suit for the enforcement of any such payment, on or after the
due date expressed in the notes, which right shall not be impaired or affected
without the consent of the holder.



    Each indenture requires certain officers of Carrier1 International to
certify, on or before a date not more than 90 days after the end of each fiscal
year, that a review has been conducted of the activities of


                                      128
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Carrier1 International and its Restricted Subsidiaries and Carrier1
International's and its Restricted Subsidiaries' performance under such
indenture and that Carrier1 International has fulfilled all obligations
thereunder, or, if there has been a default in the fulfillment of any such
obligation, specifying each such default and the nature and status thereof.
Carrier1 International is also obligated to notify the relevant trustee of any
default or defaults in the performance of any covenants or agreements under the
relevant indenture.


CONSOLIDATION, MERGER AND SALE OF ASSETS


    Carrier1 International will not consolidate with, merge with or into, or
sell, convey, transfer, lease or otherwise dispose of all or substantially all
of its property and assets (as an entirety or substantially an entirety in one
transaction or a series of related transactions) to, any Person or permit any
Person to merge with or into Carrier1 International unless:



        (1) Carrier1 International shall be the continuing Person, or the Person
    (if other than Carrier1 International) formed by such consolidation or into
    which Carrier1 International is merged or that acquired or leased such
    property and assets of Carrier1 International shall be a corporation
    organized and validly existing under the laws of the Kingdom of the
    Netherlands (including the Netherlands Antilles), Bermuda, Canada,
    Switzerland, any member state of the European Union or the United States of
    America or any jurisdiction thereof and shall expressly assume, by a
    supplemental indenture, executed and delivered to the relevant trustee, all
    of the obligations of Carrier1 International on the relevant series of notes
    and under the relevant indenture;



        (2) immediately after giving effect to such transaction, no Default or
    Event of Default shall have occurred and be continuing;



        (3) immediately after giving effect to such transaction on a pro forma
    basis, Carrier1 International or any Person becoming the successor obligor
    of the notes shall have a Consolidated Net Worth equal to or greater than
    the Consolidated Net Worth of Carrier1 International immediately prior to
    such transaction; PROVIDED that this clause (3) shall only apply to a sale
    of less than all of the assets of Carrier1 International;



        (4) immediately after giving effect to such transaction on a pro forma
    basis Carrier1 International, or any Person becoming the successor obligor
    on such notes, as the case may be, could Incur at least $1.00 of
    Indebtedness under the first paragraph of the "Limitation on Indebtedness"
    covenant; PROVIDED that this clause (4) shall not apply to a consolidation,
    merger or sale of all (but not less than all) of the assets of Carrier1
    International if all Liens and Indebtedness of Carrier1 International or any
    Person becoming the successor obligor of the notes, as the case may be, and
    its Restricted Subsidiaries outstanding immediately after such transaction
    would, if Incurred at such time, have been permitted to be Incurred (and all
    such Liens and Indebtedness, other than Liens and Indebtedness of Carrier1
    International and its Restricted Subsidiaries outstanding immediately prior
    to the transaction, shall be deemed to have been Incurred) for all purposes
    of the relevant indenture; and



        (5) Carrier1 International delivers to the relevant trustee an Officers'
    Certificate (attaching the arithmetic computations to demonstrate compliance
    with clauses (3) and (4) above) and Opinion of Counsel, in each case to the
    effect that such consolidation, merger or transfer and such supplemental
    indenture complies with this provision and that all conditions precedent
    provided for in this paragraph relating to such transaction have been
    complied with;



PROVIDED, HOWEVER, that (x) in giving any such opinion such counsel may rely on
an Officers' Certificate as to compliance with the foregoing clauses (2), (3)
and (4) and as to any matters of fact and (y) clauses (3) and (4) above will not
apply if, in the good faith determination of the Board of Directors of Carrier1
International, whose determination shall be evidenced by a Board Resolution, the
principal purpose of


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<PAGE>

such transaction is to change the jurisdiction of organization of Carrier1
International, and such transaction does not have as one of its purposes the
evasion of the foregoing limitations.


DEFEASANCE

    DEFEASANCE AND DISCHARGE


    Each indenture provides that Carrier1 International will be deemed to have
paid and will be discharged from any and all obligations in respect of the notes
issued thereunder on the 123rd day after the deposit referred to below, and the
provisions of the relevant indenture will no longer be in effect with respect to
such notes (except for, among other matters, certain obligations to register the
transfer or exchange of such notes, to replace stolen, lost or mutilated notes,
to maintain paying agencies and to hold monies for payment in trust) if, among
other things:



        (A) Carrier1 International has deposited with the relevant trustee, in
    trust, money and/or U.S. Government Obligations, in the case of dollar
    notes, or European Government Obligations, in the case of Euro notes, that
    through the payment of interest and principal in respect thereof in
    accordance with their terms will provide money in an amount sufficient to
    pay the principal of, premium, if any, and accrued interest on the relevant
    notes



           (1) on the Stated Maturity of such payments in accordance with the
       terms of the relevant indenture and such notes or



           (2) on any earlier Redemption Date pursuant to the terms of the
       relevant indenture and such notes;



       PROVIDED that Carrier1 International has provided the relevant trustee
       with irrevocable instructions to redeem all of the outstanding notes of
       such series on such Redemption Date,



        (B) Carrier1 International has delivered to the relevant trustee



           (1) either (x) an Opinion of Counsel to the effect that holders will
       not recognize income, gain or loss for federal income tax purposes as a
       result of Carrier1 International's exercise of its option under this
       "Defeasance" provision and will be subject to federal income tax on the
       same amount and in the same manner and at the same times as would have
       been the case if such deposit, defeasance and discharge had not occurred,
       which Opinion of Counsel must be based upon (and accompanied by a copy
       of) a ruling of the Internal Revenue Service to the same effect unless
       there has been a change in applicable federal income tax law after the
       Closing Date such that a ruling is no longer required or (y) a ruling
       directed to the relevant trustee received from the Internal Revenue
       Service to the same effect as the aforementioned Opinion of Counsel and



           (2) an Opinion of Counsel to the effect that the creation of the
       defeasance trust does not violate the Investment Company Act of 1940 and
       after the passage of 123 days following the deposit, the trust fund will
       not be subject to the effect of Section 547 of the United States
       Bankruptcy Code or Section 15 of the New York Debtor and Creditor Law,



        (C) immediately after giving effect to such deposit on a pro forma
    basis, no Event of Default, or event that after the giving of notice or
    lapse of time or both would become an Event of Default, shall have occurred
    and be continuing on the date of such deposit or during the period ending on
    the 123rd day after the date of such deposit, and such deposit shall not
    result in a breach or violation of, or constitute a default under, any other
    material agreement or instrument to which Carrier1 International or any of
    its Subsidiaries is a party or by which Carrier1 International or any of its
    Subsidiaries is bound and


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<PAGE>

        (D) if at such time the relevant notes are listed on a national
    securities exchange, Carrier1 International has delivered to the relevant
    trustee an Opinion of Counsel to the effect that the relevant notes will not
    be delisted as a result of such deposit, defeasance and discharge.


    DEFEASANCE OF CERTAIN COVENANTS AND CERTAIN EVENTS OF DEFAULT


    Each indenture further provides that the provisions of such indenture will
no longer be in effect with respect to clauses (3) and (4) under "Consolidation,
Merger and Sale of Assets" and all the covenants described herein under
"Covenants" and "Repurchase of Notes upon a Change of Control," clause (c) under
"Events of Default" with respect to such clauses (3) and (4) under
"Consolidation, Merger and Sale of Assets" and with respect to the "Limitation
on Asset Sales" and "Repurchase of Notes upon a Change of Control" covenants,
clause (d) under "Events of Default" with respect to such other covenants and
clauses (e) and (f) under "Events of Default" shall be deemed not to be Events
of Default upon, among other things, the deposit with the relevant trustee, in
trust, of money and/or U.S. Government Obligations in the case of dollar notes,
and European Government Obligations, in the case of Euro notes, that through the
payment of interest and principal in respect thereof in accordance with their
terms will provide money in an amount sufficient to pay the principal of,
premium, if any, and accrued interest on the relevant notes



        (1) on the Stated Maturity of such payments in accordance with the terms
    of the relevant indenture and the notes or



        (2) on any earlier Redemption Date pursuant to the terms of the relevant
    indenture and such notes, PROVIDED that Carrier1 International has provided
    the relevant trustee with irrevocable instructions to redeem all of the
    outstanding notes of such series on such Redemption Date, the satisfaction
    of the provisions described in clauses (B)(2), (C) and (D) of the preceding
    paragraph and the delivery by Carrier1 International to the relevant trustee
    of an Opinion of Counsel to the effect that, among other things, the holders
    will not recognize income, gain or loss for federal income tax purposes as a
    result of such deposit and defeasance of certain covenants and Events of
    Default and will be subject to federal income tax on the same amount and in
    the same manner and at the same times as would have been the case if such
    deposit and defeasance had not occurred.


    DEFEASANCE AND CERTAIN OTHER EVENTS OF DEFAULT


    In the event Carrier1 International exercises its option to omit compliance
with certain covenants and provisions of either indenture with respect to the
relevant series of notes as described in the immediately preceding paragraph and
such notes are declared due and payable because of the occurrence of an Event of
Default that remains applicable, the amount of money and/or U.S. Government
Obligations, in the case of dollar notes, and European Government Obligations,
in the case of Euro notes, on deposit with the relevant trustee will be
sufficient to pay amounts due on such notes at the time of their Stated Maturity
or earlier Redemption Date but may not be sufficient to pay amounts due on such
notes at the time of the acceleration resulting from such Event of Default.
However, Carrier1 International will remain liable for such payments.


MODIFICATION AND WAIVER


    Modifications and amendments of either indenture or either Pledge Agreement
may be made by Carrier1 International and the relevant trustee with the consent
of the holders of not less than a majority in aggregate principal amount of the
outstanding dollar notes or Euro notes, as the case may be; PROVIDED, HOWEVER,
that no such modification or amendment may, without the consent of each holder
affected thereby:



        (1) change the Stated Maturity of the principal of, or any installment
    of interest on, any note,



        (2) reduce the principal amount of, or premium, if any, or interest on,
    any note,


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<PAGE>

        (3) change the place or currency of payment of principal of, or premium,
    if any, or interest on, any note,



        (4) impair the right to institute suit for the enforcement of any
    payment on or after the Stated Maturity (or, in the case of a redemption, on
    or after the Redemption Date) of any note,



        (5) reduce the above-stated percentage of outstanding notes the consent
    of whose holders is necessary to modify or amend the applicable indenture,



        (6) waive a default in the payment of principal of, or premium, if any,
    or interest on, the notes,



        (7) release any collateral subject to the relevant Pledge Agreement
    (other than as contemplated thereby), or



        (8) reduce the percentage or aggregate principal amount of outstanding
    notes the consent of whose holders is necessary for waiver of compliance
    with certain provisions of the applicable indenture or for waiver of certain
    defaults.


ADDITIONAL AMOUNTS


    All payments made by Carrier1 International under or with respect to the
notes will be made free and clear of and without withholding or deduction for or
on account of any present or future tax, duty, levy, impost, assessment, or
other governmental charge (including penalties, interest and other liabilities
related thereto) (collectively, "Taxes") imposed or levied by or on behalf of
Luxembourg or any other jurisdiction in which Carrier1 International is
organized or is a resident for tax purposes or by any government authority or
political subdivision or territory or possession or agency therein or thereof
having the power to tax (each, a "Taxing Authority"), unless Carrier1
International is required to withhold or deduct Taxes by law or by the
interpretation or administration thereof.



    If Carrier1 International is required to withhold or deduct any amount for
or on account of Taxes imposed by a Taxing Authority within Luxembourg or within
any other jurisdiction in which Carrier1 International is organized or is a
resident for tax purposes, from any payment made under or with respect to the
notes, Carrier1 International will pay such additional amounts ("Additional
Amounts") as may be necessary so that the net amount received by each holder of
notes after such withholding or deduction will not be less than the amount the
holder and beneficial owner would have received if such Taxes had not been
withheld or deducted; PROVIDED that no Additional Amounts will be payable with
respect to a payment made to a holder of notes or to a third party on behalf of
a holder, with respect to:



        (a) any Taxes that would not have been so imposed but for the existence
    of any present or former connection between such holder and the jurisdiction
    imposing such tax (other than the mere receipt of such payment or the
    ownership or holding outside of Luxembourg of such note);


        (b) any estate, inheritance, gift, sales, excise, transfer, personal
    property tax or similar tax, assessment or governmental charge;


        (c) any Taxes payable otherwise than by deduction or withholding from
    payments of principal of, premium, if any, or interest on such note; or



        (d) Taxes that would not have been imposed but for the failure of the
    holder or beneficial owner of a note to comply, upon written request
    therefor furnished by Carrier1 International to the trustee, with any
    certification, identification, information, or other documentation
    requirement under law, regulation, administrative practice or an applicable
    treaty that is a precondition to exemption from, or reduction in the rate of
    the imposition, deduction or withholding of Taxes;


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<PAGE>
nor will Additional Amounts be paid:


        (1) if the payment under or with respect to the notes could have been
    made by another paying agent without such deduction or withholding,



        (2) if the payment under or with respect to the notes could have been
    made without such deduction or withholding if the beneficiary of the payment
    had presented the note for payment within 30 days after (A) the date on
    which such payment or such note became due and payable or (B) the date on
    which payment thereof is duly provided for, whichever is later (except to
    the extent that the holder would have been entitled to Additional Amounts
    had the note been presented on the last day of such 30 day period),



        (3) with respect to any payment under or with respect to the notes to
    any holder who is a fiduciary or partnership or any person other than the
    sole beneficial owner of such payment, to the extent that a beneficiary or
    settlor with respect to such fiduciary, a member of such a partnership or
    the beneficial owner of such payment would not have been entitled to the
    Additional Amounts had such beneficiary, settlor, member or beneficial owner
    been the actual holder of such note.



Carrier1 International will also (1) make such withholding or deduction and (2)
remit the full amount deducted or withheld to the relevant authority in
accordance with applicable law. Carrier1 International will use its reasonable
efforts to obtain certified copies of tax receipts evidencing the payment of any
Taxes so deducted or withheld from each Taxing Authority imposing such Taxes.
Carrier1 International will supply to the relevant trustee for forwarding to all
holders, without cost to such holders, within 60 days after the date the payment
of any Taxes so deducted or withheld is due pursuant to applicable law,
certified copies of tax receipts evidencing such payment by Carrier1
International or if, notwithstanding Carrier1 International's efforts to obtain
such receipts, the same are not obtainable, other evidence of such payments by
Carrier1 International.



    At least 30 days prior to each date on which any payment under or with
respect to the notes is due and payable, if Carrier1 International will be
obligated to pay Additional Amounts with respect to such payment, Carrier1
International will deliver to the relevant trustee an Officers' Certificate
stating the fact that such Additional Amounts will be payable, the amounts so
payable and will set forth such other information as is necessary to enable such
trustee to pay such Additional Amounts to holders of notes on the payment date.



    The foregoing provisions shall survive any termination or the discharge of
the relevant indenture and shall apply MUTATIS MUTANDIS to any jurisdiction in
which any successor Person to Carrier1 International is organized or is engaged
in business for tax purposes or any political subdivision or taxing authority or
agency thereof or therein.



    In addition, Carrier1 International will pay any stamp, issue, registration,
documentary or other similar taxes and duties, including interest and penalties,
payable in Luxembourg or any political subdivision thereof or therein in respect
of the creation, issue and offering of the Notes.



    Whenever in the relevant indenture, the notes or this prospectus there is
mentioned in any context, the payment of amounts based upon principal of,
premium, if any, or interest or of any other amount payable under or with
respect to any of the notes, such mention shall be deemed to include mention of
the payment of Additional Amounts to the extent that, in such context,
Additional Amounts are, were or would be payable in respect thereof.


GOVERNING LAW AND CONSENT TO JURISDICTION


    The notes and the indentures are governed by the laws of the State of New
York. Carrier1 International has appointed CT Corporation System, 1633 Broadway,
New York, NY 10019 as its agent for service of process in any suit, action or
proceeding with respect to the relevant indenture or the notes and


                                      133
<PAGE>
for actions brought under federal or state securities laws, in each case brought
in any federal or state court located in the City of New York and will agree to
submit to the jurisdiction of such courts.

NO PERSONAL LIABILITY OF INCORPORATORS, STOCKHOLDERS, OFFICERS, DIRECTORS, OR
  EMPLOYEES


    Each indenture provides that no recourse for the payment of the principal
of, or premium, if any, or interest on, any of the notes or for any claim based
thereon or otherwise in respect thereof, and no recourse under or upon any
obligation, covenant or agreement of Carrier1 International in such indenture,
or in any of the notes or because of the creation of any Indebtedness
represented thereby, shall be had against any incorporator, stockholder,
officer, director, employee or controlling person of Carrier1 International or
of any successor Person thereof. Each holder, by accepting the notes, waives and
releases all such liability.


CONCERNING THE TRUSTEE


    Each indenture provides that, except during the continuance of a Default,
the relevant trustee will not be liable, except for the performance of such
duties as are specifically set forth in such indenture. If an Event of Default
has occurred and is continuing, the relevant trustee will use the same degree of
care and skill in its exercise of the rights and powers vested in it under such
indenture as a prudent person would exercise under the circumstances in the
conduct of such person's own affairs.



    Each indenture and provisions of the Trust Indenture Act of 1939, as
amended, incorporated by reference therein contain limitations on the rights of
the relevant trustee, should it become a creditor of Carrier1 International, to
obtain payment of claims in certain cases or to realize on certain property
received by it in respect of any such claims, as security or otherwise. Such
trustee is permitted to engage in other transactions; PROVIDED, HOWEVER, that if
it acquires any conflicting interest, it must eliminate such conflict or resign.


                                      134
<PAGE>

                                    TAXATION


CERTAIN UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS


    The following discussion summarizes certain U.S. federal income tax
considerations relevant to the acquisition, ownership and disposition of the
notes. The discussion is based upon provisions of the U.S. Internal Revenue Code
of 1986, as amended (the "Code"), its legislative history, judicial authority,
current administrative rulings and practice, and existing and proposed Treasury
Regulations, including regulations concerning the treatment of debt instruments
issued with original issue discount (the "OID Regulations"), all as in effect
and existing on the date hereof. Legislative, judicial or administrative changes
or interpretations may be forthcoming that could alter or modify the conclusions
set forth below, possibly on a retroactive basis. This discussion assumes that
any notes are or will be held as capital assets (as defined in Section 1221 of
the Code) by the holders thereof. Except as otherwise described herein, this
discussion applies only to a person that is an initial holder who purchased
units pursuant to the original offering at the initial offering price and that
is (1) a citizen or resident of the United States, (2) a corporation or
partnership created or organized in or under the laws of the United States, any
State thereof or the District of Columbia, (3) an estate the income of which is
subject to U.S. federal income taxation regardless of source or (4) a trust if a
court within the United States is able to exercise primary supervision over the
administration of such trust and one or more U.S. persons has the authority to
control all substantial decisions of such trust (a "U.S. holder"). Non-U.S.
holders are advised to consult their own tax advisors regarding the tax
considerations incident to an investment in the notes. In addition, this
discussion does not purport to deal with all aspects of U.S. federal income
taxation that might be relevant to other particular holders in light of their
personal investment circumstances or status, nor does it discuss the U.S.
federal income tax consequences to certain types of holders that may be subject
to special rules under the U.S. federal income tax laws, such as persons owning
(or treated as owning) 10% or more of the total combined voting power of
Carrier1 International, financial institutions, insurance companies, dealers in
securities or foreign currency, tax-exempt organizations, foreign corporations
or nonresident alien individuals, or persons that hold notes that are a hedge
against, or that are hedged against, currency risk or that are part of a
straddle or conversion transaction, or persons whose functional currency is not
the U.S. dollar. Moreover, the effect of any applicable state, local or foreign
tax laws is not discussed.



    THE FOLLOWING DISCUSSION IS FOR GENERAL INFORMATION ONLY. EACH HOLDER IS
STRONGLY URGED TO CONSULT WITH ITS OWN TAX ADVISORS TO DETERMINE THE IMPACT OF
SUCH HOLDER'S PERSONAL TAX SITUATION ON THE ANTICIPATED TAX CONSEQUENCES,
INCLUDING THE TAX CONSEQUENCES UNDER STATE, LOCAL, FOREIGN OR OTHER TAX LAWS, OF
THE ACQUISITION, OWNERSHIP AND DISPOSITION OF NOTES.



    EXCHANGE OFFER.  The exchange of an old note by a U.S. holder for a new note
will not constitute a taxable exchange of the note, and thus a U.S. holder will
not recognize taxable gain or loss upon receipt of a new note, a U.S. holder's
holding period for a new note will include the holding period for the old note
so exchanged and such U.S. holder's adjusted tax basis in a new note will be the
same as such U.S. holder's adjusted tax basis in the old note so exchanged.


    ALLOCATION OF ISSUE PRICE BETWEEN NOTES AND WARRANTS


    The old notes were issued together with warrants and were treated as part of
an "investment unit" for U.S. Federal income tax purposes. Accordingly, the
total issue price of each unit was allocated between its components (i.e., notes
and warrants) on the basis of the fair market value of each such component as of
the issue date. The amounts so allocated were a U.S. holder's initial tax basis
in his warrants and notes, respectively, and the amount so allocated to the
notes was the issue price of the notes. The issue price of the dollar units for
U.S. federal income tax purposes was the price at which a substantial amount of
the dollar units were sold to the public (excluding sales to dealers,
underwriters, brokers and similar persons). The issue price of the Euro units
for U.S. federal income tax purposes was determined under the same


                                      135
<PAGE>

principle. Carrier1 International intends to take the position that $9.02 of the
$1,000 issue price of each dollar unit should be allocated to each associated
warrant and the remainder should be allocated to each dollar note. Carrier1
International also intends to take the position that [Euro]9.02 of the
[Euro]1,000 issue price of each Euro unit should be allocated to each associated
warrant and the remainder should be allocated to each Euro note. On the basis of
this allocation and Carrier1 International's best judgment, the amount of
original issue discount ("OID") will fall within the DE MINIMIS exception for
OID under the Code and will be treated as zero. Each holder will be bound by
such allocation for U.S. federal income tax purposes unless such holder
disclosed on a statement attached to its tax return for the taxable year that
includes the acquisition date of such unit that its allocation differs from that
of Carrier1 International. No assurance can be given that the Internal Revenue
Service (the "IRS") will accept Carrier1 International's allocation. If Carrier1
International's allocation were successfully challenged by the IRS, the issue
price, the amount of original issue discount accrued on the notes and gain or
loss on the sale or disposition of a note or warrant would be different from
that resulting under the allocation determined by Carrier1 International.


    NOTES


    TAXATION OF STATED INTEREST ON NOTES.  Stated interest on a note will be
includible in the income of a U.S. holder in accordance with such U.S. holder's
regular method of tax accounting. In the case of the Euro notes, a cash method
U.S. holder will translate stated interest into U.S. dollars at the spot
exchange rate in effect on the date such interest payment is received. In the
case of an accrual method U.S. holder of Euro notes, the amount of any interest
income accrued during any accrual period will generally be determined by
translating such accruals into U.S. dollars at the average exchange rate
applicable to the accrual period (or, with respect to an accrual period that
spans two taxable years, at the average exchange rate for the partial period
within the taxable year). Such a U.S. holder will additionally realize exchange
gain or loss with respect to any interest income accrued on the date that
payment in respect of such interest income is received (or on the date the note
is disposed of) in an amount equal to the difference between (x) the amount
determined by converting the amount of the payment received into U.S. dollars at
the spot exchange rate in effect on the date such payment is received and (y)
the amount of interest income accrued in respect of such payment according to
the rule set forth in the prior sentence. Any such exchange gain or loss will
generally be treated as ordinary income or loss. Notwithstanding the rules
described above, an accrual method U.S. holder may alternatively make an
election to apply a "spot accrual convention" that effectively allows such U.S.
holder to translate accrued interest into U.S. dollars at a single spot exchange
rate, as set forth in Treasury Regulations Section1.988-2(b)(2)(iii)(B). The
above election will apply to all other debt obligations held by the U.S. holder
and may not be changed without the consent of the IRS. The amount of interest
income earned by a U.S. holder as set forth in this paragraph will generally be
treated as "passive income" or, in the case of certain U.S. holders, "financial
services income", in either case from sources outside the United States, and any
foreign currency exchange gain or loss as set forth in this paragraph will
generally be treated as realized from sources within the United States.


    SALE, EXCHANGE OR REDEMPTION OF NOTES


    In general, unless a nonrecognition provision applies, the sale, exchange,
redemption (including pursuant to an offer by Carrier1 International) or other
disposition of a note will be a taxable event for U.S. federal income tax
purposes. In such event, a U.S. holder will recognize gain or loss equal to the
difference between (1) the amount of cash plus the fair market value of any
property received upon such sale, exchange, redemption or other taxable
disposition (except to the extent such cash or property is attributable to
accrued interest, which will be taxable as ordinary income) and (2) the U.S.
holder's adjusted tax basis in the note. Any such gain or loss with respect to a
dollar note should be capital gain or loss and will be long-term capital gain or
loss if such dollar note has been held by the U.S. holder for more than one year
at the time of such sale, exchange, redemption or other disposition. Such gain
generally will be treated as U.S. source and, under recently issued U.S.
Treasury Regulations, loss on such disposition would be allocated to reduce U.S.
source income, subject to applicable limitations. With respect to the sale,


                                      136
<PAGE>

exchange, retirement or repayment of a Euro note, the foreign currency amount
realized will be considered to be the payment of accrued but unpaid interest (on
which exchange gain or loss is recognized as described above) and as a payment
of principal. With respect to such payment of principal, exchange, gain or loss
is separately computed on the foreign currency amount of the purchase price that
is repaid to the extent that the rate of exchange on the date of retirement or
disposition differs from the rate of exchange on the date such Euro note was
acquired. Exchange gain or loss computed on accrued interest, and principal is
recognized, however, only to the extent of total gain or loss on the
transaction. In general, any such recognized exchange, gain or loss will be
treated as ordinary income realized from U.S. sources.


    SPECIAL INTEREST


    Because the notes provide for the payment of special interest in certain
circumstances described under "Description of the Notes--Registration Rights"
("Special Interest"), the notes will be subject to the Treasury Regulations that
apply to debt instruments that provide for one or more contingent payments.
Under those Regulations, however, a payment is not a contingent payment merely
because of a contingency that, as of the issue date, is either "remote" or
"incidental". Carrier1 International intends to take the position that, solely
for these purposes, the payment of Special Interest is a remote or incidental
contingency. Carrier1 International's determination that such payments are a
remote or incidental contingency for these purposes is binding on a U.S. holder,
unless such U.S. holder discloses in the proper manner to the Internal Revenue
Service that it is taking a different position. Prospective investors should
consult their tax advisers as to the tax considerations relating to the payment
of Special Interest, in particular in connection with the Treasury Regulations
relating to contingent payment instruments.


    TAXATION OF ADDITIONAL AMOUNTS


    In the event that Additional Amounts are paid in respect of withholding or
deduction for taxes imposed on payments on the notes (as described in
"Description of the Notes--Additional Amounts") such Additional Amounts will be
taxable to a U.S. holder as ordinary income at the time such amounts are accrued
or received, in accordance with the U.S. holder's method of accounting for U.S.
federal income tax purposes. The amount taxable to a U.S. holder also will
include all taxes withheld or deducted in respect thereof. Thus, a U.S. holder
may be required to report income in an amount greater than the cash it receives
in respect of payments on its notes. However, a U.S. holder may, subject to
certain limitations, be eligible to claim as a credit or deduction in respect of
such taxes for purposes of computing its U.S. federal income tax liability. The
rules relating to foreign tax credits are extremely complex, and U.S. holders
should consult their own tax advisors with regard to the availability of a
foreign tax credit and the application of the foreign tax credit to their
particular situation.


    TRANSACTIONS IN EURO


    Euro received as interest on, or on the sale, exchange or retirement of a
Euro note will have a tax basis equal to their U.S. dollar value at the time
such interest is received or at the time payment is received in consideration of
such sale, exchange or retirement. The amount of gain or loss recognized on a
sale or other disposition of such Euro will be equal to the differences between
(1) the amount of U.S. dollars, or the fair market value in U.S. dollars of the
other currency or property received in such sale or other disposition and (2)
the tax basis of such Euro.


                                      137
<PAGE>
    INFORMATION REPORTING AND BACKUP WITHHOLDING


    In general, information reporting requirements will apply to certain
payments of principal, interest and OID on a note and the proceeds of certain
sales of notes in respect of U.S. holders other than certain exempt persons
(such as corporations). A 31.0% backup withholding tax will apply to such
payments if the U.S. holder fails to provide a correct taxpayer identification
number or certification of exempt status or, with respect to certain payments,
the U.S. holder fails to report in full all interest income and the IRS notifies
the payor of such under-reporting.



    Any amounts withheld under the backup withholding rules will be allocated as
a credit against such U.S. holder's U.S. federal income tax liability and may
entitle such U.S. holder to a refund, provided the required information is
furnished to the IRS. Treasury regulations, generally effective for payment made
after December 31, 2000, modify certain of the certification requirements for
backup withholding. It is possible that Carrier1 International and other
withholding agents may request a new withholding exemption from holders in order
to qualify for continued exemption from backup withholding under Treasury
regulations when they become effective.


CERTAIN LUXEMBOURG TAX CONSIDERATIONS


    THE FOLLOWING DISCUSSION IS FOR GENERAL INFORMATION ONLY. EACH HOLDER IS
STRONGLY URGED TO CONSULT WITH ITS OWN TAX CONSULTANTS TO DETERMINE POSSIBLE
LUXEMBOURG TAX CONSEQUENCES OF AN EXCHANGE OR PURCHASE OF NOTES.



    The following summary outlines certain Luxembourg tax consequences to
persons who are nonresidents of Luxembourg and who do not have a permanent
establishment in Luxembourg ("Non-Resident Holders") with respect to the
ownership and disposition of notes.



    Under Luxembourg tax laws currently in effect, there is no withholding tax
on payment of principal, interest, nor on accrued but unpaid interest in respect
of the notes, nor is any Luxembourg withholding tax payable upon the redemption
of the notes.



    Non-Resident Holders of notes are not liable for Luxembourg income tax on
payments of principal or interest or upon redemption of, or on capital gains on
sale of, any notes.



    No stamp, value added, issue, registration, transfer or similar taxes or
duties will, under present Luxembourg law, be payable in Luxembourg by the
holders of the notes in connection with the issue of the notes.


                                      138
<PAGE>
                              PLAN OF DISTRIBUTION


    Each broker-dealer that receives new notes for its own account pursuant to
the exchange offer must acknowledge and represent that it will deliver a
prospectus in connection with any resale of such new notes. This prospectus, as
it may be amended or supplemented from time to time, may be used by certain
broker-dealers (as specified in the registration rights agreement) in connection
with resales of new notes received in exchange for old notes where such old
notes were acquired as a result of market-making activities or other trading
activities. Carrier1 has agreed that, for a period not to exceed 90 days after
the expiration date, it will furnish additional copies of this prospectus, as
amended or supplemented, to any such broker-dealer that reasonably requests such
documents for use in connection with any such resale. In addition, until
  , 1999, all dealers effecting transactions in the new notes may be required to
deliver a prospectus.



    Carrier1 will not receive any proceeds from any sale of new notes by
broker-dealers. New notes received by broker-dealers for their own account
pursuant to the exchange offer may be sold from time to time in one or more
transactions in the over-the-counter market, in negotiated transactions, through
the writing of options on the new notes or a combination of such methods of
resale, at market prices prevailing at the time of resale, at prices related to
such prevailing market prices or negotiated prices. Any such resale may be made
directly to purchasers or to or through brokers or dealers who may receive
compensation in the form of commissions or concessions from any such
broker-dealer and/or the purchasers of any such new notes. Any broker-dealer
that resells new notes that were received by it for its own account pursuant to
the exchange offer and any broker or dealer that participates in a distribution
of such new notes may be deemed to be an "underwriter" within the meaning of the
Securities Act and any profit on any such resale of new notes and any
commissions or concessions received by any such persons may be deemed to be
underwriting compensation under the Securities Act. Each letter of transmittal
states that, by acknowledging that it will deliver and by delivering a
prospectus, a broker-dealer will not be deemed to admit that it is an
"underwriter" within the meaning of the Securities Act.



    Carrier1 has agreed to pay certain expenses incident to the exchange offer,
and Carrier1 will indemnify the holders of the old notes against certain
liabilities.


                                 LEGAL MATTERS


    The validity of the new notes offered hereby will be passed upon for
Carrier1 by Debevoise & Plimpton, New York, New York, special New York counsel
to Carrier1 and certain other matters will be passed upon for Carrier1 by Bonn &
Schmitt, Luxembourg.


                                    EXPERTS

    The financial statements as of December 31, 1998 and for the period from
February 20, 1998 (date of inception) to December 31, 1998 included in this
prospectus have been audited by Deloitte & Touche Experta AG, independent
auditors, as stated in their report appearing herein, and are included in
reliance upon the report of such firm given upon their authority as experts in
accounting and auditing.

                                      139
<PAGE>
                   INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

<TABLE>
<CAPTION>
                                                                                                                PAGE
                                                                                                             -----------
<S>                                                                                                          <C>
INDEPENDENT AUDITORS' REPORT...............................................................................      F-2

CONSOLIDATED FINANCIAL STATEMENTS FOR THE PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31,
  1998:

  Consolidated Balance Sheet...............................................................................      F-3

  Consolidated Statement of Operations.....................................................................      F-4

  Consolidated Statement of Shareholders' Equity...........................................................      F-5

  Consolidated Statement of Cash Flows.....................................................................      F-6

  Notes to Consolidated Financial Statements...............................................................      F-7

UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS FOR THE THREE MONTHS ENDED MARCH 31, 1999 AND FOR THE PERIOD
  FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO MARCH 31, 1998:

  Consolidated Balance Sheet...............................................................................     F-19

  Consolidated Statement of Operations.....................................................................     F-20

  Consolidated Statement of Shareholders' Equity...........................................................     F-21

  Consolidated Statement of Cash Flows.....................................................................     F-22

  Notes to Consolidated Financial Statements...............................................................     F-23
</TABLE>

                                      F-1
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

                          INDEPENDENT AUDITORS' REPORT

To the Board of Directors and Shareholders of
Carrier1 International S.A.

    We have audited the accompanying consolidated balance sheet of Carrier1
International S.A. and subsidiaries (collectively, the "Company") as of December
31, 1998, and the related consolidated statements of operations, shareholders'
equity and cash flows for the period from February 20, 1998 (date of inception)
to December 31, 1998. These financial statements are the responsibility of the
Company's management. Our responsibility is to express an opinion on these
financial statements based on our audit.

    We conducted our audit in accordance with generally accepted auditing
standards in the United States of America. Those standards require that we plan
and perform the audit to obtain reasonable assurance about whether the financial
statements are free of material misstatement. An audit includes examining, on a
test basis, evidence supporting the amounts and disclosures in the financial
statements. An audit also includes assessing the accounting principles used and
significant estimates made by management, as well as evaluating the overall
financial statement presentation. We believe that our audit provides a
reasonable basis for our opinion.

    In our opinion, such consolidated financial statements present fairly, in
all material respects, the financial position of Carrier1 International S.A. and
subsidiaries as of December 31, 1998, and the results of its operations and its
cash flows for the period from February 20, 1998 (date of inception) to December
31, 1998 in conformity with generally accepted accounting principles in the
United States of America.

DELOITTE & TOUCHE EXPERTA AG

<TABLE>
<S>                                            <C>
/s/ DAVID WILSON                               /s/ JERRY M. MAYER
David Wilson                                   Jerry M. Mayer
</TABLE>

Erlenbach, Switzerland
March 17, 1999

                                      F-2
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

                           CONSOLIDATED BALANCE SHEET

                               DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

<TABLE>
<S>                                                                                  <C>
                                      ASSETS
CURRENT ASSETS:
  Cash and cash equivalents........................................................  $   4,184
  Restricted cash..................................................................      1,518
  Accounts receivables.............................................................      1,217
  Unbilled receivables.............................................................      1,645
  Other receivables................................................................      3,014
  Prepaid expenses and other current assets........................................      3,179
                                                                                     ---------
    Total current assets...........................................................     14,757
PROPERTY AND EQUIPMENT--Net (See Note 5)...........................................     31,091
INVESTMENT IN JOINT VENTURE (See Note 6)...........................................      4,675
OTHER ASSETS.......................................................................        911
                                                                                     ---------
TOTAL..............................................................................  $  51,434
                                                                                     ---------
                                                                                     ---------

                       LIABILITIES AND SHAREHOLDERS' EQUITY
CURRENT LIABILITIES:
  Trade accounts payable...........................................................  $  27,602
  Accrued liabilities..............................................................      4,643
                                                                                     ---------
    Total current liabilities......................................................     32,245
COMMITMENTS AND CONTINGENT LIABILITIES (See Note 7)
SHAREHOLDERS' EQUITY:
  Common stock, $2 par value, 30,000,000 shares authorized, 18,885,207 issued and
    outstanding (See Note 2).......................................................     37,770
  Accumulated deficit..............................................................    (19,235)
  Accumulated other comprehensive income...........................................        654
                                                                                     ---------
    Total shareholders' equity.....................................................     19,189
                                                                                     ---------
TOTAL..............................................................................  $  51,434
                                                                                     ---------
                                                                                     ---------
</TABLE>

                See notes to consolidated financial statements.

                                      F-3
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

                      CONSOLIDATED STATEMENT OF OPERATIONS

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)


<TABLE>
<S>                                                                                 <C>
REVENUES..........................................................................  $   2,792

OPERATING EXPENSES:
  Cost of services (exclusive of items shown separately below)....................     11,669
  Selling, general and administrative.............................................      8,977
  Depreciation and amortization...................................................      1,409
                                                                                    ---------
    Total operating expenses......................................................     22,055
                                                                                    ---------

LOSS FROM OPERATIONS..............................................................    (19,263)

OTHER INCOME (EXPENSE):
  Interest income (expense), net..................................................         81
  Other, net......................................................................        (53)
                                                                                    ---------
    Total other income (expense)..................................................         28
                                                                                    ---------

LOSS BEFORE INCOME TAX BENEFIT....................................................    (19,235)

INCOME TAX BENEFIT--Net of valuation allowance (See Note 9).......................         --
                                                                                    ---------
NET LOSS..........................................................................  $ (19,235)
                                                                                    ---------
                                                                                    ---------

EARNINGS (LOSS) PER SHARE:
  Net loss:
    Basic.........................................................................  $   (2.61)
                                                                                    ---------
                                                                                    ---------
    Diluted.......................................................................  $   (2.61)
                                                                                    ---------
                                                                                    ---------
</TABLE>


                See notes to consolidated financial statements.

                                      F-4
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

                 CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

<TABLE>
<CAPTION>
                                                                                           ACCUMULATED
                                                                                              OTHER
                                                                COMMON    ACCUMULATED     COMPREHENSIVE
                                                                 STOCK      DEFICIT          INCOME          TOTAL
                                                               ---------  ------------  -----------------  ----------
<S>                                                            <C>        <C>           <C>                <C>
Issuance of shares (18,885,207 shares).......................  $  37,770       --              --          $   37,770

Comprehensive income (loss):
  Net loss...................................................     --       $  (19,235)         --             (19,235)
  Other comprehensive income, net of tax:
    Currency translation adjustments.........................     --           --           $     654             654
                                                                                                           ----------
  Total comprehensive loss...................................                                                 (18,581)
                                                               ---------  ------------          -----      ----------
BALANCE--December 31, 1998...................................  $  37,770   $  (19,235)      $     654      $   19,189
                                                               ---------  ------------          -----      ----------
                                                               ---------  ------------          -----      ----------
</TABLE>

                See notes to consolidated financial statements.

                                      F-5
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

                      CONSOLIDATED STATEMENT OF CASH FLOWS

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

<TABLE>
<S>                                                                                 <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net loss........................................................................  $ (19,235)
  Adjustments to reconcile net loss to net cash used in operating activities:
    Depreciation and amortization.................................................      1,409
    Changes in operating assets and liabilities:
      Restricted cash.............................................................     (1,518)
      Receivables.................................................................     (5,838)
      Prepaid expenses and other current assets...................................     (3,165)
      Other assets................................................................       (898)
      Trade accounts payable and accrued liabilities..............................     14,804
                                                                                    ---------
        Net cash used in operating activities.....................................    (14,441)
                                                                                    ---------

CASH FLOWS FROM INVESTING ACTIVITIES:
  Purchases of property and equipment.............................................    (15,191)
  Investment in joint venture.....................................................     (4,675)
                                                                                    ---------
        Net cash used in investing activities.....................................    (19,866)
                                                                                    ---------

CASH FLOWS FROM FINANCING ACTIVITIES:
  Proceeds from issuance of common stock..........................................     37,770
                                                                                    ---------
        Net cash provided by financing activities.................................     37,770

EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS......................        721
                                                                                    ---------

NET INCREASE IN CASH AND CASH EQUIVALENTS.........................................      4,184

CASH AND CASH EQUIVALENTS:
  Beginning of period.............................................................         --
                                                                                    ---------
  End of period...................................................................  $   4,184
                                                                                    ---------
                                                                                    ---------

SUPPLEMENTAL DISCLOSURE OF NONCASH OPERATING AND INVESTING ACTIVITIES:
  As of December 31, 1998, the Company had purchased approximately $17,315 of
    equipment on open accounts payable.
</TABLE>

                See notes to consolidated financial statements.

                                      F-6
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

1. NATURE OF OPERATIONS

    Carrier1 International S.A., its subsidiaries in Europe and its subsidiary
in the United States ("Carrier1" or the "Company"), operate in the
telecommunications industry offering long distance voice and Internet Protocol
telecommunication services on a wholesale basis. The Company offers these
services primarily to competitive fixed-line operators, other carriers, wireless
operators, Internet service providers, resellers, and multi-national
corporations. The Company is a societe anonyme organized under the laws of the
Grand Duchy of Luxembourg and has adopted a fiscal year end of December 31.

    Since inception, the Company has financed its operations through equity
contributions. The expansion of the Company's business and network will require
significant capital to fund planned capital expenditures, working capital, cash
flow deficits and any debt service. As of December 31, 1998, the major investors
had contributed $37,770 in equity to fund start-up operations and have committed
to contribute an additional $22,230 in equity. In January 1999, the major
investors contributed the additional $22,230 in exchange for common stock of the
Company. In February 1999, the Company raised additional capital through a
private placement debt offering (see Note 13). If additional sources of
financing are required, the Company intends to pursue commercial bank
borrowings, equipment financing or accounts receivable financing, or the private
or public sale of equity or debt securities.

2. ORGANIZATION

    In February 1998, the investors of the Company purchased a shelf company
registered in the United Kingdom which was ultimately renamed Carrier1 UK
Limited ("UK"). Subsequently, UK formed subsidiaries in Switzerland, Germany,
the United States and the United Kingdom. In August 1998, Carrier1 International
S.A. ("SA") was formed. Subsequently, SA formed subsidiaries in France, the
Netherlands, Germany, Austria and Luxembourg. Both UK and SA were 99.995% owned
by Carrier One, LLC ("LLC"), a Delaware limited liability company. In December
1998, the Company reorganized the ownership structure of all of its
subsidiaries. The Company, in exchange for all of the outstanding shares of UK,
issued 15,365,207 shares of common stock to LLC.

    The effects of the reorganization have been accounted for as a
reorganization of entities under common control similar to a pooling of
interests. This reorganization has been reflected in the Company's consolidated
financial statements as if the post-reorganization structure had been in effect
since the date of inception since all of the entities are under common control.

3. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

USE OF ESTIMATES IN PREPARATION OF FINANCIAL STATEMENTS

    The preparation of financial statements in conformity with U.S. generally
accepted accounting principles requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities and
disclosure of contingent assets and liabilities at the date of the financial
statements and the reported amounts of revenue and expenses during the reporting
period. Actual results could differ from those estimates. Estimates are used
when accounting for such items as revenue,

                                      F-7
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

3. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
long-term customer contracts, allowances for uncollectable receivables,
investments, telecommunications expense, depreciation and amortization, employee
benefit plans and taxes.

PRINCIPLES OF CONSOLIDATION

    The consolidated financial statements of the Company are prepared in
accordance with generally accepted accounting principles in the United States.
The financial statements include the consolidated accounts of the Company with
all significant intercompany balances and transactions eliminated.

FOREIGN CURRENCY TRANSLATION


    The U.S. dollar is the Company's functional and reporting currency. The
financial statements of the Company's non-U.S. subsidiaries, where the local
currency is the functional currency, are translated into U.S. dollars using
exchange rates in effect at period end for assets and liabilities and average
exchange rates during each reporting period for results of operations.
Adjustments resulting from translation of financial statements are reflected as
a separate component of shareholders' equity.


    Transaction gains and losses that arise from exchange rate fluctuations on
transactions denominated in a currency other than the respective functional
currency are included in results of operations as incurred.

REVENUE

    The Company recognizes revenue on telecommunication services, generally
measured in terms of traffic minutes processed or transmission capacity provided
to customers, in the period that the service is provided. Revenue is presented
net of discounts.

COMPREHENSIVE INCOME

    Comprehensive income is the change in equity of a business enterprise during
a period from transactions and other events and circumstances from non-owner
sources. It includes all changes in equity for a period except those resulting
from investments by owners and distributions to owners. For the period from
February 20, 1998 (date of inception) to December 31, 1998, other comprehensive
income consisted of foreign currency translation adjustments.

EARNINGS PER SHARE

    Basic earnings per share is computed using the weighted average number of
shares outstanding during the period. Diluted earnings per share is computed by
including the stock options and stock subscriptions considered to be dilutive
common stock equivalents, unless deemed anti-dilutive.

CASH AND CASH EQUIVALENTS

    Cash equivalents consist primarily of interest bearing certificates of
deposit of well-rated European banks. The Company considers all highly-liquid
investments with a maturity of 90 days or less at the time of

                                      F-8
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

3. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
purchase to be cash equivalents. The carrying amount reported in the
accompanying balance sheets for cash equivalents approximates fair value due to
the short-term maturity of these instruments.

RESTRICTED CASH

    At December 31, 1998, $1,518 of cash was pledged as collateral on
outstanding letters of credit and guarantees to telecommunication companies that
provide refile services to the Company.

OTHER RECEIVABLES

    Other receivables consist primarily of value-added tax refund receivables at
December 31, 1998.

PROPERTY AND EQUIPMENT

    Property and equipment are stated at cost less accumulated depreciation.
Cost includes the charges received from the equipment and software suppliers for
turnkey installation and customization and network set-up costs. Depreciation is
recorded commencing with the first full month that the assets are in service.
The straight-line depreciation method is applied using the assets' estimated
useful lives as follows:

<TABLE>
<S>                                   <C>
Switching equipment, routers and
network management equipment
including related software            5 years

Computer and data center equipment    3 years

Furniture and fixtures                5 years

Leasehold improvements                Lesser of lease term or estimated
                                      useful life
</TABLE>


    Indefeasible right of use investments, which are treated as capital leases,
are amortized over their estimated useful lives, not to exceed 15 years even in
those cases where the right of use has been acquired for a longer period of
time. During the period from February 20, 1998 (date of inception) to December
31, 1998, the Company acquired a 25-year indefeasible right of use on a
transatlantic cable. This indefeasible right of use is being amortized over a
useful life of 15 years. Maintenance, repairs, and reengineering costs are
charged to expense as incurred.


LONG-LIVED ASSETS

    The Company reviews the carrying value of its long-lived assets for
impairment whenever events or changes in circumstances indicate that the
carrying value of these assets may not be recoverable. In the event that events
or circumstances indicate that the cost of any long-lived assets may be
impaired, an evaluation of recoverability would be performed. If an evaluation
is required, the estimated future undiscounted cash flows associated with the
asset would be compared to the asset's carrying amount to determine if a
write-down is required. The write-down would be measured as the difference
between the discounted estimated future operating cash flows from such asset and
the carrying value.

                                      F-9
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

3. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
PENSION PLANS

    The Company maintains various plans for providing employee pension benefits,
which conform to laws and practices in the countries concerned. Retirement
benefit plans are generally funded by contributions by both the employees and
the companies to independent entities that operate the retirement benefit
schemes. Where this is not the case, appropriate liabilities are recorded in the
financial statements. Currently, all of the Company's pension plans are defined
contribution plans.

TAXES

    Taxes are provided based on reported income and include taxes on capital as
well as non-recoverable tax withheld on dividends, management fees and royalties
received or paid. Such taxes are calculated in accordance with the tax
regulations in effect in each country. The Company provides for deferred taxes
using the comprehensive liability method. Provision is made in respect of all
temporary differences arising between the tax values of assets and liabilities
and their values in the consolidated financial statements. Provision is made
against deferred tax assets to the extent that it is more likely than not that
these will not be realized. Deferred tax balances are adjusted for subsequent
changes in tax rates or for new taxes imposed. Deferred tax liabilities are
included under provisions. Non-recoverable withholding taxes are only accrued if
distribution by subsidiary companies is probable.

STOCK-BASED COMPENSATION PLANS

    The Company records compensation expense for its stock-based compensation
plans in accordance with the intrinsic value method prescribed by APB 25,
"Accounting for Stock Issued to Employees." Intrinsic value is the amount by
which the estimated market value of the underlying stock exceeds the exercise
price of the stock option on the measurement date, generally the date of grant.

FAIR VALUE OF FINANCIAL INSTRUMENTS

    At December 31, 1998, the carrying amounts of the Company's financial
instruments approximate their fair value.

NEW ACCOUNTING PRONOUNCEMENT

    In June 1998, the Financial Accounting Standards Board issued Statement of
Financial Accounting Standards ("SFAS") No. 133, "Accounting for Derivative
Instruments and Hedging Activities." This statement establishes accounting and
reporting standards for derivative instruments embedded in other contracts
(collectively referred to as derivatives) and for hedging activities. It
requires that an entity recognize all derivatives as either assets or
liabilities in the statement of financial position and measure those instruments
at fair value. If certain conditions are met, a derivative may be specifically
designated as (a) a hedge of the exposure to changes in the fair value of a
recognized asset or liability or an unrecognized firm commitment, (b) a hedge of
the exposure to variable cash flows of a forecasted transaction, or (c) a hedge
of the foreign currency exposure of a net investment in a foreign operation, an
unrecognized firm commitment, an available-for-sale security, or a
foreign-currency-denominated forecasted transaction. This

                                      F-10
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

3. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
standard is effective for the Company's fiscal year ending December 31, 2000.
Management has not yet completed its analysis of this new accounting standard
and, therefore, has not determined whether this standard will have a material
effect on the Company's financial statements.

4. EARNINGS PER SHARE

    The following details the earnings per share calculations for the period
from February 20, 1998 (date of inception) to December 31, 1998 (in thousands of
U.S. dollars, except per share information):

<TABLE>
<S>                                                               <C>
Loss from operations............................................  $ (19,263)
                                                                  ---------
                                                                  ---------
Net loss........................................................  $ (19,235)
                                                                  ---------
                                                                  ---------
Total number of shares used to compute basic earnings
  (loss) per share..............................................  7,367,000
                                                                  ---------
                                                                  ---------
Loss from operations:
  Basic loss per share..........................................  $   (2.61)
                                                                  ---------
                                                                  ---------
  Diluted loss per share........................................  $   (2.61)
                                                                  ---------
                                                                  ---------
Net loss:
  Basic loss per share..........................................  $   (2.61)
                                                                  ---------
                                                                  ---------
  Diluted loss per share........................................  $   (2.61)
                                                                  ---------
                                                                  ---------
</TABLE>

    Potential dilutive securities have been excluded from the computation for
the period from February 20, 1998 (date of inception) to December 31, 1998 as
their effect is antidilutive. Had the Company been in a net income position for
the period from February 20, 1998 (date of inception) to December 31, 1998,
diluted earnings per share would have included an additional 2,822,000 shares
related to outstanding stock options and stock subscriptions (determined using
the treasury stock method at the estimated average market value).

                                      F-11
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

5. PROPERTY AND EQUIPMENT

    Property and equipment at December 31, 1998 consist of the following:

<TABLE>
<S>                                                               <C>
Network equipment...............................................   $  14,613
Indefeasible right of use investments...........................      11,106
Leasehold improvements..........................................       1,712
Furniture, fixtures and office equipment........................         709
Construction in progress........................................       4,353
                                                                  -----------
                                                                      32,493

Less: accumulated depreciation and amortization.................      (1,402)
                                                                  -----------
  Property and equipment, net...................................   $  31,091
                                                                  -----------
                                                                  -----------
</TABLE>


    At December 31, 1998, network equipment totaling $13,565, which is owned by
the Company and has been accrued as trade accounts payable, is expected to be
pledged as collateral under a product financing arrangement with a vendor. The
Company is currently negotiating the terms and conditions of such financing
arrangement with the vendor, which is obligated to provide financing under the
terms of the related turnkey purchase agreement.


6. INVESTMENT IN JOINT VENTURE

    The Company entered into a binding letter of intent dated August 20, 1998
(the "LOI") with affiliates of Viatel, Inc. ("Viatel") and Metromedia Fiber
Network, Inc. ("Metromedia") which sets forth the principal terms upon which the
parties will build and own a telecommunications network in Germany (the "German
Network"). Under the LOI, the parties have agreed to form a company (the
"Developer") to act as their agent to arrange construction of the German
Network. The Developer will be owned 50.01%, 24.995%, and 24.995% by Viatel, the
Company and Metromedia, respectively. The Developer will be responsible for the
development, design, construction and supervision of the German Network and will
also provide other services related to the German Network.

    The parties are currently in negotiations with respect to the legal
structure of the Developer and the definitive project terms. Until such
development agreement has been negotiated and executed by the parties, Viatel
will provide such services as the Developer is obligated to provide under the
LOI. Each of the parties has contributed $4.05 million for incremental costs,
and their pro-rata share of $2.5 million for pre-development costs. Each party
is obligated to provide the Developer with a $75 million letter of credit,
conditional upon the ability of each of the Company and Metromedia to raise at
least $75 million through financing or equity. Failure by any party to do so
will terminate the LOI with respect to such party, and any or all of the parties
that have not so defaulted may, at their option, assume the rights and
obligations of the defaulting party and continue with the construction of the
German Network. If neither remaining party assumes the rights and obligations of
the defaulting party, the LOI is terminated. Under the terms of the LOI, Viatel
is entitled to receive a developer's fee of 3% of certain construction costs
associated with the German Network.

                                      F-12
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

6. INVESTMENT IN JOINT VENTURE (CONTINUED)
    Upon completion of the German Network, each party will own its own cable
subduct and access points. In addition, to the extent possible, each party will
have its own divisible and transferable rights in all permits, easements, rights
of way and other third party approvals. In the event the agreement is
terminated, each party (other than a defaulting party) is entitled to maintain
its ownership interest in any intellectual property rights, technology, plans,
permits and approvals (to the extent such permits and approvals are issued in
the name of such party) and other intangible property, as well as in any actual
construction completed and materials ordered.

    On February 19, 1999, the parties executed a development agreement. In
accordance with the development agreement, the Company provided a 109.5 million
Deutsche Mark letter of credit (approximately $64.8 million) to the Developer to
fund the Company's share of construction costs (see Note 13).

    The Company currently estimates that its share of the development costs of
the German Network will be up to approximately $82 million, including the fiber
deployed, which is expected to be incurred over the next 15 months.

7. COMMITMENTS AND CONTINGENCIES

LEASES

    The Company leases certain network capacity, office space, equipment,
vehicles, and operating facilities under noncancellable operating leases.
Certain leases contain renewal options and many leases for office space require
the Company to pay additional amounts for operating and maintenance costs. As of
December 31, 1998, future minimum lease payments under operating leases with
remaining terms in excess of one year are as follows:

<TABLE>
<S>                                                               <C>
1999............................................................   $  11,393
2000............................................................       2,863
2001............................................................       2,637
2002............................................................       2,558
2003............................................................       1,235
Thereafter......................................................         692
                                                                  -----------
  Total minimum lease payments..................................   $  21,378
                                                                  -----------
                                                                  -----------
</TABLE>

    Total rental expense under operating leases was $5,171 during the period
from February 20, 1998 (date of inception) to December 31, 1998.

PURCHASE COMMITMENTS

    During the period from February 20, 1998 (date of inception) to December 31,
1998, the Company entered into an agreement to purchase a Multiple Investment
Unit ("MIU") that gives the Company rights to a portion of a trans-Atlantic
cable scheduled for completion in early 2000. Currently, the Company

                                      F-13
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

7. COMMITMENTS AND CONTINGENCIES (CONTINUED)
estimates its remaining share of development and construction costs to be
$11,262. The Company has also entered into various contracts with vendors to
provide network set-up and maintenance services. Based on the Company's current
network development plans, such amounts are expected to be paid as follows:

<TABLE>
<CAPTION>
                                                                           NETWORK
                        IN THOUSANDS                              MIU     SERVICES     TOTAL
- -------------------------------------------------------------  ---------  ---------  ---------
<S>                                                            <C>        <C>        <C>
1999.........................................................  $   3,155  $   9,050  $  12,205
2000.........................................................      7,155      9,360     16,515
2001.........................................................        952                   952
                                                               ---------  ---------  ---------
                                                               $  11,262  $  18,410  $  29,672
                                                               ---------  ---------  ---------
                                                               ---------  ---------  ---------
</TABLE>

8. INCENTIVE COMPENSATION PLANS


    In February 1998, the employee stock option plan (the "Stock Option Plan")
was adopted. This plan provides for the issuance of options to purchase Class A
or Class B shares of LLC, based on certain criteria as defined in the plan
document. The aggregate number of options to be issued under the Stock Option
Plan is the lesser of 4,444,444 options or 11.1% of the number of shares
purchased by the current owners of LLC. The per-share exercise price for the
options may not be less than $1 per share. Options vest over a period of five
years and expire if not exercised within 10 years of the grant. In connection
with the creation of the Stock Option Plan, employees were required to agree to
reduce the percentage of the bonus to which they are eligible under the
Company's cash bonus plan (the "Cash Bonus Plan"). The Company intends to issue
such options to eligible employees in 1999. As of December 31, 1998, the Company
had granted options to acquire 4,044,442 Class A shares for a purchase price of
$1 per share to certain members of management. As a result of the reorganization
of the Company in December 1998, the Company intends to create a new option plan
so that employees will be granted options from the Company rather than LLC. The
Company intends to have LLC cancel options granted under the Stock Option Plan
and will grant replacement options with the same economic terms under the new
plan. (See Note 13).


    As required by Statement of Financial Accounting Standards No. 123,
"Accounting for Stock-Based Compensation" ("SFAS 123"), the Company has
determined the pro-forma information as if the Company had accounted for stock
options under the fair value method of SFAS 123. The weighted-average fair value
of options granted during the period was $0.15 per option. The fair value of
option grants is estimated on the date of grant using the minimum value
option-pricing model, as allowed under SFAS 123 for nonpublic companies, for
pro-forma footnote purposes with the following assumptions used: dividend yield
of 0%, risk-free interest rate of 5.53%, and expected option life of 5 years.

                                      F-14
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

8. INCENTIVE COMPENSATION PLANS (CONTINUED)
    The tax-effected pro-forma effect of these options would be as follows:

<TABLE>
<S>                                                                 <C>
Net loss, as reported.............................................  $ (19,235)
Estimated fair value of options granted, net of tax...............       (226)
                                                                    ---------
Net loss, adjusted................................................  $ (19,461)
                                                                    ---------
                                                                    ---------
Adjusted net loss per share--basic basis..........................  $   (2.64)
                                                                    ---------
                                                                    ---------
</TABLE>

    In March 1998, the Company established the Cash Bonus Plan to provide
incentive compensation to certain officers and employees. Individuals are
eligible to receive an annual cash bonus ranging from 10% to 25% of their annual
salary based on the terms of their employment agreement. Bonuses are payable at
the discretion of the Board of Directors based upon the Company achieving
specific goals.


    Employees were also entitled to subscribe to purchase shares (the "Stock
Purchase Plan") in LLC at the price of $1 per Class A share up to a maximum
investment of approximately $68 per employee. The purchase offer was valid until
September 1, 1998 with payment due before October 1, 1998. Under the Stock
Purchase Plan, certain employees committed to purchase approximately 1,424,000
Class A shares with an aggregate value of approximately $1,424. Management has
determined that no compensation expense is required to be recognized in
connection with this plan since the estimated market value of the stock was less
than the price paid by employees. As a result of the reorganization of the
Company in December 1998, the Company has amended the Stock Purchase Plan so
that employees will be issued shares of common stock of the Company rather than
shares of LLC. In 1999, the Company collected the amounts due from employees
under the Stock Purchase Plan and expects to issue the related shares in the
second quarter of 1999.


9. INCOME TAXES

    The income tax benefit for the period from February 20, 1998 (date of
inception) to December 31, 1998 consists of the following:

<TABLE>
<S>                                                               <C>
Current.........................................................   $  --
Deferred........................................................       5,378
                                                                  -----------
                                                                       5,378
Valuation allowance.............................................      (5,378)
                                                                  -----------
Total...........................................................   $  --
                                                                  -----------
                                                                  -----------
</TABLE>

    The Company has tax loss carryforwards of approximately $5,378 at December
31, 1998. The ability of the Company to fully realize deferred tax assets
related to these tax loss carryforwards in future years is contingent upon its
success in generating sufficient levels of taxable income before the statutory
expiration periods for utilizing such net operating losses lapses. Net operating
losses expire as follows: 2003--$149; 2005--$3,245; 2013--$318. Net operating
losses totaling $1,666 do not expire. Due to its limited history,

                                      F-15
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

9. INCOME TAXES (CONTINUED)
the Company was unable to conclude that realization of such deferred tax assets
in the near future was more likely than not. Accordingly, a valuation allowance
was recorded to offset the full amount of such assets.

    Deferred income tax assets result primarily from net operating loss
carryforwards. Other components of deferred income tax assets and liabilities
are not significant as of December 31, 1998.

10. RELATED PARTY TRANSACTIONS

    During the period from February 20, 1998 (date of inception) to December 31,
1998, the Company reimbursed certain companies, which are shareholders in LLC,
for expenses incurred in connection with the formation of the Company and the
negotiation of certain agreements entered into by the Company. Such
reimbursements totaled $339 and were expensed as selling, general and
administrative expenses.

    The Company has entered into a transmission peering arrangement with an
entity that is 21% beneficially owned by a combination of Providence Equity
Partners L.P., the majority unitholder of LLC, and Providence Equity Partners II
L.P., another unitholder of LLC. Under the terms of the agreement, the parties
agree to carry certain levels of each other's traffic on their network without
charge for one year. This agreement is automatically renewable unless it is
terminated by either party with appropriate notice as required by the agreement.

11. EMPLOYEE BENEFIT PLANS

    The Company contributes to defined contribution pension plans in accordance
with the laws and practices of the countries in which it operates. During the
period from February 20, 1998 (date of inception) to December 31, 1998, the
Company recorded pension expense totaling $267.

12. SEGMENT AND RELATED INFORMATION

    SFAS No. 131, "Disclosures about Segments of an Enterprise and Related
Information," requires the Company to disclose certain information related to
segments and geographic areas in which the Company operates and its major
customers.

SEGMENT INFORMATION


    The Company has identified two reportable operating segments as defined in
SFAS No. 131: voice services and Internet Protocol data services. The voice
services segment provides long distance voice telecommunications services to
competitive fixed-line operators, other carriers, wireless operators, resellers
and multi-national corporations. The data services segment provides data
telecommunications services to Internet service providers.


    The Company's reportable segments are strategic business units that offer
different products and services. They are managed separately because each
business requires different technology and marketing strategies.

                                      F-16
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

12. SEGMENT AND RELATED INFORMATION (CONTINUED)
    The accounting policies of the segments are the same as those described in
the summary of significant accounting policies. The Company evaluates
performance of segments based on its fixed cost contribution, which is defined
as segment revenues less direct variable costs incurred by the segment. Fixed
cost contribution is a non-GAAP measure of financial performance. Shared costs
and assets are not allocated to the segments. There were no intersegment
transactions during the period from February 20, 1998 (date of inception) to
December 31, 1998.


    Summarized financial information concerning the Company's reportable
segments as of December 31, 1998 and for the period from February 20, 1998 (date
of inception) to December 31, 1998 is shown in the following table. The "Other"
column includes unallocated shared network and corporate related assets which
are all assets other than network equipment that has been identified as relating
to a specific segment.



<TABLE>
<CAPTION>
                                                    VOICE       DATA
                                                  SERVICES    SERVICES      OTHER    CONSOLIDATED
                                                  ---------  -----------  ---------  ------------
<S>                                               <C>        <C>          <C>        <C>
Revenues........................................  $   2,735   $      57               $    2,792
Fixed cost contribution.........................         61          57                      118
Identifiable assets.............................      9,599       1,801      40,034       51,434
Depreciation and amortization...................        483         125         801        1,409
Capital expenditures............................     10,082       1,926      25,160       37,168
</TABLE>



    The following table reconciles the fixed cost contribution for reportable
segments to the loss before income tax benefit for the period from February 20,
1998 (date of inception) to December 31, 1998:



<TABLE>
<CAPTION>
<S>                                                                                 <C>
Total fixed cost contribution for reportable segments.............................  $      118
Unallocated amounts
  Unallocated cost of services....................................................      (8,995)
  Selling, general and administrative expenses....................................      (8,977)
  Depreciation and amortization...................................................      (1,409)
  Total other income (expense)....................................................          28
                                                                                    ----------
Loss before income tax benefit....................................................  $  (19,235)
                                                                                    ----------
                                                                                    ----------
</TABLE>


GEOGRAPHIC INFORMATION

    The following table also provides detail of the Company's revenues for the
period from February 20, 1998 (date of inception) to December 31, 1998 and
long-lived assets as of December 31, 1998 on a geographic basis. Revenues have
been allocated based on the location of the customer. Indefeasible right

                                      F-17
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

12. SEGMENT AND RELATED INFORMATION (CONTINUED)
of use investments are included based on the entity which owns the investment.
The Company did not earn any revenues in its country of domicile, Luxembourg.

<TABLE>
<CAPTION>
                                                                                      LONG-LIVED
                                                                          REVENUES      ASSETS
                                                                         -----------  -----------
<S>                                                                      <C>          <C>
Germany................................................................   $     878    $  10,369
Switzerland............................................................         108       14,186
United Kingdom.........................................................       1,768        7,399
United States..........................................................                    3,006
Other countries........................................................          38        1,717
                                                                         -----------  -----------
                                                                          $   2,792    $  36,677
                                                                         -----------  -----------
                                                                         -----------  -----------
</TABLE>

MAJOR CUSTOMERS

    During the period from February 20, 1998 (date of inception) to December 31,
1998, the Company earned 69% of its revenues from three major customers as
follows:

<TABLE>
<CAPTION>
                                                                                         % OF
CUSTOMER                                                                               REVENUES
- -----------------------------------------------------------------------------------  -------------
<S>                                                                                  <C>
Interroute Telecommunications (UK) Limited.........................................           46%
WorldCom Telecommunications Services GmbH..........................................           13%
Star Telecommunications Deutschland GmbH...........................................           10%
                                                                                              --
                                                                                              69%
                                                                                              --
                                                                                              --
</TABLE>

13. SUBSEQUENT EVENTS

SHAREHOLDERS' EQUITY

    On January 15, 1999, the Board of the Company adopted the 1999 Share Option
Plan (the "1999 Option Plan"), under which Carrier1 International SA and related
companies of the consolidated Carrier1 group (the "Related Corporations") may
grant to any employee of the Company or Related Corporations options in equity
securities (the "Options") issued by the Company. The 1999 Option Plan is
administered by the Board and may be administered by a committee appointed by
the Board, and authorizes the Board or such committee to issue Options in such
forms and on such terms as determined by the Board or such committee. The Board
or such committee may determine the number of Options to grant, provided that
the number of shares of the Company (the "Shares") issued pursuant to the 1999
Option Plan is no greater than the lesser of (a) 2,222,222 Shares and (b) the
number of Shares representing 11.1% of the Shares held by purchasers purchasing
shares pursuant to a securities purchase agreement dated as of December 30,
1998. The per-share exercise price for the Options may not be less than $2.
Options granted under the 1999 Option Plan vest in five equal annual
installments beginning on the first anniversary of the grant of such Options.
Options expire if not exercised within 10 years of the grant, or on an earlier
date as specified by the Board or the committee. If the employment of a
participant is terminated for any reason, all unvested Options immediately
expire and vested Options must be exercised within a certain period of time as

                                      F-18
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

     PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

13. SUBSEQUENT EVENTS (CONTINUED)
specified by the plan document. The Company expects to cancel the options
granted under the 1998 Stock Option Plan and issue replacement options under the
1999 Option Plan by May 31, 1999.

    On February 10, 1999, the Company increased its authorized number of shares
to 55,000,000.

LONG-TERM DEBT

    On February 19, 1999, the Company issued $165 million and [Euro]85 million
of 13 1/4% senior notes (the "Notes") with detachable warrants with a scheduled
maturity of February 2009. Each Dollar warrant is initially exercisable to
purchase 6.71013 shares of common stock and each Euro warrant is initially
exercisable to purchase 7.53614 shares of common stock. Holders will be able to
exercise the warrants at a per share price equal to the greater of $2.00 per
share and the minimum par value required by Luxembourg law (currently 50
Luxembourg francs), subject to adjustment.

    The Company has the right to redeem any of the Notes beginning on February
15, 2004. The initial redemption price is 106.625% of their principal amount,
plus accrued interest. The redemption price will decline each year after 2004
and will be 100% of their principal amount, plus accrued interest, beginning on
February 15, 2007. In addition, before February 15, 2002, the Company may redeem
up to 35% of the aggregate amount of either series of Notes with the proceeds of
sales of its capital stock at 113.25% of their principal amount. The Company may
make such redemption only if after any such redemption, an amount equal to at
least 65% of the aggregate principal amount of such Notes originally issued
remains outstanding.

    The Notes contain covenants that restrict the Company's ability to enter
into certain transactions including, but not limited to, incurring additional
indebtedness, creating liens, paying dividends, redeeming capital stock, selling
assets, issuing or selling stock of restricted subsidiaries, or effecting a
consolidation or merger.

    The Company is obligated to use its best efforts to cause the Notes to
generally be freely transferable under the Securities Act of 1933 no later than
August 19, 1999. If this requirement is not met, then the interest on the Notes
will increase by 0.5% per annum until the Notes are generally freely
transferable.

COMMITMENTS

    On February 2, 1999, the Company entered into a letter of intent for a lease
for network fiber, which requires monthly payments of $274, including operating
and maintenance costs, for 36 months, after which the Company will obtain a
15-year IRU for the leased fiber at no additional charge. The Company will be
required to pay an annual operating and maintenance fee of $250 for the term of
the indefeasible right of use.

    On February 18, 1999, the Company entered into an agreement to purchase
fiber optic cable for the German Network during 1999 for $20,286, plus
value-added tax. The seller will either provide financing for the entire amount
of the purchase with the contract value to be repaid over three years in equal
annual installments beginning on December 31, 2001 together with interest, or
will allow the Company to make payment in full by December 31, 2001 without
interest. The loan, if provided, will bear interest at the U.S. dollar Libor
rate plus 4% per annum. If a loan is not provided, the seller is obligated to
provide certain additional equipment to the Company without charge.

                                      F-19
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

                          CONSOLIDATED BALANCE SHEETS

                      MARCH 31, 1999 AND DECEMBER 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)


<TABLE>
<CAPTION>
                                                                                                     DECEMBER 31,
                                                                                                        1998*
                                                                                         MARCH 31,   ------------
                                                                                           1999
                                                                                        -----------
                                                                                        (UNAUDITED)
<S>                                                                                     <C>          <C>
ASSETS
CURRENT ASSETS:
  Cash and cash equivalents...........................................................   $ 107,960    $    4,184
  Restricted cash.....................................................................       1,446         1,518
  Restricted investments held in escrow (See Notes 5 and 6)...........................      98,180            --
  Accounts receivables................................................................       6,583         1,217
  Unbilled receivables................................................................       5,829         1,645
  Other receivables...................................................................       5,301         3,014
  Prepaid expenses and other current assets...........................................       4,508         3,179
                                                                                        -----------  ------------
    Total current assets..............................................................     229,807        14,757
PROPERTY AND EQUIPMENT--Net...........................................................      41,546        31,091
INVESTMENT IN JOINT VENTURE...........................................................       4,675         4,675
RESTRICTED INVESTMENTS HELD IN ESCROW (See Note 6)....................................      44,854            --
OTHER ASSETS..........................................................................       8,895           911
                                                                                        -----------  ------------
TOTAL.................................................................................   $ 329,777    $   51,434
                                                                                        -----------  ------------
                                                                                        -----------  ------------

LIABILITIES AND SHAREHOLDERS' EQUITY
CURRENT LIABILITIES:
  Trade accounts payable..............................................................   $  36,015    $   27,602
  Accrued liabilities.................................................................      15,279         4,643
                                                                                        -----------  ------------
    Total current liabilities.........................................................      51,294        32,245
LONG-TERM DEBT (Net of discount of $2,269) (See Note 6)...............................     249,608            --
COMMITMENTS AND CONTINGENT LIABILITIES
SHAREHOLDERS' EQUITY:
  Common stock, $2 par value, 30,000,000 shares authorized, 30,000,000 and 18,885,207
    issued and outstanding at March 31, 1999 and December 31, 1998, respectively......      60,000        37,770
  Additional paid-in capital (See Note 8).............................................       2,304            --
  Accumulated deficit.................................................................     (34,265)      (19,235)
  Accumulated other comprehensive income..............................................         836           654
                                                                                        -----------  ------------
    Total shareholders' equity........................................................      28,875        19,189
                                                                                        -----------  ------------
TOTAL.................................................................................   $ 329,777    $   51,434
                                                                                        -----------  ------------
                                                                                        -----------  ------------
</TABLE>


*   Derived from audited consolidated financial statements.

           See notes to unaudited consolidated financial statements.

                                      F-20
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

                 UNAUDITED CONSOLIDATED STATEMENT OF OPERATIONS

                     THREE MONTHS ENDED MARCH 31, 1999 AND
      PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO MARCH 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)


<TABLE>
<CAPTION>
                                                                                                         PERIOD
                                                                                            THREE         FROM
                                                                                            MONTHS    FEBRUARY 20,
                                                                                            ENDED       1998 TO
                                                                                          MARCH 31,    MARCH 31,
                                                                                             1999         1998
                                                                                          ----------  ------------
<S>                                                                                       <C>         <C>
REVENUES................................................................................  $   12,293   $       --

OPERATING EXPENSES:
  Cost of services (exclusive of items shown separately below)..........................      17,015           --
  Selling, general and administrative...................................................       3,318          157
  Depreciation and amortization.........................................................       1,336           --
                                                                                          ----------
    Total operating expenses............................................................      21,669          157
                                                                                          ----------  ------------

LOSS FROM OPERATIONS....................................................................      (9,376)        (157)

OTHER INCOME (EXPENSE):
  Interest expense......................................................................      (4,205)
  Interest income.......................................................................         979           --
  Currency exchange loss, net...........................................................      (2,428)          --
                                                                                          ----------  ------------
    Total other income (expense)........................................................      (5,654)          --
                                                                                          ----------  ------------

LOSS BEFORE INCOME TAX BENEFIT..........................................................     (15,030)        (157)

INCOME TAX BENEFIT--Net of valuation allowance..........................................          --           --
                                                                                          ----------  ------------
NET LOSS................................................................................  $  (15,030)  $     (157)
                                                                                          ----------  ------------
                                                                                          ----------  ------------

EARNINGS (LOSS) PER SHARE:

  Net loss:
    Basic...............................................................................  $    (0.53)  $    (1.50)
                                                                                          ----------  ------------
                                                                                          ----------  ------------
    Diluted.............................................................................  $    (0.53)  $    (1.50)
                                                                                          ----------  ------------
                                                                                          ----------  ------------
</TABLE>


           See notes to unaudited consolidated financial statements.

                                      F-21
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES


            UNAUDITED CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY


                       THREE MONTHS ENDED MARCH 31, 1999

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)


<TABLE>
<CAPTION>
                                                                                           ACCUMULATED
                                                             ADDITIONAL                       OTHER
                                                  COMMON      PAID-IN-    ACCUMULATED     COMPREHENSIVE
                                                   STOCK       CAPITAL      DEFICIT          INCOME          TOTAL
                                                -----------  -----------  ------------  -----------------  ----------
<S>                                             <C>          <C>          <C>           <C>                <C>
BALANCE--December 31, 1998....................  $    37,770                $  (19,235)      $     654      $   19,189
Issuance of shares (11,114,793 shares)........       22,230                                                    22,230
Issuance of warrants..........................                $   2,304                                         2,304

Comprehensive income (loss):
  Net loss....................................                                (15,030)                        (15,030)
  Other comprehensive income, net of tax:
    Currency translation adjustments..........                                                    182             182
                                                                                                           ----------
  Total comprehensive loss....................                                                                (14,848)
                                                -----------  -----------  ------------          -----      ----------
BALANCE--March 31, 1999.......................  $    60,000   $   2,304    $  (34,265)      $     836      $   28,875
                                                -----------  -----------  ------------          -----      ----------
                                                -----------  -----------  ------------          -----      ----------
</TABLE>


           See notes to unaudited consolidated financial statements.

                                      F-22
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

                UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS

                     THREE MONTHS ENDED MARCH 31, 1999 AND
      PERIOD FROM FEBRUARY 20, 1998 (DATE OF INCEPTION) TO MARCH 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)


<TABLE>
<CAPTION>
                                                                                                         PERIOD
                                                                                            THREE         FROM
                                                                                           MONTHS     FEBRUARY 20,
                                                                                            ENDED        1998 TO
                                                                                          MARCH 31,     MARCH 31,
                                                                                            1999          1998
                                                                                         -----------  -------------
<S>                                                                                      <C>          <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net loss.............................................................................  $   (15,030)        (157)
  Adjustments to reconcile net loss to net cash used in operating activities:
    Depreciation and amortization......................................................        1,336           --
    Changes in operating assets and liabilities:
      Restricted cash..................................................................           71           --
      Receivables......................................................................      (12,077)          --
      Prepaid expenses and other current assets........................................         (677)          (1)
      Other assets.....................................................................       (8,515)          --
      Trade accounts payable and accrued liabilities...................................       15,982           44
                                                                                         -----------        -----
        Net cash used in operating activities..........................................      (18,910)        (114)
                                                                                         -----------        -----

CASH FLOWS FROM INVESTING ACTIVITIES:
  Purchases of property and equipment..................................................       (9,688)          --
  Purchases of restricted investments held in escrow...................................     (143,034)          --
                                                                                         -----------        -----
        Net cash used in investing activities..........................................     (152,722)          --
                                                                                         -----------        -----

CASH FLOWS FROM FINANCING ACTIVITIES:
  Proceeds from issuance of short-term debt............................................                        66
  Proceeds from issuance of long-term debt.............................................      249,608           --
  Proceeds from issuance of common stock...............................................       24,533          177
                                                                                         -----------        -----
        Net cash provided by financing activities......................................      274,141          243

EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS...........................        1,267          (10)
                                                                                         -----------        -----

NET INCREASE IN CASH AND CASH EQUIVALENTS..............................................      103,776          119

CASH AND CASH EQUIVALENTS:
  Beginning of period..................................................................        4,184
                                                                                         -----------        -----
  End of period........................................................................  $   107,960    $     119
                                                                                         -----------        -----
                                                                                         -----------        -----

SUPPLEMENTAL DISCLOSURE OF NONCASH OPERATING AND INVESTING ACTIVITIES:
  At March 31, 1999 and December 31, 1998, the Company had purchased approximately
    $21,713 and $17,315, respectively, of equipment on open accounts payable.
</TABLE>


           See notes to unaudited consolidated financial statements.

                                      F-23
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

              NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

      THREE MONTHS ENDED MARCH 31, 1999 AND PERIOD FROM FEBRUARY 20, 1998
                     (DATE OF INCEPTION) TO MARCH 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

1. NATURE OF OPERATIONS

    Carrier1 International S.A., its subsidiaries in Europe and its subsidiary
in the United States ("Carrier1" or the "Company"), operate in the
telecommunications industry offering long distance voice and Internet Protocol
telecommunication services on a wholesale basis. The Company offers these
services primarily to competitive fixed-line operators, other carriers, wireless
operators, Internet service providers, resellers, and multi-national
corporations. The Company is a societe anonyme organized under the laws of the
Grand Duchy of Luxembourg and has adopted a fiscal year end of December 31.

2. UNAUDITED FINANCIAL INFORMATION

    The financial information included herein is unaudited; however, the
information reflects all adjustments (consisting solely of normal recurring
adjustments) that are, in the opinion of management, necessary for a fair
presentation of the Company's financial position and results of operations and
cash flows for the interim periods presented. The results of operations for the
three months ended March 31, 1999 are not necessarily indicative of the results
to be expected for the full year.

3. EARNINGS PER SHARE

    The following details the earnings per share calculations for the three
months ended March 31, 1999 and for the period from February 20, 1998 (date of
inception) to March 31, 1998 (in thousands of U.S. dollars, except share
information):

<TABLE>
<CAPTION>
                                                                                  PERIOD FROM
                                                                   THREE MONTHS   FEBRUARY 20,
                                                                       ENDED        1998 TO
                                                                     MARCH 31,     MARCH 31,
                                                                       1999           1998
                                                                   -------------  ------------
<S>                                                                <C>            <C>
Loss from operations.............................................  $      (9,376)  $     (157)
                                                                   -------------  ------------
                                                                   -------------  ------------
Net loss.........................................................  $     (15,030)  $     (157)
                                                                   -------------  ------------
                                                                   -------------  ------------
Total number of shares used to compute basic earnings
  (loss) per share...............................................     28,145,000      105,000
                                                                   -------------  ------------
                                                                   -------------  ------------
Loss from operations:
  Basic loss per share...........................................  $       (0.33)  $    (1.50)
                                                                   -------------  ------------
                                                                   -------------  ------------
  Diluted loss per share.........................................  $       (0.33)  $    (1.50)
                                                                   -------------  ------------
                                                                   -------------  ------------
Net loss:
  Basic loss per share...........................................  $       (0.53)  $    (1.50)
                                                                   -------------  ------------
                                                                   -------------  ------------
  Diluted loss per share.........................................  $       (0.53)  $    (1.50)
                                                                   -------------  ------------
                                                                   -------------  ------------
</TABLE>

    Potential dilutive securities have been excluded from the computation for
the three months ended March 31, 1999 and for the period from February 20, 1998
(date of inception) to March 31, 1998 as their effect is antidilutive. Had the
Company been in a net income position for the three months ended March 31, 1999
and for the period from February 20, 1998 (date of inception) to March 31, 1998,
diluted

                                      F-24
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

        NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

      THREE MONTHS ENDED MARCH 31, 1999 AND PERIOD FROM FEBRUARY 20, 1998
                     (DATE OF INCEPTION) TO MARCH 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

3. EARNINGS PER SHARE (CONTINUED)
earnings per share would have included an additional 2,822,000 and 2,822,000
shares, respectively, related to outstanding stock options and stock
subscriptions (determined using the treasury stock method at the estimated
average market value).

4. PROPERTY AND EQUIPMENT

    Property and equipment at March 31, 1999, consist of the following:

<TABLE>
<S>                                                               <C>
Network equipment...............................................   $  27,145
Indefeasible right of use investments...........................      10,331
Leasehold improvements..........................................       3,647
Furniture, fixtures and office equipment........................       1,794
Construction in progress........................................       1,185
                                                                  -----------
                                                                      44,102
Less: accumulated depreciation and amortization.................      (2,556)
                                                                  -----------
  Property and equipment, net...................................   $  41,546
                                                                  -----------
                                                                  -----------
</TABLE>

5. INVESTMENT IN JOINT VENTURE

    On February 19, 1999, the parties to the joint venture executed a
development agreement. In accordance with the development agreement, the Company
provided a 109.5 million Deutsche Mark letter of credit (approximately $64.8
million) to the Developer to fund the Company's share of construction costs. To
secure the letter of credit, the Company placed securities with a value of $64.8
million in an escrow account at the bank.

6. LONG-TERM DEBT


    On February 19, 1999, the Company issued $160 million and 85 million Euro of
13 1/4% senior notes (the "Notes") with detachable warrants with a scheduled
maturity of February 15, 2009. Each Dollar warrant is initially exercisable to
purchase 6.71013 shares of common stock and each Euro warrant is initially
exercisable to purchase 7.53614 shares of common stock. Holders will be able to
exercise the warrants at a per share price equal to the greater of $2.00 per
share and the minimum par value required by Luxembourg law (currently 50
Luxembourg francs), subject to adjustment.


    The Company has the right to redeem any of the Notes beginning on February
15, 2004. The initial redemption price is 106.625% of their principal amount,
plus accrued interest. The redemption price will decline each year after 2004
and will be 100% of their principal amount, plus accrued interest, beginning on
February 15, 2007. In addition, before February 15, 2002, the Company may redeem
up to 35% of the aggregate amount of either series of Notes with the proceeds of
sales of its capital stock at 113.25% of their principal amount. The Company may
make such redemption only if after any such redemption, an amount equal to at
least 65% of the aggregate principal amount of such Notes originally issued
remains outstanding.

                                      F-25
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

        NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

      THREE MONTHS ENDED MARCH 31, 1999 AND PERIOD FROM FEBRUARY 20, 1998
                     (DATE OF INCEPTION) TO MARCH 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)

6. LONG-TERM DEBT (CONTINUED)
    The Notes contain covenants that restrict the Company's ability to enter
into certain transactions including, but not limited to, incurring additional
indebtedness, creating liens, paying dividends, redeeming capital stock, selling
assets, issuing or selling stock of restricted subsidiaries, or effecting a
consolidation or merger.

    The Company is obligated to use its best efforts to cause the Notes to
generally be freely transferable under the Securities Act of 1933 no later than
August 19, 1999. If this requirement is not met, then the interest on the Notes
will increase by 0.5% per annum until the Notes are generally freely
transferable.

    As required by the terms of the Notes, the Company used approximately $49.2
million of the net proceeds to purchase a portfolio of U.S. government
securities and approximately [Euro]26.9 million ($29.8 million) of the net
proceeds to purchase a portfolio of European government securities, and pledged
these portfolios for the benefit of the holders of the respective series of
Notes to secure and fund the first five interest payments.

7. COMMITMENTS AND CONTINGENCIES

    LEASES

    On February 2, 1999, the Company entered into a letter of intent for a lease
for network fiber, which requires monthly payments of $274, including operating
and maintenance costs, for 36 months, after which the Company will obtain a
15-year IRU for the leased fiber at no additional charge. The Company will be
required to pay an annual operating and maintenance fee of $250 for the term of
the IRU.

    PURCHASE COMMITMENTS

    On February 18, 1999, the Company entered into an agreement to purchase
fiber optic cable for the German Network during 1999 for $20,286, plus
value-added tax. The seller will either provide financing for the entire amount
of the purchase with the contract value to be repaid over three years in equal
annual installments beginning on December 31, 2001 together with interest, or
will allow the Company to make payment in full by December 31, 2000 without
interest. The loan, if provided, will bear interest at the U.S. dollar Libor
rate plus 4% per annum. If a loan is not provided, the seller is obligated to
provide certain additional equipment to the Company without charge.


8. SHAREHOLDERS' EQUITY



    On February 19, 1999, the Company issued $160 million and [Euro]85 million
of units each consisting of one 13 1/4% senior note and one detachable warrant.
Additional paid-in capital of $2.3 million represents the allocation of a
portion of the proceeds of such issuance to such warrants. The Company has
allocated approximately $9.0 of the $1000 issue price of each dollar unit to the
associated warrant and the remaining $991 to the dollar note. The Company has
allocated approximately [Euro]9.0 of the [Euro]1,000 issue price of each Euro
unit to the associated warrant and the remaining [Euro]991 to the Euro note. The
warrants were valued using the Black-Scholes option pricing model with the
following assumptions: dividend yield of 0%, risk-free interest rate of 5.1% and
expected option life of 10 years.


                                      F-26
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

        NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

      THREE MONTHS ENDED MARCH 31, 1999 AND PERIOD FROM FEBRUARY 20, 1998
                     (DATE OF INCEPTION) TO MARCH 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)


9. INCOME TAXES


    The Company has tax loss carryforwards of approximately $15,000 at March 31,
1999. The ability of the Company to fully realize deferred tax assets related to
these tax loss carryforwards in future years is contingent upon its success in
generating sufficient levels of taxable income before the statutory expiration
periods for utilizing such net operating losses lapses. Due to its limited
history, the Company was unable to conclude that realization of such deferred
tax assets in the near future was more likely than not. Accordingly, a valuation
allowance was recorded to offset the full amount of such assets.


10. SEGMENT INFORMATION


    Summarized financial information concerning the Company's reportable
segments for the three months ended March 31, 1999 is shown in the following
table. The "Other" column includes unallocated shared and corporate related
assets.


<TABLE>
<CAPTION>
                                                       VOICE
                                                     SERVICES     DATA SERVICES    OTHER    CONSOLIDATED
                                                   -------------  -------------  ---------  ------------
<S>                                                <C>            <C>            <C>        <C>
Revenues.........................................    $  11,911      $     382                $   12,293
Fixed cost contribution..........................        2,345            382                     2,727
Identifiable assets..............................       14,656          2,040      313,081      329,777
</TABLE>



11. SUBSEQUENT EVENTS


LONG-TERM DEBT

    The Company is in the process of negotiating a vendor financing agreement
with Nortel. The Nortel credit facility is to be for the financing of equipment
delivered by Nortel and for a limited amount of telecommunication equipment
supplied by other vendors.

SHAREHOLDERS' EQUITY

    Carrier1 has granted Options pursuant to the 1999 Share Option Plan to
acquire approximately 2,110,968 Shares at an exercise price of $2.00 per Share
plus applicable capital duty (currently 1% of the subscription price payable to
Carrier1 International by the subsidiary granting the applicable Option).
Carrier1 intends to grant additional Options in the future.


    As of May 1, the Company had substantially completed a restructuring of its
management equity arrangements. Pursuant to this restructuring, certain members
of management in effect have exchanged their equity interests and options that
they had held in Carrier One, LLC (the "LLC") (which holds a majority of the
equity of Carrier1 International) to acquire an equivalent dollar amount of
shares and options of Carrier1 International common stock.


PURCHASE COMMITMENTS

    On April 16, 1999, the Company signed an agreement to swap fiber wavelength
on the basis of a 15 year indefeasible right of use (IRU). Carrier1 is to
receive two unprotected wavelengths on diverse routes between Hamburg,
Copenhagen and Malmo and provides two unprotected wavelengths on the routes
between Hamburg and Frankfurt, Hamburg and Berlin, Berlin and Frankfurt in
exchange. The first wavelength to Scandinavia is scheduled for receipt by
Carrier1 in the first quarter of 1999, the second for early fourth quarter,
1999. Carrier1 will deliver the two wavelengths on the German ring during the
first quarter of 2000.

                                      F-27
<PAGE>
                  CARRIER1 INTERNATIONAL S.A. AND SUBSIDIARIES

        NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

      THREE MONTHS ENDED MARCH 31, 1999 AND PERIOD FROM FEBRUARY 20, 1998
                     (DATE OF INCEPTION) TO MARCH 31, 1998

            (IN THOUSANDS OF U.S. DOLLARS, EXCEPT SHARE INFORMATION)


11. SUBSEQUENT EVENTS (CONTINUED)

    On April 29, 1999, Carrier1 signed a letter of intent with Nortel for the
purchase of DWDM equipment to light up dark fiber in Germany and on the London
ring. The value of the purchases and the associated services to be performed
within 18 months amounts to $25 million.

    On May 7, 1999, Carrier1 signed a contract for the purchase of a 10-year
indefeasible right of use (IRU) for 2.5 Gbit/s of capacity from London to
Amsterdam, Frankfurt, Paris and Brussels in the amount of $15.0 million. The
capacity is scheduled to be delivered between June 1(st) and June 30(th) 1999.
Carrier1 sold in exchange to the same company a 10-year IRU for 2.5 Gbit/s of
capacity from London to Frankfurt, Amsterdam and Paris in the amount of $12.0
million. Carrier1 will pay $3.0 million on the date of acceptance, the remaining
$12.0 million will be offset by the delivery of Carrier1's wavelength.

PAYMENT TO NORTEL

    On April 16, 1999, Carrier1 paid Nortel for equipment delivered prior to
that date in the amount of $27.9 million.

                                      F-28
<PAGE>
- --------------------------------------------------------------------------------

                                   PROSPECTUS

- --------------------------------------------------------------------------------

                          Carrier1 International S.A.
                             Offer to exchange its
                    13 1/4% Senior Dollar Notes Due 2009 and
                       13 1/4% Senior Euro Notes Due 2009

                                          , 1999

- --------------------------------------------------------------------------------

                     Dealer Prospectus Delivery Obligation

Until            , 1999, all dealers that effect transactions in these
securities, whether or not participating in this offering, may be required to
deliver a prospectus. This is in addition to the dealers' obligation to deliver
a prospectus when acting as underwriters and with respect to their unsold
allotments or subscriptions.

- --------------------------------------------------------------------------------
<PAGE>
                                    PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 20. INDEMNIFICATION OF OFFICERS AND DIRECTORS

    Under Luxembourg law, civil liability of directors both to the company and
to third parties is generally considered to be a matter of public policy. It is
possible that Luxembourg courts would declare void an explicit or even implicit
contractual limitation on directors' liability to Carrier1 International S.A.
Carrier1 International S.A., however, can validly agree to indemnify the
directors against the consequences of liability actions brought by third parties
(including shareholders if such shareholders have personally suffered a damage
which is independent of and distinct from the damage caused to the company).

    Under Luxembourg law, an employee of Carrier1 International S.A. can only be
liable to Carrier1 International S.A. for damages brought about by his or her
willful acts or gross negligence. Any arrangement providing for the
indemnification of officers against claims of Carrier1 would be contrary to
public policy. Employees are liable to third parties under general tort law and
may enter into arrangements with Carrier1 International S.A. providing for
indemnification against third party claims.

    Under Luxembourg law, an indemnification agreement can never cover a willful
act or gross negligence.

    Carrier1 intends to implement an agreement providing for the indemnification
of officers and directors (the "Agreement"), having terms substantially similar
to the following:

        The corporation shall indemnify any director, any member of any
    committee designated by the board of directors and any fonde de pouvoir and
    his or her heirs, executors and administrators, against expenses (including
    attorneys' fees) judgments and fines in connection with any action, suit or
    proceeding or appeal therefrom, to which he or she may be made a party by
    reason of his or her being or having been a director or a member of any
    committee designated by the board of directors or a fonde de pouvoir of the
    corporation, or, at the request of the corporation, of any other corporation
    partnership, joint venture, trust or other enterprise in which the
    corporation holds a direct or indirect ownership interest or of which the
    corporation is a direct or indirect creditor and by which he or she is not
    entitled to be indemnified, provided that he or she acted in good faith and
    in a manner he or she reasonably believed to be in or not opposed to the
    best interests of the corporation, and, with respect to any criminal action
    or proceeding had no reasonable cause to believe his or her conduct was
    unlawful; and in the event of a settlement, such indemnification shall be
    provided for all expenses incurred and amounts paid in connection with such
    settlement unless the corporation is advised by its legal counsel that the
    person to be indemnified did not meet the above-indicated standard of
    conduct; except that in the case of an action or suit brought by the
    corporation against such a director, committee member or fonde de pouvoir to
    procure a judgment in favor of the corporation (1) such indemnification
    shall be limited to expenses (including attorneys' fees) actually and
    reasonably incurred by such person in the defense or settlement of such
    action or suit, and (2) notwithstanding, any other provisions hereof, no
    indemnification shall be made in respect of any claim, issue or matter as to
    which such person shall have been adjudged to be liable to the corporation
    unless and only to the extent that the Luxembourg Courts or the courts in
    which such action or suit was brought shall determine upon application that,
    despite the adjudication of liability but in view of all the circumstances
    of the case, such person is fairly and reasonably entitled to indemnity for
    such costs and expenses as the Luxembourg Court or such other court may deem
    legal and proper.

        The corporation may purchase and maintain insurance on behalf of any
    person who is or was or has agreed to become a director, committee member or
    fonde de pouvoir of the corporation, or is or was serving at the request of
    the corporation in any equivalent position in any such other corporation,
    partnership, joint venture, trust or other enterprise, against any liability
    asserted against him and incurred by him or on his behalf in any such
    capacity, or arising out of his status as such, whether or

                                      II-1
<PAGE>
    not the corporation would have the power to indemnify him against such
    liability under the provisions of the Agreement, provided that such
    insurance is available on acceptable terms, which determination shall be
    made by a vote of a majority of the entire board of directors. If the
    Agreement or any portion thereof shall be invalidated on any ground by any
    court of competent jurisdiction, then the corporation shall nevertheless
    indemnify each such director, committee member or fonde de pouvoir and may
    indemnify each employee or agent of the corporation as to costs, charges and
    expenses (including attorneys' fees), judgments, fines and amounts paid in
    settlement with respect to any action, suit or proceeding, whether civil,
    criminal, administrative or investigative, including an action by or in the
    right of the corporation, to the fullest extent permitted by any applicable
    portion of the Agreement that shall not have been invalidated and to the
    fullest extent permitted by applicable law.

        Subject to the applicable provisions of Luxembourg law and in particular
    Section 59 of the Luxembourg Law on Commercial Companies, no director,
    committee member or fonde de pouvoir of the corporation shall be liable to
    the corporation or its stockholders for his actions or omissions when
    performing his duties as a director, committee member or fonde de pouvoir,
    provided that nothing contained in the Agreement shall eliminate or limit
    the liability of a director, committee member or fonde de pouvoir (i) for
    any breach of his duty of loyalty to the corporation or its stockholder,
    (ii) for acts or omissions not in good faith or which involves intentional
    misconduct or a knowing violation of the law, or (iii) for any transaction
    from which the director derived an improper personal benefit.

ITEM 21. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

    (a) EXHIBITS


<TABLE>
<CAPTION>
  EXHIBIT
  NUMBER                                                   DESCRIPTION
- -----------  --------------------------------------------------------------------------------------------------------
<C>          <S>
       3.1   Articles of Incorporation of Carrier1 International S.A.*
       4.1   Indenture, dated as of February 19, 1999, between Carrier1 International S.A. and the Chase Manhattan
             Bank, as Trustee, relating to Carrier1 International S.A.'s 13 1/4 Senior Dollar Notes Due 2009*
       4.2   Form of 13 1/4 Senior Dollar Note (included in Exhibit 4.1)
       4.3   Indenture, dated as of February 19, 1999, between Carrier1 International S.A. and the Chase Manhattan
             Bank, as Trustee, relating to Carrier1 International S.A.'s 13 1/4 Senior Euro Notes Due 2009*
       4.4   Form of 13 1/4 Senior Euro Note (included in Exhibit 4.3)
       4.5   Notes Registration Rights Agreement, dated February 12, 1999, among Carrier1 International S.A., Morgan
             Stanley & Co. Incorporated, Salomon Smith Barney Inc., Warburg Dillon Read LLC and Bear, Stearns & Co.
             Inc.*
       4.6   U.S. Dollar Collateral Pledge and Security Agreement, dated as of February 19, 1999, among Carrier1
             International S.A., The Chase Manhattan Bank, as Trustee and The Chase Manhattan Bank, as securities
             intermediary*
       4.7   Euro Collateral Pledge and Security Agreement, dated as of February 19, 1999, among Carrier1
             International S.A., The Chase Manhattan Bank, as Trustee and The Chase Manhattan Bank AG, as securities
             intermediary*
       5.1   Opinion of Debevoise & Plimpton**
       5.2   Opinion of Bonn & Schmitt**
      10.1   Dollar Warrant Agreement, dated as of February 19, 1999, between Carrier1 International S.A. and The
             Chase Manhattan Bank, as Warrant Agent*
      10.2   Euro Warrant Agreement, dated as of February 19, 1999, between Carrier1 International S.A. and The Chase
             Manhattan Bank, as Warrant Agent*
</TABLE>


                                      II-2
<PAGE>

<TABLE>
<CAPTION>
  EXHIBIT
  NUMBER                                                   DESCRIPTION
- -----------  --------------------------------------------------------------------------------------------------------
<C>          <S>
      10.3   Warrants Registration Rights Agreement, dated as of February 12, 1999, between Carrier1 International
             S.A. and The Chase Manhattan Bank, as Warrant Agent*
      10.4   Carrier1 International S.A. 1999 Share Option Plan*
      10.5   Master Option Agreement, dated as of December 30, 1998, among Carrier1 International S.A., Carrier One
             LLC, Carrier1 International GmbH, Carrier1 B.V., Carrier1 France S.A.R.L., Carrier1 U.K. Limited and
             Carrier1 GmbH & Co. AG*
      10.6   Form of Option Agreement*
      10.7   Employment Agreement, dated as of March 4, 1998, between Carrier One AG and Stig Johansson*
      10.8   Employment Agreement, dated as of March 4, 1998, between Carrier One AG and Eugene A. Rizzo*
      10.9   Employment Agreement, dated as of March 26, 1998, between Carrier One AG and Terje Nordahl*
      10.10  Employment Agreement, dated as of March 4, 1998, between Carrier One AG and Joachim Bauer*
      10.11  Employment Agreement, dated as of March 4, 1998, between Carrier One AG and Kees van Ophem*
      10.12  Securities Purchase Agreement, dated as of March 1, 1999, among Carrier1, Carrier One LLC and the
             employee investors named therein
      10.13  Registration Rights Agreement, dated as of March 1, 1999, among Carrier1 International S.A., Carrier One
             LLC, Stig Johansson, Joachim Bauer, Gene Rizzo, Kees van Ophem, Terje Nordahl and the other parties
             named therein
      10.14  Securityholders' Agreement, dated as of March 1, 1999, among Carrier1 International S.A. and the
             employee investors named therein
      10.15  Development Agreement, dated as of February 19, 1999 by and among ViCaMe Infrastructure Development
             GmbH, Viatel German Asset GmbH, Carrier 1 Fiber Network GmbH & Co. oHG, Metromedia Fiber Network GmbH,
             Viatel, Inc. and Metromedia Fiber Network, Inc.***
      10.16  Amendment No. 1 to Securityholders' Agreement and Registration Rights Agreement, dated as of March 1,
             1999
      10.17  Amendment No. 2 to Securityholders' Agreement and Securities Purchase Agreement, dated as of March 1,
             1999
      10.18  Amendment No. 3 to Securityholders' Agreement and Securities Purchase Agreement, dated as of March 1,
             1999
      10.19  Amendment No. 4 to Securityholders' Agreement and Securities Purchase Agreement, dated as of March 1,
             1999
      12.1   Calculation of Ratio of Earnings to Fixed Charges*
      21.1   List of Subsidiaries of Carrier1 International S.A.*
      23.1   Consent of Deloitte & Touche Experta AG
      23.2   Consent of Debevoise & Plimpton (included in Exhibit 5.1 hereto)
      23.3   Consent of Bonn & Schmitt (included in Exhibit 5.2 hereto)
      24.1   Power of Attorney from Glenn M. Creamer*
      24.2   Power of Attorney from Jonathan E. Dick*
      24.3   Power of Attorney from Stig Johansson*
      24.4   Power of Attorney from Mark A. Pelson*
      24.5   Power of Attorney from Victor A. Pelson*
</TABLE>



                                      II-3

<PAGE>

<TABLE>
<CAPTION>
  EXHIBIT
  NUMBER                                                   DESCRIPTION
- -----------  --------------------------------------------------------------------------------------------------------
<C>          <S>
      24.6   Power of Attorney from Thomas J. Wynne*
      24.7   Power of Attorney from Joachim Bauer*
      25.1   Statement of Eligibility of The Chase Manhattan Bank on Form T-1*
      27.1   Financial Data Schedule
      99.1   Form of Letter of Transmittal (Dollar Notes and DTC Held Euro Notes)
      99.2   Form of Letter of Transmittal (Non-DTC Held Euro Notes)
      99.3   Form of Notice of Guaranteed Delivery (Dollar Notes and DTC Held Euro Notes)
      99.4   Form of Notice of Guaranteed Delivery (Non-DTC Held Euro Notes)
      99.5   Instructions to Registered Holders and/or Book Entry Transfer Participant from Beneficial Owner for
             Tender of 13 1/4% Senior Dollar Notes Due 2009 and 13 1/4% Senior Euro Notes Due 2009 (DTC Held) for
             registered 13 1/4% Senior Dollar Notes Due 2009 and 13 1/4% Senior Euro Notes Due 2009 (DTC Held)
      99.6   Instructions to Registered Holders and/or Book Entry Transfer Participant from Beneficial Owner for
             Tender of 13 1/4% Senior Euro Notes Due 2009 (Non-DTC Held) for registered 13 1/4% Senior Euro Notes Due
             2009 (Non-DTC Held)
</TABLE>


- ------------------------

*   Previously filed


**  To be filed by amendment



*** Confidential treatment requested as to certain portions; previously filed


(B) FINANCIAL STATEMENT SCHEDULES

    All schedules for which provision is made in the applicable accounting
regulations of the Securities and Exchange Commission are not required under the
related instructions, are inapplicable or not material, or the information
called for thereby is otherwise included in the financial statements or related
notes and therefore has been omitted.

ITEM 22. UNDERTAKINGS

    The undersigned registrant hereby undertakes:

    (1) To file, during any period in which offers or sales are being made, a
post-effective amendment to this registration statement:

        (i) To include any prospectus required by section 10(a)(3) of the
    Securities Act of 1933;

        (ii) To reflect in the prospectus any facts or events arising over the
    effective date of the registration statement (or the most recent
    post-effective amendment thereof) which, individually or in the aggregate,
    represent a fundamental change in the information set forth in the
    registration statement. Notwithstanding the foregoing, any increase or
    decrease in volume of securities offered (if the total dollar value of
    securities offered would not exceed that which was registered) and any
    deviation from the low or high end of the estimated maximum offering range
    may be reflected in the form of prospectus filed with the Commission
    pursuant to Rule 424(b) if, in the aggregate, the changes in volume and
    price represent no more than a 20% change in the maximum aggregate offering
    price set forth in the "Calculation of Registration Fee" table in the
    effective registration statement;

        (iii) To include any material information with respect to the plan of
    distribution not previously disclosed in the registration statement or any
    material change to such information in the registration statement.

                                      II-4
<PAGE>
    (2) That, for the purpose of determining any liability under the Securities
Act of 1933, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

    (3) To remove from registration by means of a post-effective amendment any
of the securities being registered which remain unsold at the termination of the
offering.

    Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
registrant pursuant to the foregoing provisions, or otherwise, the registrant
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Act and is,
therefore, unenforceable. In the event that a claim for indemnification against
such liabilities (other than payment by the registrant of expenses incurred or
paid by a director, officer or controlling person of the registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Act and will be governed by the final adjudication of
such issue.

                                      II-5
<PAGE>
                                   SIGNATURES


    PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED, THE
REGISTRANT HAS DULY CAUSED THIS AMENDMENT NO. 3 TO BE SIGNED ON ITS BEHALF BY
THE UNDERSIGNED, THEREUNTO DULY AUTHORIZED, IN THE CITY OF ZURICH ON JUNE 24,
1999.


<TABLE>
<S>                             <C>  <C>
                                By:                      *
                                     -----------------------------------------
                                     Name: Stig Johansson
                                     Title: Chief Executive Officer and
                                     President
</TABLE>

    PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, THIS AMENDMENT
NO. 3 HAS BEEN SIGNED BY THE FOLLOWING PERSONS IN THE CAPACITIES AND ON THE DATE
INDICATED.


          SIGNATURE              CAPACITY IN WHICH SIGNED           DATE
- ------------------------------  ---------------------------  -------------------
                                Director, Chief Executive
              *                   Officer and President
- ------------------------------    (Principal Executive          June 24, 1999
        Stig Johansson            Officer)

                                Chief Financial Officer
              *                   (Principal Financial
- ------------------------------    Officer and Principal         June 24, 1999
       Joachim W. Bauer           Accounting Officer)

              *                 Director
- ------------------------------                                  June 24, 1999
       Glenn M. Creamer

              *                 Director
- ------------------------------                                  June 24, 1999
       Jonathan E. Dick

              *                 Director
- ------------------------------                                  June 24, 1999
        Mark A. Pelson

              *                 Director
- ------------------------------                                  June 24, 1999
       Victor A. Pelson

              *                 Director
- ------------------------------                                  June 24, 1999
       Thomas J. Wynne

                                Authorized Representative
       CARRIER 1, INC.            in the U.S.                   June 24, 1999




<TABLE>
<S>   <C>                        <C>                         <C>
By:      /s/ KEES VAN OPHEM
      -------------------------
         Kees van Ophem, ITS                                    June 24, 1999
              SECRETARY

*By:     /s/ KEES VAN OPHEM
      -------------------------
           Kees van Ophem                                       June 24, 1999
        by Power of Attorney
</TABLE>


                                      II-6
<PAGE>
                                 EXHIBIT INDEX


<TABLE>
<CAPTION>
  EXHIBIT
  NUMBER                                                   DESCRIPTION
- -----------  --------------------------------------------------------------------------------------------------------
<C>          <S>
       3.1   Articles of Incorporation of Carrier1 International S.A.*
       4.1   Indenture, dated as of February 19, 1999, between Carrier1 International S.A. and the Chase Manhattan
             Bank, as Trustee, relating to Carrier1 International S.A.'s 13 Senior Dollar Notes Due 2009*
       4.2   Form of 13 Senior Dollar Note (included in Exhibit 4.1)
       4.3   Indenture, dated as of February 19, 1999, between Carrier1 International S.A. and the Chase Manhattan
             Bank, as Trustee, relating to Carrier1 International S.A.'s 13 Senior Euro Notes Due 2009*
       4.4   Form of 13 Senior Euro Note (included in Exhibit 4.3)
       4.5   Notes Registration Rights Agreement, dated February 12, 1999, among Carrier1 International S.A., Morgan
             Stanley & Co. Incorporated, Salomon Smith Barney Inc., Warburg Dillon Read LLC and Bear, Stearns & Co.
             Inc.*
       4.6   U.S. Dollar Collateral Pledge and Security Agreement, dated as of February 19, 1999, among Carrier1
             International S.A., The Chase Manhattan Bank, as Trustee and The Chase Manhattan Bank, as securities
             intermediary*
       4.7   Euro Collateral Pledge and Security Agreement, dated as of February 19, 1999, among Carrier1
             International S.A., The Chase Manhattan Bank, as Trustee and The Chase Manhattan Bank AG, as securities
             intermediary*
       5.1   Opinion of Debevoise & Plimpton**
       5.2   Opinion of Bonn & Schmitt**
      10.1   Dollar Warrant Agreement, dated as of February 19, 1999, between Carrier1 International S.A. and The
             Chase Manhattan Bank, as Warrant Agent*
      10.2   Euro Warrant Agreement, dated as of February 19, 1999, between Carrier1 International S.A. and The Chase
             Manhattan Bank, as Warrant Agent*
      10.3   Warrants Registration Rights Agreement, dated as of February 12, 1999, between Carrier1 International
             S.A. and The Chase Manhattan Bank, as Warrant Agent*
      10.4   Carrier1 International S.A. 1999 Share Option Plan*
      10.5   Master Option Agreement, dated as of December 30, 1998, among Carrier1 International S.A., Carrier One
             LLC, Carrier1 International GmbH, Carrier1 B.V., Carrier1 France S.A.R.L., Carrier1 U.K. Limited and
             Carrier1 GmbH & Co. AG*
      10.6   Form of Option Agreement*
      10.7   Employment Agreement, dated as of March 4, 1998, between Carrier One AG and Stig Johansson*
      10.8   Employment Agreement, dated as of March 4, 1998, between Carrier One AG and Eugene A. Rizzo*
      10.9   Employment Agreement, dated as of March 26, 1998, between Carrier One AG and Terje Nordahl*
      10.10  Employment Agreement, dated as of March 4, 1998, between Carrier One AG and Joachim Bauer*
      10.11  Employment Agreement, dated as of March 4, 1998, between Carrier One AG and Kees van Ophem*
      10.12  Securities Purchase Agreement, dated as of March 1, 1999, among Carrier1, Carrier One LLC and the
             employee investors named therein
      10.13  Registration Rights Agreement, dated as of March 1, 1999, among Carrier1 International S.A., Carrier One
             LLC, Stig Johansson, Joachim Bauer, Gene Rizzo, Kees van Ophem, Terje Nordahl and the other parties
             named therein
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
  EXHIBIT
  NUMBER                                                   DESCRIPTION
- -----------  --------------------------------------------------------------------------------------------------------
<C>          <S>
      10.14  Securityholders' Agreement, dated as of March 1, 1999, among Carrier1 International S.A. and the
             employee investors named therein
      10.15  Development Agreement, dated as of February 19, 1999 by and among ViCaMe Infrastructure Development
             GmbH, Viatel German Asset GmbH, Carrier 1 Fiber Network GmbH & Co. oHG, Metromedia Fiber Network GmbH,
             Viatel, Inc. and Metromedia Fiber Network, Inc.***
      10.16  Amendment No. 1 to Securityholders' Agreement and Registration Rights Agreement, dated as of March 1,
             1999
      10.17  Amendment No. 2 to Securityholders' Agreement and Securities Purchase Agreement, dated as of March 1,
             1999
      10.18  Amendment No. 3 to Securityholders' Agreement and Securities Purchase Agreement, dated as of March 1,
             1999
      10.19  Amendment No. 4 to Securityholders' Agreement and Securities Purchase Agreement, dated as of March 1,
             1999
      12.1   Calculation of Ratio of Earnings to Fixed Charges*
      21.1   List of Subsidiaries of Carrier1 International S.A.*
      23.1   Consent of Deloitte & Touche Experta AG
      23.2   Consent of Debevoise & Plimpton (included in Exhibit 5.1 hereto)
      23.3   Consent of Bonn & Schmitt (included in Exhibit 5.2 hereto)
      24.1   Power of Attorney from Glenn M. Creamer*
      24.2   Power of Attorney from Jonathan E. Dick*
      24.3   Power of Attorney from Stig Johansson*
      24.4   Power of Attorney from Mark A. Pelson*
      24.5   Power of Attorney from Victor A. Pelson*
      24.6   Power of Attorney from Thomas J. Wynne*
      24.7   Power of Attorney from Joachim Bauer*
      25.1   Statement of Eligibility of The Chase Manhattan Bank on Form T-1*
      27.1   Financial Data Schedule
      99.1   Form of Letter of Transmittal (Dollar Notes and DTC Held Euro Notes)
      99.2   Form of Letter of Transmittal (Non-DTC Held Euro Notes)
      99.3   Form of Notice of Guaranteed Delivery (Dollar Notes and DTC Held Euro Notes)
      99.4   Form of Notice of Guaranteed Delivery (Non-DTC Held Euro Notes)
      99.5   Instructions to Registered Holders and/or Book Entry Transfer Participant from Beneficial Owner for
             Tender of 13 1/4% Senior Dollar Notes Due 2009 and 13 1/4% Senior Euro Notes Due 2009 (DTC Held) for
             registered 13 1/4% Senior Dollar Notes Due 2009 and 13 1/4% Senior Euro Notes Due 2009 (DTC Held)
      99.6   Instructions to Registered Holders and/or Book Entry Transfer Participant from Beneficial Owner for
             Tender of 13 1/4% Senior Euro Notes Due 2009 (Non-DTC Held) for registered 13 1/4% Senior Euro Notes Due
             2009 (Non-DTC Held)
</TABLE>


- ------------------------

*   Previously filed


**  To be filed by amendment



*** Confidential treatment requested as to certain portions; previously filed


<PAGE>

                                                                   Exhibit 10.12


                          SECURITIES PURCHASE AGREEMENT


                                  by and among


                                CARRIER ONE, LLC,

                           CARRIER1 INTERNATIONAL S.A.

                                       AND

                               EACH OF PURCHASERS

                                AS DEFINED HEREIN



                            Dated as of March 1, 1999

<PAGE>

                                TABLE OF CONTENTS
                                -----------------

<TABLE>
<CAPTION>

                                                                                             Page
                                                                                             ----


                                    ARTICLE I

                                   DEFINITIONS

<S>                                                                                           <C>
Section 1.1  Definitions........................................................................1
Section 1.2. Hereof, Herein, etc................................................................5
Section 1.3. Computation of Time Periods........................................................5


                                ARTICLE II

                SALE AND PURCHASE OF PURCHASED SECURITIES

Section 2.1. Sale and Purchase of the Purchased Securities......................................5
Section 2.2. Closing............................................................................6
Section 2.3. Purchase of Additional Purchased Securities; Subsequent Closings...................6
Section 2.4. Use of Proceeds....................................................................8


                                ARTICLE III

              REPRESENTATIONS AND WARRANTIES OF THE COMPANY

Section 3.1  Organization and Existence.........................................................8
Section 3.2. Authorization; No Conflicts........................................................8
Section 3.3. Enforceability.....................................................................9
Section 3.4. Necessary Licenses.................................................................9
Section 3.5. Compliance with Law................................................................9
Section 3.6. Litigation........................................................................10


                                ARTICLE IV

                       PURCHASERS' REPRESENTATIONS

Section 4.1. Organization and Good Standing....................................................10
Section 4.2. Authorization.....................................................................10

</TABLE>


<PAGE>

<TABLE>
<CAPTION>

                                                                                             Page
                                                                                             ----
<S>                                                                                           <C>

Section 4.3. Enforceability....................................................................11


                                 ARTICLE V

             CONDITIONS TO PURCHASERS' OBLIGATION TO PURCHASE
                   AND THE COMPANY'S OBLIGATION TO SELL

Section 5.1. Purchasers' Closing Conditions....................................................11
Section 5.2. Company's Closing Conditions......................................................11


                                   ARTICLE VI

                              EXPENSES; INDEMNITY

Section 6.1. Expenses..........................................................................12
Section 6.2. Indemnification...................................................................13

</TABLE>

                                   ARTICLE VII

                                     NOTICES


                                  ARTICLE VIII

                       AMENDMENTS, WAIVERS AND ASSIGNMENT


                                   ARTICLE IX

                           GOVERNING LAW; JURISDICTION


                                       ii

<PAGE>

                                    ARTICLE X

                ENTIRE AGREEMENT; COUNTERPARTS; SECTION HEADINGS


                                   ARTICLE XI

                              WAIVER OF JURY TRIAL


                                   ARTICLE XII

                              ADDITIONAL PURCHASERS


                                       iii

<PAGE>

                         LIST OF EXHIBITS AND SCHEDULES


Exhibit A       Articles of Association
Exhibit B       Form of Registration Rights Agreement
Exhibit C       Form of Securityholder's Agreement
Exhibit D       Form of Luxembourg law opinion

Schedule 2.1.      List of Purchasers


                                       iv

<PAGE>

                          SECURITIES PURCHASE AGREEMENT


                          CARRIER1 INTERNATIONAL S.A.
                          c/o Carrier1 International GmbH
                          Militarstrasse 36
                          8004 Zurich, Switzerland

                                                             As of March 1, 1999



To the Persons Listed in
Schedule 2.1 of this Agreement
c/o Carrier1 International GmbH
Militarstrasse 36
8004 Zurich, Switzerland

Ladies and Gentlemen:

                The undersigned, Carrier1 International S.A., a Luxembourg
societe anonyme (the "Company"), hereby agrees with you as follows:

                                    ARTICLE I

                                   DEFINITIONS

                SECTION 1.1  DEFINITIONS. Capitalized terms used herein and not
otherwise defined herein shall have the meanings set forth in this Article I:

                ADDITIONAL PURCHASER. The term "Additional Purchaser" shall have
the meaning provided in Article XII.

                AFFILIATE. The term "Affiliate" shall mean any Person directly
or indirectly controlling, controlled by or under direct or indirect common
control with the Company (or other specified Person) and shall include (a) any
Person who is a manager, officer, director or beneficial owner of at least 8% of
the then Equity Securities (on a fully diluted basis) of the Company (or other
specified Person) and Family Members of any such Person, (b) any Person of which
the Company (or other specified Person) or an Affiliate (as defined in clause
(a) above) of the Company (or other specified Person) shall, directly


<PAGE>

or indirectly, either beneficially own at least 10% of the then outstanding
Equity Securities or constitute at least a l0% equity participant, and (c) in
the case of a specified Person who is an individual, Family Members of such
Person.

                ARTICLES. The term "Articles" shall mean that certain Articles
of Association of the Company in the form of Exhibit A attached hereto, as
amended, modified, supplemented or restated from time to time.

                BUSINESS DAY. The term "Business Day" shall mean any day other
than Saturday, Sunday or other day on which commercial banks in the state of
Rhode Island are required or permitted to close by law.

                CARRIER ONE. The term "Carrier One" means Carrier One LLC, a
Delaware limited liability company.

                CHARTER. The term "Charter" means the certificate or articles of
incorporation, by-laws, statute, constitution, joint venture, certificate of
limited partnership, partnership agreement, articles of organization, limited
liability company operating agreement or other organizational document of any
Person other than an individual, including the Articles, each as from time to
time amended or modified.

                COMPANY. The term "Company" shall mean Carrier1 International
S.A., a Luxembourg societe anonyme, or any corporation into which Carrier1
International S.A. is converted or merged.

                CONTRACT. The term "Contract" shall mean all material contracts,
leases, plans and commitments and other agreements entered into by the Company
or any Subsidiary which are in writing or have been orally agreed to by the
Company or any of its Subsidiaries.

                DOLLARS. The term "Dollars" and "$" shall mean United States
dollars.

                EMPLOYMENT AGREEMENTS. The term "Employment Agreements" shall
mean those certain Employment Agreements, between Carrier1 International GmbH,
and each of the Management, as the same may be amended, modified or supplemented
from time to time.

                ENVIRONMENT. The term "Environment" shall mean soil, surface
waters, groundwater, land, stream sediments, surface or subsurface strata,
ambient air and any environmental medium, whether indoors or outdoors.

                ENVIRONMENTAL LAWS. The term "Environmental Laws" shall mean
all federal, foreign, state, local or municipal environmental, health or
safety-related laws, regulations, by-laws, rules, ordinances, judicial or
administrative decrees or decisions, orders or requirements applicable to the
Company or any of its Subsidiaries relating to the physical or environmental
condition or use of their respective properties, their respective businesses
or pollution or protection of human health or the Environment, including,
without limitation, the Comprehensive Environmental Response Compensation and
Liability Act, 42 U.S.C., Section 9601, et seq., as amended ("CERCLA"), the
Resource Conservation and Recovery Act, 42 U.S.C. Section 6901, et. seq., as
amended, the Clear Air Act, 42 U.S.C. Section 7401 et seq., as amended, the
Clean Water Act, 33 U.S.C. Section 1251, et seq., the Toxic Substance Control
Act, 15 U.S.C. Section 2601 et seq., the

                                        2

<PAGE>

Occupational Safety and Health Act, laws relating to Release or threatened
Releases manufacture, generation, processing, distribution, use, treatment,
storage, abatement, existence, holding, Release, transport or handling of
Hazardous Substances, and all laws and regulations with regard to record
keeping, notification, disclosure and reporting requirements respecting
Hazardous Substances.

           EQUITY SECURITIES. The term "Equity Securities" means all authorized
Shares or capital stock of the Company, including (i) all classes of Shares or
capital stock, voting and non-voting (including, without limitation, the
Purchased Securities), (ii) any warrants, options or other rights to subscribe
for or to acquire, directly or indirectly, whether pursuant to any division or
split of any class of Share or capital stock of the Company or in connection
with a combination, exchange, reorganization, recapitalization,
reclassification, merger, consolidation or similar business combination
transaction involving the Company or otherwise, (iii) any other equity interests
in the Company or any bonds, notes, debentures, or other securities convertible
into or exchangeable for, directly or indirectly, any Shares, capital stock or
equity interests of the Company and (iv) any interests in any of the foregoing
in each case outstanding at any time.

           GOVERNMENTAL ENTITIES. The term "Governmental Entities" shall have
the meaning given such term in the Securityholders' Agreement.

           HAZARDOUS SUBSTANCES. The term "Hazardous Substances" means any
pollutant, contaminant, toxic substance, hazardous waste, hazardous material,
or hazardous substance, or any oil, petroleum or petroleum product, each as
defined or listed in, or classified pursuant to, any Environmental Laws.

           INITIAL CLOSING DATE. The term "Initial Closing Date" shall mean
January 15, 1999 or such other date as the Company and the Purchasers may agree
upon.

           LICENSES. The term "Licenses" shall mean all licenses, permits,
consents, approvals, concessions and authorizations of all Governmental
Entities, whether foreign, federal, state or local, including, without
limitation, any state public utilities commission and their equivalents in
foreign countries.

           LIEN. The term "Lien" shall mean (a) any encumbrance, mortgage,
pledge, lien, charge or other security interest of any kind upon any property or
assets of any character, or upon the income or profits therefrom; (b) any
acquisition of or agreement to have an option to acquire any property or assets
upon conditional sale or other title retention agreement, device or arrangement
(including a capitalized lease); or (c) any sale, assignment, pledge or other
transfer for security of any accounts, general intangibles or chattel paper,
with or without recourse.

           MAJORITY PURCHASERS. The term "Majority Purchasers" shall mean, at
any time, the holders of at least a majority of the outstanding Purchased
Securities.

           MANAGEMENT. The term "Management" shall mean Stig Johansson, Joachim
Bauer, Eugene A. Rizzo, Kees van Ophem, Neil Craven, Philip Poulter, Terje
Nordahl and Edward Gross.


                                        3

<PAGE>

           MATERIAL ADVERSE EFFECT. The term "Material Adverse Effect" shall
mean, with respect to any Person, any effect that is, or series of related
effects that are, in the aggregate, materially adverse to the business, assets,
properties, condition (financial or otherwise) or prospects of such Person.

           OPTION AGREEMENTS. The term "Option Agreements" shall mean the Option
Agreements of even date herewith between Carrier One, the Company or its
Subsidiaries and certain of their respective employees.

           PERSON. The term "Person" shall mean an individual, partnership,
limited liability company, corporation, association, trust, joint venture,
unincorporated organization and any Governmental Entity.

           PURCHASED SECURITIES. The term "Purchased Securities" shall mean the
Shares held by Purchasers on the date hereof (whether or not acquired pursuant
to this Agreement) and Shares being purchased by the Purchasers pursuant to
Article II of this Agreement and any Shares, capital stock or other securities
of the Company issued or issuable upon an exchange, conversion, reorganization,
reclassification, recapitalization, merger, consolidation or other similar
business transaction involving the Company, its Subsidiaries or otherwise.

           PURCHASER. The term "Purchaser" shall mean the several purchasers
named in Schedule 2.1 (individually, a "Purchaser" and collectively, the
"Purchasers") and their respective successors and assigns and shall include
Additional Purchasers pursuant to Article XII and shall include Carrier One.

           RELATED AGREEMENTS. The term "Related Agreements" shall mean the
Articles, the Securityholders' Agreement, the Registration Rights Agreement and
the Option Agreements.

           RELEASE. The term "Release" shall mean a "Release" as defined in any
Environmental Laws, including, but not limited to, any releasing, spilling,
leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping,
leaching, dispersing or dumping into the Environment in violation of any
Environmental Laws.

           REGISTRATION RIGHTS AGREEMENT. The term "Registration Rights
Agreement" shall mean that certain Registration Rights Agreement, dated the date
hereof, by and among the Company and certain of its shareholders in the form of
Exhibit B attached hereto, as the same may be amended, modified or supplemented
from time to time.

           SECURITIES ACT. The term "Securities Act" shall mean all applicable
securities laws, rules, regulations, notices and policies in force in the United
States, as amended, modified or supplemented from time to time.

           SECURITYHOLDERS' AGREEMENT. The term "Securityholders' Agreement"
shall mean the Securityholders' Agreement, dated the date hereof, among the
Company and certain of its shareholders, in the form of Exhibit C attached
hereto, as the same may be amended, modified or supplemented from time to time.


                                        4

<PAGE>

           SHARES.  The term "Shares" shall mean the shares of the Company.

           SUBSIDIARY. The term "Subsidiary" shall mean any Person of which
the Company or other specified Person now or hereafter shall at the time own,
directly or indirectly through a Subsidiary, at least a majority of the
outstanding Equity Securities (or other shares of beneficial interest)
entitled to vote generally.

           "TAX" OR "TAXES". The term "Tax" or "Taxes" shall mean all taxes,
charges, fees, levies, imposts and other assessments, including all income,
sales, use, goods and services, value added, capital, capital gains, alternative
net worth, transfer, profits, withholding, payroll, employer health, excise,
real property and personal property taxes, and any other taxes, customs duties,
fees, assessments or similar charges in the nature of a tax, including, without
limitation, pension plan contributions and workers compensation premiums,
together with any interest, fines and penalties imposed by any Governmental
Entity, and whether disputed or not.

           SECTION 1.2. HEREOF, HEREIN, ETC. The words "hereof", "herein" and
"hereunder" and words of similar import when used in this Agreement shall refer
to this Agreement as a whole and not to any particular provision of this
Agreement. Unless otherwise specified herein, the term "or" has the inclusive
meaning represented by the term "and/or" and the term "including" is not
limiting. All references as to "Sections", "Subsections", "Articles",
"Schedules" and "Exhibits" shall be to Section, Subsections, Articles, Schedules
and Exhibits, respectively, of this Agreement unless otherwise specifically
provided.

           SECTION 1.3. COMPUTATION OF TIME PERIODS. In the computation of
periods of time from a specified date to a later specified date, unless
otherwise specified herein the words "commencing on" mean "commencing on and
including", the word "from" means "from and including" and the words "to" and
"until" each means "to and including".


                                   ARTICLE II

                    SALE AND PURCHASE OF PURCHASED SECURITIES

           SECTION 2.1. SALE AND PURCHASE OF THE PURCHASED SECURITIES.
Subject to all of the terms and conditions hereof and in reliance on the
representations and warranties set forth or referred to herein, the Company
agrees to issue and sell to each Purchaser and each Purchaser agrees to
purchase, on the Initial Closing Date, the number of Purchased Securities set
forth on Schedule 2.1, in the case of Carrier One, or the number of Purchased
Securities set forth in the separate notice of allocation and acceptance
signed by the Company and such Purchaser on or prior to the date hereof, at a
purchase price per Share of US$ 2.00 (the "Per Share Price") (the "Initial
Closing"). The sale of the Purchased Securities to each Purchaser at the
Initial Closing shall constitute a separate sale hereunder.

                                        5

<PAGE>

           SECTION 2.2. CLOSING. The Initial Closing of the purchase and sale
of the Purchased Securities contemplated by Section 2.1 will take place at the
offices of Etude Notariale Gerard Lecuit, 300 Route de Thionville - B.P. 68 -
Hesperange, 5801 Luxembourg at 10:00 a.m. on January 15, 1999, or at such other
time, date and place as the parties hereto may agree upon. Subject to the
satisfaction of the conditions to closing set forth in Article V, (i) as payment
in full for the Purchased Securities being purchased by the Purchasers under
this Agreement on the Initial Closing Date, on the Initial Closing Date each
Purchaser shall deliver or cause to be delivered to the Company, in immediately
available funds, an amount equal to (a) the aggregate number of Purchased
Securities set forth on SCHEDULE 2.1 in the case of Carrier One, or the number
of Purchased Securities set forth in the separate notice of allocation and
acceptance signed by the Company and such Purchaser on or prior to the date
hereof, multiplied by (b) US$ 2.00 (the "Per Share Price"), and (ii) upon
confirmation of receipt of such funds in the capital and/or surplus accounts of
the Company, Carrier One shall cause the capital of the Company to be increased
accordingly and the Company shall issue the Purchased Securities to such
Purchaser. As soon as practicable following the Closing, the Company shall
register the Purchaser as the owner of the Purchased Securities in the share
register of the Company and shall cause certificates representing the Purchased
Securities to be delivered to such Purchaser or its designated custodian.

           SECTION 2.3. PURCHASE OF ADDITIONAL PURCHASED SECURITIES; SUBSEQUENT
CLOSINGS. (a) At the Subsequent Closings (as defined below), subject to the
terms and conditions set forth herein, the Company shall sell to Carrier One,
and Carrier One agrees to purchase from the Company, an aggregate number of
Shares at the Per Share Price which, when aggregated with all other Shares
previously acquired by Carrier One (whether or not still held by Carrier One),
does not exceed 30.4 million Shares at the Per Share Purchase Price. As of the
date hereof, Carrier One has already subscribed for 18,865,206 Shares, of which
18,845,206 have been paid in full, and 19,999 have been one-quarter paid up.

           (b) Carrier One may, upon at least thirty (30) days prior written
notice to the Company (the "Call Notice"), designate a date (which shall be a
Business Day) for the closing (a "Subsequent Closing") of the purchase by
Carrier One of Additional Purchased Securities (each a "Subsequent Closing
Date"), which Call Notice shall specify the aggregate number of Purchased
Securities to be purchased by Carrier One on such Subsequent Closing Date.
The determination of whether to make a Call Notice shall be in the sole and
absolute discretion of Carrier One. No Call Notices shall be given after
March 31, 2002 without the written approval of the Majority Purchasers.
Notwithstanding the foregoing, Carrier One shall be obligated to cause one or
more Call Notices to be made to assure that the Company and its Subsidiaries
have sufficient funds to pay the amounts owed to Management under the
Employment Agreements from the date hereto to March 1, 1999 (the "Management
Compensation Calls"). Each Subsequent Closing will take place at the offices
of Etude Notariale Gerard Lecuit, 300 Route de Thionville - B.P.68 -
Hesperange, 5801, Luxembourg at 10:00 a.m. on the date specified in the Call
Notice or at such other time, date and place as the Company and Carrier One
may agree upon. Subject to the satisfaction of the conditions to closing set
forth in this Section 2.3, at each Subsequent Closing (i) Carrier One shall
deliver or cause to be delivered to the Company, in immediately


                                        6

<PAGE>

available funds, an amount equal to (a) the aggregate number of Purchased
Securities set forth in the Call Notice, multiplied by (b) the Per Share
Price, and (ii) upon confirmation of receipt of such funds in the capital
and/or surplus accounts of the Company, the capital of the Company shall be
increased accordingly and the Company shall issue the Purchased Securities to
Carrier One. As soon as practicable following each Subsequent Closing, the
Company shall register Carrier One as the owner of the Purchased Securities
in the share register of the Company and shall cause certificates
representing the Purchased Securities to be delivered to Carrier One or its
designated custodian.

           (c) The obligation of Carrier One to purchase and pay for the
Additional Purchased Securities at each Subsequent Closing is subject to (i)
each of the Company's representations and warranties set forth in Article III
being true and correct in all material aspects as of such Subsequent Closing
Date, (ii) there shall have occurred no material adverse change in the assets,
business, condition (financial or otherwise) or prospects of the Company or its
Subsidiaries taken as a whole as determined by Carrier One in its sole and
absolute discretion, (iii) there shall have been no material breach or violation
by any party (other than Carrier One) under any Related Agreement, provided the
satisfaction of the conditions set forth in clauses (i) - (iii) shall not be
applicable to Management Compensation Calls. Any one or more of such conditions
may be waived with the prior written consent of Carrier One, in its sole and
absolute discretion, provided that a waiver of any of the foregoing conditions
with respect to a Subsequent Closing shall not operate as a waiver of such
condition with respect to any other Subsequent Closing.

           (d) The obligations of the Company to sell and issue the
Additional Purchased Securities at each Subsequent Closing is subject to each
of Carrier One's representations and warranties set forth in Article IV being
true and correct in all material respect to as of such Subsequent Closing
Date. Such condition may be waived with the prior written consent of the
Company, in its sole and absolute discretion, provided that a waiver of the
foregoing condition with respect to a Subsequent Closing shall not operate as
a waiver of such condition with respect to any other Subsequent Closing.

           (e) Each Purchaser hereby consents to the purchase of Purchased
Securities by Carrier One pursuant to this Section 2.3, and waives any right of
preemption or similar rights that it may have otherwise had in respect of such
Purchased Securities. Each Purchaser acknowledges and agrees that sales and
purchases of Shares pursuant to Section 2.3 shall be made at the Per Share Price
regardless of the financial condition or valuation of the Company at the time
such purchase or sale is consummated and hereby agrees to waive any right to
object to such sale or purchase or to require any appraisal or valuation in
connection therewith.

           (f) Notwithstanding anything else contained in this Section 2.3,
so long as that certain Unlimited Guaranty (as amended, modified,
supplemented, extended, renewed, replaced or restated from time to time, the
"Guaranty") issued by Providence Equity Partners L.P. ("PEP") in favor of
Fleet National Bank is in effect and has not been terminated or PEP is
otherwise obligated thereunder, the maximum number of Purchased Securities to
be purchased by Carrier One at Subsequent Closings after the


                                        7

<PAGE>

date hereof shall be reduced at the request of Carrier One by an amount equal
to that number of Additional Purchased Securities as equals the quotient of
(i) the maximum amount of PEP's obligations and liabilities under the
Guaranty at any time divided by (ii) the Per Share Purchase Price. In
addition, to the extent that PEP has paid any amount under the Guaranty, and
for so long as PEP shall not have been reimbursed for such payment in full,
Carrier One shall have the right, in its sole discretion, to require the
Company to issue to PEP, Carrier One or its designee, in exchange for the
release or contribution of the Company's or its affiliates' reimbursement
obligations with respect to such payment, that number of Additional Purchased
Securities as equals the quotient of (x) any amounts paid by PEP in respect
of the Guaranty and not theretofore reimbursed divided by (y) the Per Share
Purchase Price.

           SECTION 2.4. USE OF PROCEEDS. Proceeds from the sale of the
Purchased Securities hereunder shall be used for working capital and general
corporate purposes as determined from time to time by the Company's Board of
Directors.


                                   ARTICLE III

                  REPRESENTATIONS AND WARRANTIES OF THE COMPANY

           In order to induce the Purchasers to enter into this Agreement and to
purchase the Purchased Securities, the Company hereby represents and warrants as
follows:

           SECTION 3.1   ORGANIZATION AND EXISTENCE.

           (a) The Company is duly organized, validly existing and in good
standing in its jurisdiction of organization and is duly qualified as a societe
anonyme and authorized to do business in all other jurisdictions in which the
nature of its business or property makes such qualification necessary except
where the failure to so qualify would not have a Material Adverse Effect. The
Company has the power to own its properties and to carry on its business as now
conducted and as proposed to be conducted.

           (b) Each of the Company's Subsidiaries is duly organized, validly
existing and in good standing in its jurisdiction of incorporation and is duly
qualified as a foreign entity and authorized to do business in all other
jurisdictions in which the nature of its business or property makes such
qualification necessary and where the failure to so qualify would not have a
Material Adverse Effect. Each of the Subsidiaries has the power to own its
properties and to carry on its business as now conducted and as proposed to be
conducted.

           SECTION 3.2. AUTHORIZATION; NO CONFLICTS. The execution, delivery
and performance by the Company of this Agreement and of each Related Agreement,
and the issuance and sale by the Company of the Purchased Securities hereunder,
(a) are within its power and authority, and (b) have been duly authorized by all
necessary action of the Company and by all other requisite proceedings. Neither
the execution and delivery by the Company of this Agreement or any Related
Agreement nor the consummation by the Company of the transactions contemplated
thereby (including,


                                        8

<PAGE>

without limitation, the purchase and sale of the Purchased Securities
hereunder) (a) will violate any provision of the Charter of the Company or
any of its Subsidiaries, (b) will violate or conflict with any applicable
statute, law, ordinance, rule, regulation, order, judgment, writ, injunction,
license, permit or decree applicable to the Company or any of its
Subsidiaries, (c) will conflict with or constitute a violation of or a
default (or an event which with notice or lapse of time or both, would
constitute a default) under, or will result in the termination of, or
accelerate performance required by, any contract to which the Company or any
of its Subsidiaries is a party or to which any of the assets or properties of
the Company or any of its Subsidiaries are subject, (d) will result in the
creation of any Lien upon any of the Equity Securities of the Company or any
of its Subsidiaries or upon any of the property or assets of the Company or
any of its Subsidiaries, or (e) will require the consent, authorization or
approval of, or notice to or filing or registration with, any Person.

           SECTION 3.3. ENFORCEABILITY. The execution and delivery by the
Company of this Agreement and of each of the Related Agreements, and the
issuance and sale by the Company of the Purchased Securities hereunder, will
result in legally binding obligations of the Company enforceable against the
Company in accordance with the respective terms and provisions hereof and
thereof.

           SECTION 3.4. NECESSARY LICENSES. (a) The Company and its
Subsidiaries hold all necessary Licenses which are required in connection
with the ownership and operation of their businesses as currently conducted.
All Licenses are in full force and effect. The Company and its Subsidiaries
have complied with the terms of the Licenses which they hold and there are no
pending modifications, amendments or revocations of the Licenses which would
adversely affect the ownership or the operation of its business. All fees due
and payable from the Company or any of its Subsidiaries to Governmental
Entities pursuant to the Licenses have been paid. All reports required of the
Company or any of its Subsidiaries to be filed in connection with the
Licenses have been timely filed and are accurate and complete.

                (b) No registrations, filings, applications, notices, transfers,
consents, approvals, audits, qualifications, waivers or other action of any kind
is required by virtue of the execution and delivery of this Agreement or any
Related Agreement, or of the consummation of the transactions contemplated
hereby or thereby (a) to avoid the loss of any License or any asset, property or
right pursuant to the terms thereof or the violation or breach of any law
applicable thereto, or (b) to enable the Company and its Subsidiaries to hold
and enjoy the same after the Initial Closing Date (or the Subsequent Closing
Date, as the case may be) in the conduct of its business as conducted
immediately prior to the Initial Closing Date (or the Subsequent Closing Date,
as the case may be). In particular, execution and delivery of this Agreement and
the Related Agreements, and consummation of the transactions contemplated
therein, will not constitute a change of control in the Company or its
Subsidiaries, or otherwise require authorization, approval, consent, or filing
of registration with any Governmental Entity, and will not violate or conflict
with any applicable provision of the laws, rules and regulations administered by
any Governmental Entity.

           SECTION 3.5. COMPLIANCE WITH LAW. Neither the Company nor any
Subsidiary is in default under, or in violation of, any laws, rules or
regulations


                                        9

<PAGE>

(including, without limitation, foreign, federal, state or local laws, rules
or regulations relating to the issuance or sale of securities,
telecommunications, anti-trust, occupational safety, the protection of the
environment, transportation, storage or disposal of hazardous waste,
anti-pollution and air and water quality laws), or any Licenses, granted by,
or any judgment, decree, writ, injunction or order of, any Governmental
Entity, applicable to its business or any of its properties or assets, which
defaults and violations would in the aggregate expose the Company and its
Subsidiaries to liabilities in excess of an aggregate of US$ 50,000 or
otherwise materially adversely affect the assets or properties or business or
operations of the Company and its Subsidiaries or requiring or prohibiting
future activities.

           Neither the Company nor any Subsidiary has received any notification
alleging any violations of any of the foregoing with respect to which adequate
corrective action has not been taken.

           SECTION 3.6. LITIGATION. (a) There is no suit, claim, action,
proceeding or investigation pending or, to the best knowledge of the Company
after inquiring of its officers and employees, threatened against or adversely
affecting the Company or any of its Subsidiaries, any of their assets or
properties, any officer or director of the Company or any of its Subsidiaries or
the consummation of the transactions contemplated by this Agreement or any
Related Agreement, at law or in equity or before any Governmental Entity or
before any arbitrator of any kind and there is no reasonable basis for any such
suit, claim, action, proceeding or investigation. Neither the Company nor any
Subsidiary nor any officer or director thereof is a party to or subject to (x)
any judgment, order, writ, injunction or decree affecting it or any of its
assets or properties or requiring or prohibiting future activities or (y) any
settlement agreement.

           (b) Neither the Company nor any Subsidiary nor any officer or
director thereto has been party to administrative or regulatory proceedings or
other governmental investigations or inquiries, pending or threatened, affecting
business operations of the Company or any Subsidiary.


                                   ARTICLE IV

                           PURCHASERS' REPRESENTATIONS

           SECTION 4.1. ORGANIZATION AND GOOD STANDING. Each Purchaser that is
not an individual represents that it is validly existing and in good standing
under the laws of its state of formation.

           SECTION 4.2. AUTHORIZATION. Each Purchaser represents that this
Agreement and the Related Agreements to which it is a party have been executed
by him, or in the case of a Purchaser which is not an individual by a duly
authorized Person on its behalf and the execution, delivery and performance
hereof and thereof (a) have been duly authorized by all appropriate action, and
(b) will not violate the provision of any material law or regulation of any
Governmental Entity applicable to


                                        10

<PAGE>

it or constitute a violation of any material agreement or instrument by which
it is bound.

           SECTION 4.3. ENFORCEABILITY. Each Purchaser represents that the
execution and delivery of this Agreement and the Related Agreements and the
transactions contemplated thereunder will result in legally binding obligations
of such Purchaser enforceable against such Purchaser in accordance with the
respective terms and provisions hereof and thereof, subject, however, to
limitations with respect to enforcement imposed by law in connection with
bankruptcy or similar proceedings to the extent that equitable remedies such as
specific performance and injunction are in the discretion of the court from
which they are sought.

                                    ARTICLE V

                CONDITIONS TO PURCHASERS' OBLIGATION TO PURCHASE
                      AND THE COMPANY'S OBLIGATION TO SELL

           SECTION 5.1. PURCHASERS' CLOSING CONDITIONS. Each Purchaser's
obligation to purchase the Purchased Securities pursuant to Section 2.1 is
subject to compliance by the Company with its agreements herein contained, and
to the satisfaction, on or prior to the Initial Closing Date of the following
conditions:

           (a) RELATED AGREEMENTS. Each of the Related Agreements shall have
been executed and delivered in a form satisfactory to the Purchasers. All
covenants, agreements and conditions contained in the Related Agreements which
are to be performed or complied with on or prior to the Initial Closing Date
shall have been performed or complied with in all material respects.

           (b) LEGAL OPINION. The Purchaser shall have received from Schmitt &
Bonn, Luxembourg counsel to the Company, an opinion substantially in the form of
Exhibit D attached hereto.

           (c) LEGALITY; GOVERNMENTAL AND OTHER AUTHORIZATIONS. The purchase of
the Purchased Securities shall not be prohibited by any law or governmental
order or regulation, and shall not subject any Purchaser to any penalty, special
Tax, or other onerous condition. All necessary consents, approvals, Licenses,
orders and authorizations of, and registrations, declarations and filings with,
any Governmental Entity or any other Person, with respect to any of the
transactions contemplated by this Agreement or any of the Related Agreements,
shall have been duly obtained or made and shall be in full force and effect.

           (d) NO DEFAULT. The Company shall not be in material default under
any of its Contracts.

           (e) GENERAL. All instruments and corporate proceedings in connection
with the transactions contemplated by this Agreement and the Related Agreements
shall be satisfactory in form and substance to the Purchasers, and the
Purchasers shall have received copies of all documents, including, without
limitation, records of corporate


                                       11

<PAGE>

or other proceedings and consents which the Purchaser may have reasonably
requested in connection therewith.

           SECTION 5.2. COMPANY'S CLOSING CONDITIONS. The Company's obligation
to sell the Purchased Securities pursuant to SECTION 2.1 is subject to the
representations and warranties of the Purchasers contained herein being true and
correct in all material respects on and as of the Initial Closing Date, and to
the satisfaction, on or prior to the Initial Closing Date of the following
conditions:

           (a) RELATED AGREEMENTS. Each of the Related Agreements shall have
been executed and delivered in a form satisfactory to the Company. All
covenants, agreements and conditions contained in the Related Agreements which
are to be performed or complied with on or prior to the Initial Closing Date
shall have been performed or complied with in all material respects.

           (b) LEGALITY; GOVERNMENTAL AND OTHER AUTHORIZATIONS. The purchase of
the Purchased Securities shall not be prohibited by any law or governmental
order or regulation, and shall not subject the Company to any penalty, special
Tax, or other onerous condition. All necessary consents, approvals, Licenses,
orders and authorizations of, and registrations, declarations and filings with,
any Governmental Entity or any other Person, with respect to any of the
transactions contemplated by this Agreement or any of the Related Agreements,
shall have been duly obtained or made and shall be in full force and effect.

           (c) GENERAL. The Company shall have received copies of all documents,
including, without limitation, documents evidencing the compliance of
sub-paragraph (b) above, which the Company may have reasonably requested in
connection therewith.


                                   ARTICLE VI

                               EXPENSES; INDEMNITY

           SECTION 6.1. EXPENSES. The Company hereby agrees to pay at the
Initial Closing and each Subsequent Closing all reasonable fees, costs and
expenses incurred by the Purchasers, and approved by the Company, in connection
with the transactions hereunder and in connection with any amendments or waivers
(whether or not the same become effective) hereof and all reasonable expenses
incurred by the Purchasers in connection with the enforcement of any rights
hereunder or with respect to any Purchased Security, including without
limitation (i) the cost and expenses of preparing and duplicating this
Agreement, each Related Agreement and the Purchased Securities; and (ii) all
Taxes arising from this Agreement or the consummation of the transactions
contemplated herein including, without limitation, any recording fees, filing
fees and documentary stamp and similar Taxes at any time payable in respect of
this Agreement or any Related Agreement or the issuance of any of the Purchased
Securities and any securities issued in exchange therefor provided that the
Company shall not be liable for (i) Taxes determined with respect to income, and
(ii) Taxes


                                       12

<PAGE>

relating to and transfer of the Purchased Securities to any Person other than
the Company.

           SECTION 6.2. INDEMNIFICATION. The Company hereby further agrees to
indemnify, exonerate and hold each Purchaser, its Affiliates and their
investors, and its (if applicable) general and limited partners and their
respective shareholders, officers, directors, employees and agents free and
harmless from and against any and all actions, causes of action, suits, losses,
liabilities, damages and expenses, including, without limitation, reasonable
attorneys' fees and disbursements, incurred in any capacity by any of the
indemnities as a result of or relating to (i) any transaction financed or to be
financed in whole or in part, directly or indirectly, with proceeds from the
sale of any of the Purchased Securities, (ii) the execution, delivery,
performance or enforcement of this Agreement, the Related Agreements or any
agreement, document or instrument contemplated hereby or thereby (including,
without limitation, any failure by the Company to comply with any of the
covenants thereunder), (iii) any breach of any representation or warranty of the
Company in this Agreement or any Related Agreement, (iv) any violation of any
Environmental Laws with respect to conditions at the property now, heretofore or
hereafter owned or used by the Company or any of its Subsidiaries or the
operations conducted thereon, and (v) the investigation or remediation of
offsite locations at which the Company or any of its Subsidiaries or their
predecessors are alleged to have directly or indirectly disposed of Hazardous
Materials.


                                   ARTICLE VII

                                     NOTICES

           Any notices or other communications required to be given pursuant to
this Agreement shall be in writing and shall be deemed given: (i) upon delivery,
if by hand; (ii) three (3) Business Days after mailing, if sent by registered or
certified mail, postage prepaid, return receipt requested; (iii) one (1)
Business Day after mailing, if sent via overnight courier; or (iv) upon
transmission, if sent by telex or facsimile except that if such notice or other
communication is received by telex or facsimile after 5:00 p.m. on a Business
Day at the place of receipt, it shall be effective as of the following Business
Day. All notices and other communications hereunder shall be given as follows:

           (a)  If to the Company, to it at:

                Carrier1 International GmbH
                Militarstrasse 36
                8004 Zurich, Switzerland
                Attention:
                Facsimile: 01/297 26 01
                Telephone: 01/297 26 00


                                       13

<PAGE>

           With a copy to:

                Carrier One, LLC
                901 Fleet Center
                50 Kennedy Plaza
                Providence RI 02903
                Attention:  Glenn M. Creamer
                Facsimile:  (401)751-1790
                Telephone:  (401)751-1700

           (b)  If to Carrier One, to it at:
                901 Fleet Center
                50 Kennedy Plaza
                Providence RI 02903
                Attention:  Glenn M. Creamer
                Facsimile:  (401)751-1790
                Telephone:  (401)751-1700

           (c)  If to other Purchasers, to them at their respective addresses
notified by them to the Company from time to time:

Any party may change its address for receiving notice by written notice given
to the other names above in the manner provided above.

                                  ARTICLE VIII

                       AMENDMENTS, WAIVERS AND ASSIGNMENT

           No modification to or amendment of any provision of this Agreement
shall be effective against the Company, Carrier One or any Purchaser unless such
modification or amendment is approved in writing by the Majority Purchasers and
the Company, except for adding Additional Purchasers to this Agreement and any
consequential amendment to Schedule 2.1 hereto, which amendment may be made in
accordance with Article XII. No waiver of the rights and obligations hereunder
of any party hereto shall be effective unless such waiver is in writing and duly
executed and delivered by (a) the Majority Purchasers (in the event such waiver
is sought by the Company), or (b) the Company (in the event such waiver is
sought by any Purchaser). The failure of any party hereto to enforce any of
provision of this Agreement shall in no way be construed as a waiver of such
provision and shall not affect the right of such party thereafter to enforce
each and every provision of this Agreement in accordance with its terms. Any
amendment or waiver effected in accordance with this Article VIII shall be
binding upon the Company, Carrier One and each Purchaser. The Company
acknowledges and agrees that any Purchaser which is not an individual, upon the
approval of the Majority Purchasers, shall have the right to assign its rights
and obligations hereunder to one or more institutional or venture capital
investors and shall be released from its commitments hereunder to the extent
assigned; provided that Providence Equity Partners L.P. and its affiliates shall
retain, directly or indirectly, sufficient Purchased Securities to be the
Majority Purchasers.


                                       14
<PAGE>

                                   ARTICLE IX

                           GOVERNING LAW; JURISDICTION

           (a) THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE
WITH THE LAWS OF LUXEMBOURG WITHOUT GIVING EFFECT TO ANY CHOICE OR CONFLICT OF
LAW PROVISION OR RULE THAT WOULD CAUSE THE APPLICATION OF THE SUBSTANTIVE LAWS
OF ANY OTHER JURISDICTION, AND SHALL BIND AND INURE TO THE BENEFIT OF THE
PARTIES HERETO AND THEIR RESPECTIVE SUCCESSORS AND ASSIGNS.

           (b) The courts of England have jurisdiction to hear and decide any
suit, action or proceedings, and to settle any disputes, which may arise out of
or in connection with this Agreement (respectively, "PROCEEDINGS" and
"DISPUTES") and for this purpose each party irrevocably submits to the
jurisdiction of the Courts of England.

           (c) Paragraph (b) above does not prevent any party to this Agreement
from taking proceedings relating to Proceedings or Disputes in any other courts
with jurisdiction.

           (d) Each party irrevocably waives any objection which it might at any
time have to the courts of England being nominated as the forum to hear and
decide any Proceedings and to settle any disputes and agrees not to claim that
the courts of England are not a convenient or appropriate forum.

                                    ARTICLE X

                ENTIRE AGREEMENT; COUNTERPARTS; SECTION HEADINGS

           This Agreement, the Purchased Securities and the Related Agreements
set forth the entire understanding of the parties hereto with respect to the
transactions contemplated hereby and supersede any prior written or oral
understandings with respect thereto. This Agreement may be executed
simultaneously in one or more counterparts thereof, each of which shall be
deemed an original but all of which together shall constitute one and the same
instrument. The parties shall execute at least as many copies of this Agreement
as there are parties to this Agreement. The headings in this Agreement are for
convenience of reference only and shall not alter or otherwise affect the
meaning hereof.


                                       15
<PAGE>

                                   ARTICLE XI

                              WAIVER OF JURY TRIAL

           The parties hereto each hereby knowingly, voluntarily and
intentionally waive any rights to have a trial by jury in respect of a
litigation (whether as claim, counterclaim, affirmative defense of otherwise)
in connection with or in any way related to this Agreement.


                                   ARTICLE XII

                              ADDITIONAL PURCHASERS

           The Company may agree to sell additional Equity Securities to any
Person (an "Additional Purchaser") in accordance with the terms of this
Agreement, in which case (i) this Agreement shall be amended to reflect such
Additional Purchaser as Purchaser by a separate letter agreement among Carrier
One, the Company and such Additional Purchaser, and (ii) the representations
given in ARTICLE IV shall be given to the Company by such Additional Purchaser
as at such date of such sale.


                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]


                                       16
<PAGE>

           If the foregoing corresponds with your understanding of our
agreement, kindly sign this letter and the accompanying copies thereof in the
appropriate space below.

                                             VERY TRULY YOURS,


CARRIER ONE, LLC


BY:  /s/ Glenn M. Creamer
   --------------------------------
NAME:  GLENN M. CREAMER
TITLE: CHAIRMAN



ACCEPTED AND AGREED TO:


CARRIER1 INTERNATIONAL S.A.



BY:  /s/ Glenn M. Creamer
   --------------------------------
NAME:  GLENN M. CREAMER
TITLE: CHAIRMAN


                                       17
<PAGE>

                            ACCEPTED AND AGREED TO:


                            /s/ Kees Van Ophem
                            --------------------------
                            KEES VAN OPHEM


               [SIGNATURE PAGE TO SECURITIES PURCHASE AGREEMENT]


                                       18
<PAGE>

                            ACCEPTED AND AGREED TO:


                            /s/ Neil Craven
                            --------------------------
                            NEIL CRAVEN


               [SIGNATURE PAGE TO SECURITIES PURCHASE AGREEMENT]


                                       18
<PAGE>

                            ACCEPTED AND AGREED TO:


                            /s/ Edward Gross
                            --------------------------
                            EDWARD GROSS


               [SIGNATURE PAGE TO SECURITIES PURCHASE AGREEMENT]


                                       18
<PAGE>

                            ACCEPTED AND AGREED TO:


                            /s/ Philip Poulter
                            --------------------------
                            PHILIP POULTER


               [SIGNATURE PAGE TO SECURITIES PURCHASE AGREEMENT]


                                       18
<PAGE>

                            ACCEPTED AND AGREED TO:


                            /s/ Terje Nordahl
                            --------------------------
                            TERJE NORDAHL


               [SIGNATURE PAGE TO SECURITIES PURCHASE AGREEMENT]


                                       18
<PAGE>

                            ACCEPTED AND AGREED TO:


                            /s/ Eugene A. Rizzo
                            --------------------------
                            EUGENE A. RIZZO


               [SIGNATURE PAGE TO SECURITIES PURCHASE AGREEMENT]


                                       18
<PAGE>

                            ACCEPTED AND AGREED TO:


                            /s/ Stig Johansson
                            --------------------------
                            STIG JOHANSSON


               [SIGNATURE PAGE TO SECURITIES PURCHASE AGREEMENT]


                                       18
<PAGE>

                            ACCEPTED AND AGREED TO:


                            /s/ Joachim Bauer
                            --------------------------
                            JOACHIM BAUER


               [SIGNATURE PAGE TO SECURITIES PURCHASE AGREEMENT]


                                       18
<PAGE>

                                  SCHEDULE 2.1

                               LIST OF PURCHASERS
                               ------------------

NAME
- ----
1     Carrier One, LLC/_______Shares

2     Stig Johansson

3     Joachim Bauer

4     Eugene A. Rizzo

5     Kees Van Ophem

6     Neil Craven

7     Terje Nordahl

8     Edward Gross

9     Philip Poulter

10    Alejandra Ancarani

11    Volker Weisshaar

12    Martin Keller

13    Judith Zollinger

14    Jan van Veldhoven

15    Martin Peck

16    Carina Almroth

17    Dieter Friedrich

18    Marc Gauw

19    Ian Cooper

20    Harm Werkman

21    Astrid Werner

22    Vanja Vidic

23    Peter Gessler

24    Matthias Neumann

25    Christoph Mees

26    Nigel Findlater

27    Christopher Davison
<PAGE>

28    Gustav Schaefer

29    Teunis Florus Oskam

30    Jonathan Shanmuganathan

31    Kasim Sheikh

32    Jane Townend

33    Isabelle Russier

34    Antonia Keller

35    Rob Hale

36    Linda Clark

37    Gertfried Uitz

38    Philip Walter

39    Dominic McGlinchey

40    Heinz Bigler

41    Evelien Aalberts

42    Rick Mikolajczuk


<PAGE>

                                                                   Exhibit 10.13


                          REGISTRATION RIGHTS AGREEMENT

                                  By and Among

                                CARRIER ONE, LLC
                                 STIG JOHANSSON,
                                 JOACHIM BAUER,
                                EUGENE A. RIZZO,
                                 KEES VAN OPHEM,
                                  NEIL CRAVEN,
                                 TERJE NORDAHL,
                                  EDWARD GROSS,
                                 PHILIP POULTER

                                       and

                           CARRIER1 INTERNATIONAL S.A.


                              Dated as of March 1,
                                      1999




<PAGE>

                               Table of Contents
                               -----------------


1.    Demand Registrations.....................................................1

2.    Piggyback Registrations..................................................3

3.    Holdback Agreements......................................................6

4.    Other Public Offers; Registration and Public Offer Procedures............6

5.    Registration Expenses...................................................10

6.    Indemnification.........................................................11

7.    Participation in Underwritten Registrations.............................15

8.    Rule 144 Reporting......................................................15

9.    Definitions.............................................................16

10.   Miscellaneous...........................................................18


<PAGE>

           This Registration Rights Agreement is made as of March 1, 1999, by
and among Carrier1 International S.A., a Luxembourg SOCIETE ANONYME (the
"Company"), Carrier One, LLC, a Delaware limited liability company ("Carrier
One"), and Stig Johansson ("Johansson"), Joachim Bauer ("Bauer"), Eugene A.
Rizzo ("Rizzo"), Kees Van Ophem ("Van Ophem"), Neil Craven ("Craven"), Terje
Nordahl ("Nordahl"), Edward Gross ("Gross") and Philip Poulter ("Poulter"), and
together with Johansson, Bauer, Rizzo, Van Ophem, Craven, Nordahl, Gross and
Poulter the "Management Investors"). Capitalized terms used herein but not
otherwise defined herein or in Section 9 hereof shall have the meanings ascribed
thereto in the "Securities Purchase Agreement" (as defined below).

                                   WITNESSETH:

           WHEREAS, LLC and the Management Investors hold securities issued by
the Company, subject to the provisions of the Securityholders Agreement, dated
as of the date hereof, among the Company, the Management Investors and LLC;

           WHEREAS, the Company, Carrier One and the Management Investors
anticipate that equity securities of the Company (or American depositary
receipts or shares representing interests in such securities) will eventually be
offered by means of an underwritten public offering within the United States
possibly in connection with a listing on the New York Stock Exchange or another
exchange in the United States, as well as by public or private offerings outside
the United States;

           WHEREAS, the Company, Carrier One and the Management Investors wish
to provide for certain registration and other rights with respect to the
securities of the Company;

           NOW, THEREFORE, in consideration of the mutual covenants contained
herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties to this Agreement,
intending to be legally bound, hereby agree as follows:

           1. DEMAND REGISTRATIONS. (a) REQUEST FOR REGISTRATION. (i) At any
time after the earlier to occur of (x) March 1, 1999 and (y) six (6) months
after the closing of an IPO, Carrier One may request registration under the
Securities Act of 1933, as amended (the "Securities Act"), of (A) all or any
portion of Carrier One's Registrable Securities on Form S-1 or any similar
long-form registration (each a "Long-Form Registration"), and (B) all or any
portion of Carrier One's Registrable Securities on Form S-3 (including pursuant
to Rule 415 under the Securities Act) or any similar short-form registration
(each a "Short-Form Registration") if available as provided hereinafter. All
registrations requested pursuant to this SECTION 1(A) are referred to herein as
"Demand Registrations". Each request for a Demand Registration shall specify the
number of Registrable Securities requested to be registered for such offering.


<PAGE>

           (b) LONG-FORM REGISTRATIONS. Carrier One shall be entitled to request
four (4) Long-Form Registrations; PROVIDED, HOWEVER, that the Company shall not
be obligated to effect a Long-Form Registration pursuant to this Section 1(b) if
the anticipated aggregate offering price of the Registrable Securities to be
sold is less than $10 million. The Company shall pay all Registration Expenses
with respect to each Long-Form Registration. A registration shall not count as
one of the permitted Long-Form Registrations until it has become effective and
Carrier One is able to register and sell at least 90% of the Registrable
Securities requested to be included in such registration by Carrier One;
PROVIDED THAT in any event the Company shall pay all Registration Expenses in
connection with any registration initiated as Long-Form Registration regardless
of whether it has become effective. All Long-Form Registrations shall be
underwritten registrations.

           (c) SHORT-FORM REGISTRATIONS. In addition to the Long-Form
Registrations provided pursuant to SECTION 1(B), Carrier One shall be entitled
to request up to three (3) Short-Form Registrations per year in which the
Company shall pay all Registration Expenses; PROVIDED, HOWEVER, that the Company
shall not be obligated to effect a Short-Form Registration pursuant to this
SECTION 1(C) if the anticipated aggregate offering price of the Registrable
Securities to be sold is less than $5.0 million or if Carrier One has made a
request for a Short-Form Registration which has become effective within the
prior 180 days. Notwithstanding anything contained herein to the contrary,
Demand Registrations shall be Short-Form Registrations whenever the Company is
permitted to use any applicable short form. The Company shall use its best
efforts to make Short-Form Registrations on Form S-3 available for the sale of
Registrable Securities after the Company has become subject to the reporting
requirement of the Securities Exchange Act of 1934, as amended (the "Securities
Exchange Act"). If the Company is qualified to and, pursuant to the request of
an Institutional Investor, has filed with the Securities and Exchange Commission
(the "Commission") a registration statement under the Securities Act on Form S-3
pursuant to Rule 415 under the Securities Act (the "Required Registration"), the
Company shall use its best efforts to cause the Required Registration to be
declared effective under the Securities Act as soon as practicable after filing,
and once effective, the Company shall cause such Required Registration to remain
effective for a period ending on the earlier of (i) 180 days after the effective
date, or (ii) the date on which all Registrable Securities held by Carrier One
and included in such Required Registration have been sold pursuant to the
Required Registration (the "Effective Period").

           (d) PRIORITY ON DEMAND REGISTRATIONS. The Company shall not include
in any Demand Registration any Equity Securities which are not Registrable
Securities without the prior written consent of Carrier One. If the managing
underwriters advise the Company and Carrier One in writing that in their opinion
the number of Registrable Securities to be included in an underwritten offering
exceeds the number of Registrable Securities which can be sold in an orderly
manner in such offering within a price range


                                       2

<PAGE>

acceptable to Carrier One or marketing factors require a limitation on the
number of Registrable Securities to be underwritten on behalf of the Company,
then the Company shall include in such registration prior to the inclusion of
any Equity Securities which are not Registrable Securities, the number of
Registrable Securities requested to be included which in the opinion of such
underwriters can be sold in (or during the time of such offering without such
interference or affect on the price (the "Demand Registration Cutback") as
follows: FIRST the Registrable Securities requested to be included by Carrier
One; and SECOND the Equity Securities proposed to be sold by the Company for its
own account or any other holder of Equity Securities.

           (e) RESTRICTIONS ON DEMAND REGISTRATIONS. The Company shall not be
obligated to effect any Demand Registration within 180 days after the effective
date of a previous Demand Registration. The Company shall be entitled to
postpone, for a reasonable period of time not in excess of 90 days after its
receipt of an initial request for a Demand Registration pursuant to this
Agreement, the filing of any registration statement if at the time it received
such request, the Board determines, in its reasonable business judgment, that
such registration and offering would be reasonably expected to have an adverse
effect on any financing, acquisition, corporate reorganization or other material
transaction or development involving the Company PROVIDED THAT the Company shall
only be entitled to one such postponement in any 12-month period. The Company
shall give Carrier One prompt written notice of such postponement. In the event
of such postponement, the Company shall comply with such request for Demand
Registration as soon as practicable (and in any event within 90 days after its
receipt of the initial request for such Demand Registration) after it shall
determine, in its reasonable business judgment, that such registration and
offering will not interfere with the matters described in the second sentence of
this SECTION 1(E). If the Company shall postpone the filing of any registration
statement, Carrier One shall have the right to withdraw its request for such
registration by giving notice to the Company. In the event that Carrier One
withdraws its request in the foregoing manner, such request shall not be counted
for purposes of determining the number of registrations to which Carrier One is
entitled pursuant to SECTION 1.

           (f) SELECTION OF UNDERWRITERS. Carrier One will have the right to
select the investment banker(s) and manager(s) to administer any offering
including Registrable Securities held by Carrier One (which, if necessary will
include a "qualified independent underwriter" within the meaning of the rules of
the National Association of Securities Dealers, Inc. (a "QIU")), subject to the
Company's approval which will not be unreasonably withheld.

           2. PIGGYBACK REGISTRATIONS. (a) RIGHT TO PIGGYBACK. Whenever the
Company proposes to register any of its Equity Securities (including any
proposed registration of the Company's Equity Securities by any third party)
under the Securities Act whether or not for sale for its own account (other than
pursuant to a Demand Registration or a registration on Form S-4 or S-8 or any
successor or similar forms, but including an IPO)


                                       3

<PAGE>

and the registration form to be used may be used for the registration of
Registrable Securities held by Carrier One or any Management Investor (a
"Piggyback Registration"), the Company shall give prompt written notice to
Carrier One and the Management Investors of its intention to effect such a
registration and shall include in such registration, subject TO SECTIONS 2(C)
and (D), all Registrable Securities held by Carrier One and, subject to the
provisions of the Securityholders Agreement, all Registrable Securities of the
Management Investors with respect to which the Company has received written
requests for inclusion therein within ten (10) business days after the receipt
of the Company's notice; provided in no event shall any Management Investor have
the right of Piggyback Registration in connection with an IPO.

           (b) PIGGYBACK EXPENSES. The Registration Expenses of Carrier One and
the Management Investors shall be paid by the Company in all Piggyback
Registrations.

           (c) PRIORITY ON PRIMARY REGISTRATIONS. If a Piggyback Registration is
an underwritten primary registration on behalf of the Company, and the managing
underwriters advise the Company, Carrier one and each Management Investor
requesting registration in writing that in their opinion the number of Equity
Securities that holders of Equities Securities propose to sell therein, whether
or not such selling holders have the right to include Equity Securities therein
(the "Other Equity Securities"), plus the number of Warrant Shares that holders
thereof have requested to be sold therein, plus the number of Equity Securities
to be underwritten on behalf of the Company (the "Company Equity Securities"),
exceeds the maximum number of Equity Securities specified by the managing
underwriters that may be distributed without adversely affecting the price,
timing or distribution of the Company Equity Securities, then the Company shall
include in such registration such maximum number of Equity Securities requested
to be included as follows: FIRST the Company Equity Securities, SECOND the
Registrable Securities requested to be included in such registration by Carrier
One, THIRD the Equity Securities requested to be included in such registration
by the Management Investors and, if applicable, the Other Management Investors,
pro rata among the Management Investors and, if applicable, the Other Management
Investors on the basis of the Registrable Securities owned by each such holder,
and FOURTH the Equity Securities requested to be included in such registration
by any other holder.

           (d) PRIORITY ON SECONDARY REGISTRATIONS. If a Piggyback Registration
is entirely an underwritten secondary registration on behalf of holders of the
Company's securities, and the managing underwriters advise the Company, Carrier
One and each Management Investor or other Management Investor requesting
registration in writing that in their opinion the number of Warrant Shares and
Other Equity Securities to be included in such offering exceeds the maximum
number of Equity Securities (the "Includible Secondary Securities") specified by
the managing underwriter that may be distributed without adversely affecting the
price, timing or distribution of the Equity Securities being distributed, then:


                                       4

<PAGE>

           (i) in the case of a demand registration pursuant to this Agreement,
      FIRST each party exercising such demand registration rights and Carrier
      One, SECOND each other Permitted Holder, Management Investor, Other
      Management Investor or Beneficial Investor from time to time party to or
      beneficiary of this Agreement, and THIRD each requesting holder of Warrant
      Shares, together with each other party exercising its registration rights
      under this Agreement, shall, in that order of priority, be entitled to
      include up to its pro rata portion of the Includible Secondary Securities
      remaining after inclusion of the Includible Secondary Securities of any
      holder having priority and in priority to the inclusion of any Other
      Equity Securities, other than as specified above, that are proposed to be
      sold in such public offering;

           (ii) in the case of any other demand registration, FIRST each party
      exercising such demand registration rights shall be entitled to include
      all of its Includible Secondary Shares, then each requesting holder of
      Warrant Shares, together with Carrier One and each Permitted Holder,
      Management Investor, Other Management Investor or Beneficial Investor from
      time to time party to or beneficiary of this Agreement, shall be entitled
      to include up to its pro rata portion of the remaining Includible
      Secondary Securities and in priority to the inclusion of any Other Equity
      Securities other than as specified above, that are proposed to be sold in
      such public offering.

           (e)  SELECTION OF UNDERWRITERS.  If any Piggyback Registration is an
underwritten offering, the selection of investment banker(s) and manager(s) for
the offering (which, if necessary, will include a QIU) must be approved by
Carrier One.

           (f) OTHER REGISTRATIONS. If the Company has previously filed a
registration statement with respect to Registrable Securities pursuant to
SECTION 1 or pursuant to this SECTION 2, and if such previous registration has
not been withdrawn or abandoned, the Company shall not file or cause to be
effected any other registration of any of its Equity Securities under the
Securities Act (except on Form S-8 or any successor form), whether on its own
behalf or at the request of any holder or holders of such securities, until a
period of at least 180 days has elapsed from the effective date of such previous
registration.

           (g) OTHER EMPLOYEES. Upon request of any Management Investor who is
also a member of the Board of Directors or the Chief Executive Officer of the
Company, the Company shall make available to each other director or employee of
the Company or any of its Affiliates (the "Other Management Investors") holding
Equity Securities of the Company who is also a party to the Securityholders'
Agreement the rights afforded to the Management Investors under Sections 2 and 4
of this Agreement, subject to such Other Management Investor agreeing in writing
to abide by all of the terms and conditions of this Agreement applicable to
Management Investors as if such employee were a Management Investor, MUTATIS
MULANDIS, including without limitation the obligations of Management Investors
under Section 3 of this Agreement. For the avoidance of doubt,


                                       5

<PAGE>

no consent of any such Other Management Investor shall be required to amend or
waive any provision of, or to terminate, this Agreement.

           3. HOLDBACK AGREEMENTS. (a) If requested in writing by the
underwriters for the IPO or any other Public Offer of Equity Securities of the
Company, Carrier One and each Management Investor shall agree not to effect any
public sale or public transfer (including sales pursuant to Rule 144 or
Regulation S) of Equity Securities during a period of not more than 190 days
beginning on the effective date of the registration statement relating to such
IPO, in the case of a public offering in the United States, or beginning on the
date the offering is closed, in the case of any other Public Offer outside the
United States; PROVIDED, HOWEVER, that all Persons entitled to registration
rights with respect to Equity Securities of the Company who are not parties to
this Agreement, all Persons holding in excess of five percent (5%) of the
capital stock of the Company on a fully diluted basis and all executive officers
and directors of the Company shall have also agreed not to sell publicly or
transfer their Equity Securities under the terms set forth in this Section 3
(a).

           (b) The Company (i) agrees not to effect any public sale or
distribution of its Equity Securities during the 10 days prior to and during the
180-day period beginning on the effective date of any (u) underwritten Demand
Registration, (v) underwritten Piggyback Registration (except as part of such
underwritten registration or pursuant to a registration on Form S-8 or any
successor form), (w) post-effective amendment of a Required Registration
pursuant to which an underwritten offering is to be effected so long as at least
180 days have elapsed since the end of the previous lock-up period pursuant to
this clause (w) unless (in any such case) the underwriter managing the
registered public offering otherwise agrees, or (x) preliminary or final
prospectus, offering memorandum or circular or other offering document in
respect of any other Public Offer of Equity Securities and (ii) agrees to cause
each holder of its Equity Securities purchased from the Company at any time
after the date of this Agreement (other than in a registered public offering) to
agree not to effect any public sale or distribution (including sales pursuant to
Rule 144 or Regulation S) of any such securities during such period (except as
part of such underwritten registration, if otherwise permitted, and, in the case
of an underwritten Piggyback Registration, as part of such underwritten
registration or pursuant to a registration on Form S-8 or any successor form),
unless the underwriters managing the registered public offering otherwise agree.

           4. OTHER PUBLIC OFFERS; REGISTRATION AND PUBLIC OFFER PROCEDURES.
Prior to, concurrently with or following a US Public Offer, Carrier One may
determine to proceed United States and possibly concurrent private offerings of
Equity Securities within and outside the United States, to the extent permitted
by applicable law, accompanied by listings on one or more exchanges or
over-the-counter markets and applications for qualification of Equity Securities
to be traded on SEAQ International, PORTAL or a similar system. If at any time
after March 1, 1999 Carrier One so requests, the Company


                                       6

<PAGE>

and the Management Investors shall co-operate with Carrier One and take such
measures as may be necessary in the reasonable judgment of Carrier One
(including, in the case of the Management Investors, voting their Equity
Securities) in order to permit such offerings to be completed and such related
actions to be taken in compliance with all applicable laws and regulations and
the rules of any exchange in which the Equity Securities are or are to be
listed, including any of the measures listed in Section 4 or any comparable
measures applicable to such offerings and related actions. It is the parties'
intention that the respective rights and obligations of the Company, Carrier One
and the Management Investors with respect to such offerings shall be equivalent,
insofar as legally permitted and reasonably practicable in light of the
customary market practice applicable to such offerings, to those set forth in
this Agreement with respect to registration of Registrable Securities in the
U.S., and that, if any such offering is proposed by Carrier One, the parties
shall negotiate in good faith such amendments to this Agreement as Carrier One
may reasonably request to better define such rights and obligations in such
connection. Whenever Carrier One or a Management Investor shall have requested
that any Registrable Securities be registered in accordance with Section 1 or 2
of this Agreement or otherwise offered by means of a Public Offer, the Company
shall,

           (I) in the case of a US Public Offer use its best efforts to effect
the registration and the sale of such Registrable Securities in accordance with
the intended method of disposition thereof, and pursuant thereto the Company
shall as expeditiously as possible:

           (a) prepare and file with the Commission a registration statement
with respect to such Registrable Securities and use its best efforts to cause
such registration statement to become effective (provided that within a
reasonable time before filing a registration statement or prospectus or any
amendments or supplements thereto, the Company shall furnish to counsel selected
by Carrier One and the Management Investors participating in such registration
copies of all such documents proposed to be filed, which documents shall be
subject to the review and comment of such counsel);

           (b) notify in writing Carrier One and each Management Investor
requesting registration of its Registrable Securities of the effectiveness of
each registration statement filed hereunder and prepare and file with the
Commission such amendments and supplements to such registration statement and
the prospectus used in connection therewith as may be necessary to keep such
registration statement effective for a period of either (i) not less than 180
days or such longer period specified in SECTION 1(C) (subject to extension
pursuant to SECTION 7(B)), or, if such registration statement relates to an
underwritten offering, such longer period as (in the opinion of counsel for the
underwriters) a prospectus is required by law to be delivered in connection with
sales of Registrable Securities by an underwriter or dealer, or (ii) such
shorter period as will terminate when all of the securities covered by such
registration statement during such period have been disposed of in accordance
with the intended methods of disposition by


                                       7

<PAGE>

the seller or sellers thereof set forth in such registration statement (but in
any event not before the expiration of any longer period required under the
Securities Act), and to comply with the provisions of the Securities Act with
respect to the disposition of all securities covered by such registration
statement until such time as all of such securities have been disposed of in
accordance with the intended methods of disposition by the seller or sellers
thereof set forth in such registration statement subject to the time limits set
forth herein;

           (c) furnish to Carrier One and each Management Investor requesting
registration of its Registrable Securities such number of copies of such
registration statement, each amendment and supplement thereto, the prospectus
included in such registration statement (including each preliminary prospectus)
and such other documents as such Institutional Investor or Management Investor
may reasonably request in order to facilitate the disposition of its Registrable
Securities;

           (II) in the case of a US Public Offer or any other Public Offer:

           (a) use its best efforts to register or qualify such Registrable
Securities under such other securities or blue sky laws of such jurisdictions as
Carrier One or such Management Investor reasonably requests and do any and all
other acts and things which may be reasonably necessary or advisable to enable
Carrier One or any Management Investor to consummate the disposition in such
jurisdictions of the Registrable Securities owned by Carrier One or such
Management Investor (provided that the Company shall not be required to (i)
qualify generally to do business in any jurisdiction where it would not
otherwise be required to qualify but for this subparagraph, (ii) subject itself
to taxation in any such jurisdiction, or (iii) consent to general service or
process in any such jurisdiction);

           (b) notify Carrier One and each Management Investor requesting
registration of its Registrable Securities or inclusion thereof in a Public
Offer, at any time when a prospectus, offering circular or memorandum or other
offering document relating thereto is required to be delivered under the
Securities Act or other applicable law, upon discovery that, or upon the
discovery of the happening of any event as a result of which the prospectus or
such other document contains an untrue statement of a material fact or omits any
fact necessary to make the statements therein not misleading in the light of the
circumstances under which they were made, and, at the request of Carrier One or
any Management Investor, the Company shall promptly furnish to Carrier One or
such Management Investor, as the case may be, a reasonable number of copies of a
supplement or amendment to such prospectus so that, as thereafter delivered to
the purchasers of such Registrable Securities, such prospectus or other document
shall not contain an untrue statement of a material fact or omit to state any
fact necessary to make the statements therein not misleading in the light of the
circumstances under which they were made;


                                       8

<PAGE>

           (c) cause all such Registrable Securities to be listed on each
securities exchange on which similar securities issued by the Company are then
listed;

           (d) provide a transfer agent and registrar for all such Registrable
Securities and a CUSIP number for all such Registrable Securities not later then
the effective date of such registration statement;

           (e) enter into such customary agreements and depositary or custodial
arrangements (including underwriting and deposit agreements in customary form)
and take all such other actions as Carrier One and any Management Investors
participating in such registration or the underwriters, if any, reasonably
request in order to expedite or facilitate the disposition of the Registrable
Securities being sold;

           (f) make available for inspection by Carrier One or any Management
Investor requesting inclusion of its Registrable Securities in such Public Offer
or other Public Offer, any participating underwriter and any attorney,
accountant or other agent retained by Carrier One, such Management Investor or
underwriter, all financial and other records, pertinent corporate documents and
properties of the Company, and cause the Company's officers, directors,
employees and independent accountants to supply all information reasonably
requested by Carrier One, such Management Investor, underwriter, attorney,
accountant or agent in connection with such registration statement and assist
and, at the request of any participating underwriter, cause such officers or
directors to participate in presentations to prospective purchasers;

           (g) otherwise use its best efforts to comply with all applicable
rules and regulations of the Commission or any comparable authority in any
foreign jurisdiction and any exchange on which Equity Securities are or are to
be listed, . and make available to its Securityholders, as soon as reasonably
practicable, an earnings statement covering the period of at least twelve months
beginning with the first day of the Company's first full calendar quarter after
the effective date of the registration statement, which earnings statement shall
satisfy the provisions of Section 11 (a) of the Securities Act and Rule 158
thereunder or, in the case of a Public Offer which is not a US Public Offer, any
other financial statements or data of the Company which may be required to be
provided by applicable law or the rules and regulations of any such non-U.S.
authority or exchange?

           (h) permit any holder of Registrable Securities, which holder might
be deemed to be an underwriter or a controlling person of the Company, to
participate in the preparation of such registration or comparable statement or
prospectus, offering circular or memorandum or other offering document and to
require the insertion therein of material, furnished to the Company in writing,
which in the reasonable judgment of such holder and its counsel should be
included;


                                       9

<PAGE>

           (i) in the event of the issuance of any stop order suspending the
effectiveness of a registration statement, of any order suspending or preventing
the use of any prospectus, offering circular or memorandum or other offering
document or suspending the qualification of any securities included in such
registration statement or other document for sale or trading in any
jurisdiction, use its best efforts promptly to obtain the withdrawal of such
order;

           (j) use its best efforts to cause any such registration statement,
prospectus, offering circular or memorandum or other offering document and, if
required, Registrable Securities covered by such registration statement or other
document to be registered with, qualified or approved by such other Governmental
Authorities or exchanges on which Equity Securities of the Company are or are to
be listed as may be necessary to enable Carrier One and the Management Investors
to consummate the disposition of their Registrable Securities;

           (k) obtain one or more comfort letters, dated the effective date of
such registration statement (and, if such registration includes an underwritten
public offering, dated the date of the closing under the underwriting agreement,
final prospectus, offering circular or memorandum or other offering document),
from the Company's independent public accountants in customary form and covering
such matters of the type customarily covered by comfort letters as Carrier One
reasonably requests; and

           (l) use reasonable efforts to cause certificates for the Registrable
Securities covered by such registration statement, final prospectus, offering
circular or memorandum or other offering document to be delivered by the holders
thereof to the underwriters in such denominations and registered in such names
as the underwriters may request.

           5. REGISTRATION EXPENSES. (a) All expenses incident to the Company's
performance of or compliance with this Agreement, including, without limitation,
all registration and filing fees, listing fees, fees and expenses of compliance
with securities or blue sky laws, printing expenses, travel expenses, filing
expenses, messenger and delivery expenses, fees and disbursements of custodians,
depositories, fees and disbursements of counsel of the Company and fees and
disbursements of all independent certified public accountants, underwriters
including, if necessary, a QIU (excluding discounts and commissions) and other
Persons retained by the Company, Carrier One or the Management Investors (all
such expenses being herein called "Registration Expenses") shall be borne and
paid by the Company. The Company shall, in any event, pay its internal expenses
(including, without limitation, all salaries and expenses of its officers and
employees performing legal or accounting duties), the expense of any annual
audit or quarterly review, the expense of any liability insurance and the
expenses and fees for listing the securities to be registered on each securities
exchange on which similar


                                       10

<PAGE>

securities issued by the Company are then listed or on the NASD automated
quotation system (or any successor or similar system).

           (b) In connection with each Demand Registration and each Piggyback
Registration (or comparable proceeding with respect to a Public Offer outside
the U.S.), the Company shall reimburse Carrier One the reasonable fees and
disbursements of (i) one special counsel for Carrier One, and (ii) its local
counsel.

           (c) In connection with each Demand Registration and each Piggyback
Registration (or comparable proceeding with respect to a Public Offer outside
the U.S.), Carrier One shall bear and pay all underwriting discounts and
selling commissions applicable to the sale of its Registrable Securities
included in such registration or Public Offer. In connection with each
Piggyback Registration (or comparable proceeding), the Management Investors
shall bear and pay all underwriting discounts and selling commissions
applicable to the sale of their Registrable Securities included in such
registration (or Public Offer).

           6. INDEMNIFICATION. (a) The Company agrees to indemnify and hold
harmless, to the fullest extent permitted by law, Carrier One and its
affiliates, its and their respective officers, directors, agents and employees
and each Person who controls Carrier One or any of its affiliates (within the
meaning of the Securities Act) and each Management Investor against any losses,
claims, damages, liabilities, joint or several, together with reasonable costs
and expenses (including reasonable attorney's fees), to which such indemnified
party may become subject under the Securities Act or otherwise, insofar as such
losses, claims, damages or liabilities (or actions or proceedings, whether
commenced or threatened, in respect thereof) arise out of or are based upon (i)
any untrue or alleged untrue statement of material fact contained (A) in any
registration statement preliminary or final prospectus, offering circular or
memorandum or other offering document for any Public Offer or any amendment
thereof or supplement thereto, or (B) in any application or other document or
communication (in this SECTION 6 collectively called an "application") executed
by or on behalf of the Company or based upon written information furnished by or
on behalf of the Company filed in any jurisdiction in order to qualify any
securities covered by such registration statement or to obtain approval of any
preliminary or final prospectus, offering circular or memorandum or other
offering document under the "blue sky" or other securities laws or listing
regulations thereof, or (ii) any omission or alleged omission of a material fact
required to be stated therein or necessary to make the statements therein not
misleading, and the Company will reimburse Carrier One, each such director,
officer and controlling Person and each Management Investor for any legal or any
other expenses incurred by them in connection with investigating or defending
any such loss, claim, liability, action or proceeding; PROVIDED, HOWEVER, that
the Company shall not be liable in any such case to the extent that any such
loss, claim, damage, liability (or action or proceeding in respect thereof) or
expense arises out of or is based upon an untrue statement or alleged untrue
statement, or omission or alleged omission, made in such registration statement,
any such


                                       11

<PAGE>

preliminary or final prospectus or offering circular or memorandum or other
offering document or any amendment or supplement thereto, or in any
application, in reliance upon, and in conformity with, written information
prepared and furnished to the Company by Carrier One or such Management
Investor, as the case may be, expressly for use therein or by Carrier One or
the Management Investor's, failure, as the case may be, to deliver a copy of
the registration statement, prospectus, offering circular or memorandum or
comparable document or any amendments or supplements thereto after the
Company has furnished Carrier One and such Management Investor with a
sufficient number of copies of the same. In connection with an underwritten
offering, the Company will indemnify such underwriters, their officers and
directors and each Person who controls such underwriters (within the meaning
of the Securities Act) to the same extent as provided above with respect to
the indemnification of an Carrier One and a Management Investor.

           (b) In connection with any registration statement or the preparation
of any preliminary or final prospectus, offering circular or memorandum or other
offering document for a Public Offer in which Carrier One or a Management
Investor is participating, Carrier One and such Management Investor, as the case
may be, will furnish to the Company in writing such information and affidavits
as the Company reasonably requests (and is customarily provided by selling
stockholders) for use in connection with any such registration statement,
prospectus offering circular or memorandum or other offering document and, to
the fullest extent permitted by law, will indemnify and hold harmless the
Carrier One, its affiliates and the other Management Investors holding
Registrable Securities and the Company, and their respective directors,
officers, agents and employees and each other Person who controls the Company
(within the meaning of the Securities Act) against any losses, claims, damages,
liabilities, joint or several, together with reasonable costs and expenses
(including reasonable attorney's fees), to which such indemnified party may
become subject under the Securities Act or otherwise, insofar as such losses,
claims, damages or liabilities (or actions or proceedings, whether commenced or
threatened, in respect thereof) arise out of or are based upon (i) any untrue or
alleged untrue statement of material fact contained in the registration
statement, preliminary or final prospectus, offering circular or memorandum or
other offering document or any amendment thereof or supplement thereto or in any
application, or (ii) any omission or alleged omission of a material fact
required to be stated therein or necessary to make the statements therein not
misleading, but only to the extent that such untrue statement or omission is
made in such registration statement, any such prospectus or offering circular or
memorandum or other offering document or any amendment or supplement thereto, or
in any application, or reliance upon and in conformity with written information
prepared and furnished to the Company by the Carrier One, or Management
Investors, expressly for use therein, and Carrier One, or such Management
Investors, as the case may be, will reimburse the Company and each such other
indemnified party for any legal or any other expenses incurred by them in
connection with investigating or defending any such loss, claim, liability,
action or


                                       12

<PAGE>

proceeding; PROVIDED, HOWEVER, that the obligation to indemnify will be
individual to Carrier One, or such Management Investor, as the case may be, and
will be limited to the net amount of proceeds received by Carrier One or each
Management Investor from the sale of its Registrable Securities pursuant to such
registration statement or in such Public Offer.

           (c) Any Person entitled to indemnification under this Agreement shall
notify promptly the indemnifying party in writing of the commencement of any
action or proceeding with respect to which a claim for indemnification may be
made pursuant to this SECTION 6, but the failure of any indemnified party to
provide such notice shall not relieve the indemnifying party of its obligations
under the preceding subparagraphs of this SECTION 6, except to the extent, but
only to the extent to which, the indemnifying party is materially prejudiced
thereby and shall not relieve the indemnifying party from any liability which it
may have to any indemnified party otherwise than under this SECTION 6. In case
any action or proceeding is brought against an indemnified party and it shall
notify the indemnifying party of the commencement thereof, the indemnifying
party shall be entitled to participate therein and, unless in the reasonable
opinion of outside counsel to the indemnified party a conflict of interest
between such indemnified and indemnifying parties may exist in respect of such
claim, to assume the defense thereof jointly with any other indemnifying party
similarly notified, to the extent that it chooses, with counsel reasonably
satisfactory to such indemnified party, and after notice from the indemnifying
party to such indemnified party that it so chooses, the indemnifying party shall
not be liable to such indemnified party for any legal or other expenses
subsequently incurred by such indemnified party in connection with the defense
thereof other than reasonable costs of investigation; PROVIDED, HOWEVER, that
(i) if the indemnifying party fails to take reasonable steps necessary to defend
diligently the action or proceeding within 20 days after receiving notice from
such indemnified party that the indemnified party believes it has failed to do
so, or (ii) if such indemnifying party reasonably shall have concluded that
there may be one or more legal defenses available to such indemnified party
which are not available to the indemnifying party; or (iii) if representation of
both parties by the same counsel is otherwise inappropriate under applicable
standards of professional conduct, then, in any such case, the indemnified party
shall have the right to assume or continue its own defense as set forth above
(but with no more than one firm of counsel for all indemnified parties in each
jurisdiction, except to the extent any indemnified party or parties reasonably
shall have concluded that there may be legal defenses available to such party or
parties which are not available to the other indemnified parties or to the
extent representation of all indemnified parties by the same counsel is
otherwise inappropriate under applicable standards of professional conduct) and
the indemnifying party shall be liable for any expenses therefor.

           (d) No indemnifying party shall, without the written consent of each
indemnified party (which consent shall not be unreasonably withheld), effect the
settlement or compromise of, or consent to the entry of any judgment with
respect to, any


                                       13

<PAGE>

pending or threatened action or claim in respect of which indemnification or
contribution may be sought hereunder (whether or not the indemnified party is an
actual or potential party to such action or claim) unless such settlement,
compromise or judgment (A) includes an unconditional release of the indemnified
party from all liability arising out of such action or claim without any payment
or consideration provided or obligation incurred by any indemnified party, and
(B) does not include a statement as to or an admission of fault, culpability or
a failure to act, by or on behalf of any indemnified party.

           (e) If the indemnification provided for in this Section 6 is
unavailable to or is insufficient to hold harmless an indemnified party under
the provisions above in respect to any losses, claims, damages, or liabilities
referred to therein, then each indemnifying party shall contribute to the amount
paid or payable by such indemnified party as a result of such losses, claims,
damages or liabilities (i) in such proportion as is appropriate to reflect the
relative fault of the Company, the members of Carrier One and Management
Investors participating in the registration statement, or (ii) if the allocation
provided by clause (i) above is not permitted by applicable law, in such
proportion as is appropriate to reflect not only the relative fault referred to
in clause (i) above but also the relative benefit of the Company, the members of
Carrier One and each Management Investor participating in the registration
statement or the Public Offer in connection with the statement or omissions
which resulted in such losses, claims, damages or liabilities, as well as any
other relevant equitable considerations. The relative benefits received by the
Company, each member of Carrier One and each Management Investor participating
in the registration statement or the Public Offer shall be deemed to be in the
same proportion as the total net proceeds from the offering (before deducting
expenses) received and retained by each such participating party bear to the
total net proceeds from the offering (before deducting expenses). The relative
fault of the Company, each member of Carrier One and each Management Investor
participating in the registration statement or the Public Offer shall be
determined by reference to, among other things, whether the untrue or alleged
omission to state a material fact relates to information supplied by the
Company, a member of Carrier One or a Management Investor participating in the
registration statement or the Public Offer and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
statement or omission.

           The Company, Carrier One and the Management Investors agree that it
would not be just and equitable if contribution pursuant to this Section 6 were
determined by pro rata allocation or by any other method of allocation which
does not take account of the equitable considerations referred to in the
immediately preceding paragraph. The amount paid or payable by an indemnified
party as a result of the losses, claims, damages and liabilities referred to in
the immediately preceding paragraph shall be deemed to include, subject to the
limitations set forth above, any legal or other expenses reasonably incurred by
such indemnified party in connection with investigating or defending any such
action


                                       14

<PAGE>

or claim. Notwithstanding the provisions of this SECTION 6, neither Carrier One
nor any Management Investor shall be required to contribute pursuant to this
SECTION 6 any amount in excess of the sum of (i) any amounts paid pursuant to
SECTION 6(b) and (ii) net proceeds received and retained by Carrier One or the
Management Investor from the sale of its Registrable Securities covered by the
registration statement filed pursuant hereto or otherwise included in a Public
Offer, it being understood that insofar as such net proceeds have been
distributed by Carrier One to its members, the amount of Carrier One's
contribution hereunder shall be limited to the net proceeds which it actually
recovers from its members based upon their relative fault and that to the extent
that Carrier One has not distributed such net proceeds, the amount of Carrier
One's contribution hereunder shall be limited by the percentage of such net
proceeds which corresponds to the percentage equity interests in Carrier One
held by those of its members who have been determined to be at fault. No person
guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of
the Securities Act) shall be entitled to contribution from any Person who was
not guilty of such fraudulent misrepresentations.

           (f) The indemnification and contribution by any such party provided
for under this Agreement shall be in addition to any other rights to
indemnification or contribution which any indemnified party may have pursuant to
law or contract and will remain in full force and effect regardless of any
investigation made or omitted by or on behalf of the indemnified party or any
officer, director or controlling Person of such indemnified party and will
survive the transfer of securities.

           (g) The indemnification and contribution required by this SECTION 6
shall be made by periodic payments of the amount thereof during the course of
the investigation or defense, as and when bills are received or expense, loss,
damage or liability is incurred.

           7. PARTICIPATION IN UNDERWRITTEN REGISTRATIONS. (a) No Person may
participate in any registration or other Public Offer hereunder which is
underwritten unless such Person (i) agrees to sell such Person's securities on
the basis provided in any underwriting arrangements approved by the Person or
Persons entitled hereunder to approve such arrangements, (ii) completes and
executes all questionnaires, powers of attorney, indemnities, underwriting
agreements and other documents required under the terms of such underwriting
arrangements, and (iii) furnishes such information regarding such Person as the
Company may reasonably request and as shall be required in connection with such
registration; PROVIDED THAT neither Carrier One nor any Management Investor
shall be required to make any representations or warranties to the Company or
the underwriters (other than representations and warranties regarding Carrier
One, or such Management Investor, and Carrier One's or such Management
Investor's intended method of distribution) or to undertake any indemnification
obligations to the Company or the underwriters with respect thereto, except as
otherwise provided in SECTION 6.


                                       15

<PAGE>

           (b) Each Person that is participating in any registration or other
Public Offer hereunder agrees that, upon receipt of any notice from the Company
of the happening of any event of the kind described in SECTION 4(e), such Person
will forthwith discontinue the disposition of its Registrable Securities
pursuant to the registration statement, or such Public Offer until such Person's
receipt of the copies of a supplemented or amended prospectus, offering circular
or memorandum or other offering document, as applicable, as contemplated by such
SECTION 4(e). In the event the Company shall give any such notice, the
applicable time period mentioned in SECTION 4(b) during which a Registration
Statement is to remain effective shall be extended by the number of days during
the period from and including date of the giving of such notice pursuant to this
Section to and including the date when Carrier One shall have received the
copies of the supplemental or amended prospectus, offering circular or
memorandum or other offering document, as applicable, contemplated by SECTION
4(e).

           8. RULE 144 REPORTING. With a view to making available the benefits
of certain rules and regulations of the Commission that may permit the sale of
Registrable Securities to the public without registration, the Company agrees at
all times after the Company has filed a registration statement with the
Commission pursuant to the requirements of either the Securities Act or the
Exchange Act to use its best efforts to: (a) make and keep public information
regarding the Company available as those terms are understood and defined in
Rule 144 under the Securities Act; (b) file with the Commission in a timely
manner all reports and other documents required of the Company under the
Securities Act and the Securities Exchange Act at any time after it has become
subject to such reporting requirements; and (c) so long as Carrier One or a
Management Investor owns any Registrable Securities, furnish to Carrier One or
such Management Investor forthwith upon written request a written statement by
the Company as to its compliance with the reporting requirements of Rule 144,
and of the Securities Act and the Exchange Act, a copy of the most recent annual
or quarterly report of the Company, and such other reports and documents so
filed as Carrier One or such Management Investor may reasonably request in
availing itself of any rule or regulation of the Commission allowing a holder to
sell any such securities without registration.

           9. DEFINITIONS.

           "BENEFICIAL INVESTORS" means industry experts or other individuals
whose affiliation with the Company should, in the good faith judgment of the
Board, provide the Company a with strategic advantage.

           "BOARD" means the Board of Directors of the Company.

           "COMMISSION" has the meaning set forth in SECTION 1(c).


                                       16

<PAGE>

           "COMPANY" means Carrierl International S.A., a Luxembourg SOCIETE
ANONYME, or any company or other entity into which Carrierl International S.A.
is converted or merged into or which becomes the direct or indirect owner of all
the Equity Securities of Carrierl International S.A.

           "DEMAND REGISTRATION" has the meaning set forth in Section 1(a).

           "DEMAND REGISTRATION CUTBACK" has the meaning set forth in
SECTION 1(d).

           "EFFECTIVE PERIOD" has the meaning set forth in Section 1(c).

           "EQUITY SECURITIES" means (i) the Shares (including, without
limitation, the Purchased Securities), (ii) any warrants, options or other
rights to subscribe for or to acquire, directly or indirectly (whether pursuant
to any division or split of Shares or other interests in the Company or in
connection with a combination, exchange, reorganization, recapitalization,
reclassification, merger, consolidation or other business combination
transaction involving the Company or otherwise), any Shares or other equity
interests in the Company, (iii) any Shares or other equity interests in the
Company or any bonds, notes, debentures or other securities convertible into or
exchangeable for, directly or indirectly (whether pursuant to a Share split or
Share division or in connection with a combination, exchange, reorganization,
recapitalization, reclassification, merger, consolidation or other business
combination transaction involving the Company or otherwise), any Shares or other
equity interests of the Company including pursuant to the transactions
contemplated by Section 4 of the Securityholders Agreement, and (iv) any
interests in any of the foregoing, including any American or Global Depositary
receipts or shares representing any of the Equity Securities referred to in
clauses (i) to (iii) above, in each case outstanding at any time.

           "IPO" means the initial underwritten public offering of any Equity
Securities within the United States.

           "LONG-FORM REGISTRATION"has the meaning set forth in Section 1(a).

           "PIGGYBACK REGISTRATION" has the meaning set forth in Section 2(a).

           "PUBLIC OFFER" means any underwritten public offering of any Equity
Securities in any jurisdiction or any underwritten private offering or series of
private offerings in one or more jurisdictions of Equity Securities in Europe
which is accompanied by a listing of the Equity Securities on a recognized
national stock exchange or introduction of the Equity Securities to trading on a
recognized national over-the-counter market in Europe.

           "QIU" has the meaning set forth in SECTION 1(f).


                                       17

<PAGE>

           "PERMITTED HOLDER" means any of the following: any of Providence
Equity Partners L.P., Providence Equity Partners 11 L.P., Providence Equity
Partners III L.P., Primus Capital Fund IV Limited Partnership and Primus
Executive Fund Limited Partnership and any of the respective Affiliates or
successors of the foregoing.

           "REGISTRABLE SECURITIES" means, at any time, (i) the Shares issued
and outstanding at such time, (ii) Shares issued upon the conversion of or
exchange of any Equity Securities, (iii) any Equity Securities issued or
issuable, directly or indirectly, with respect to the securities referred to in
clauses (i) or (ii) above by way of a dividend or split or in connection with a
combination, exchange, reorganization, recapitalization, reclassification,
merger, consolidation or other business combination transaction.

           "REQUIRED REGISTRATION" has the meaning set forth in Section 1(c).

           "SECURITIES ACT" has the meaning set forth in SECTION 1(a).

           "SECURITIES EXCHANGE ACT" has the meaning set forth in SECTION 1(c).

           "SECURITYHOLDERS AGREEMENT" means that certain Securityholders
Agreement dated as of the date hereof among the Company, Carrier One and the
Management Investors, as amended, modified or supplemented from time to time.

           "SHARES" means the ordinary shares of the Company.

           "SHORT-FORM REGISTRATION" has the meaning set forth in SECTION 1(a).

           "US PUBLIC OFFER" means any underwritten public offering of any
Equity Securities within the United States.

           "WARRANT SHARES" means ordinary shares (or other securities) issued
or issuable upon exercise of warrants pursuant to either of the Warrant
Agreements, dated as of February 19, 1999, between the Company and the Chase
Manhattan Bank,

           10. MISCELLANEOUS. (a) NO INCONSISTENT AGREEMENT. The Company shall
not hereafter enter into any agreement with respect to its Equity Securities
which is inconsistent with or violates the rights granted to Carrier One and
Management Investors in this Agreement.

           (b) ADJUSTMENTS AFFECTING REGISTRABLE SECURITIES. Except as otherwise
permitted herein, after an IPO or other Public Offer the Company shall not take
any action, or permit any change to occur, with respect to its Equity Securities
which would adversely affect the ability of Carrier One and Management Investors
to include their Registrable Securities in a registration or other Public Offer
undertaken pursuant to this


                                       18

<PAGE>

Agreement or which would materially and adversely affect the marketability of
such Registrable Securities in any such registration or other Public Offer
(including, without limitation, effecting a split or a combination of its Equity
Securities).

           (c) REMEDIES. Any Person having rights under any provision of this
Agreement shall be entitled to enforce such rights specifically to recover
damages caused by reason of any breach of any provision of this Agreement and to
exercise all other rights granted by law. The parties hereto agree and
acknowledge that money damages may not be an adequate remedy for any breach of
the provisions of this Agreement and that any party may in its sole discretion
apply to any court of law or equity of competent jurisdiction (without posting
any bond or other security) for specific performance and for other injunctive
relief in order to enforce or prevent violation of the provisions of this
Agreement.

           (d) AMENDMENTS AND WAIVERS. No modification to or amendment of any
provision of this Agreement shall be effective against the Company, Carrier One,
or any Management Investor unless such modification or amendment is approved in
writing by Carrier One and the Company and, if it materially adversely affects
the rights of the holders of the Management Shares hereunder, is approved in
writing by the holders of a majority of the Management Shares, it being
understood that no consent of the holders of the Management Shares shall be
required to add additional employees and directors of the Company and its
Affiliates as direct parties to this Agreement, but any modification to or
amendment of any provision of this Agreement executed and delivered in writing
by the holders of a majority of the Management Shares shall be binding upon all
such holders; provided that no such modification, amendment or waiver of this
Agreement which materially, adversely and disproportionately affects any one
holder of Securityholder Securities, as such, shall be effective against such
holder without the prior written consent of such holder. No waiver of the rights
and obligations hereunder of the parties hereto shall be effective unless such
waiver is in writing and duly executed and delivered by Carrier One and, if it
materially adversely affects the rights of the holders of the Management Shares
hereunder, is approved in writing by the holders of a majority of the Management
Shares, but any waiver of any rights or obligations hereunder executed and
delivered in writing by the holders of a majority of the Management Shares shall
be binding upon all such holders; provided that no such waiver of this Agreement
which materially, adversely and disproportionately affects any one holder of
Securityholder Securities, as such, shall be effective against such holder
without the prior written consent of such holder. The failure of any party
hereto to enforce any of the provisions of this Agreement shall in no way be
construed as a waiver of such provisions and shall not affect the right of such
party thereafter to enforce each and every provision of this Agreement in
accordance with its terms.

           (e) SUCCESSORS AND ASSIGNS. All covenants and agreements in this
Agreement by or on behalf of any of the parties hereto shall bind and inure to
the benefit of the


                                       19

<PAGE>

respective successors and assigns of the parties hereto, including any member of
Carrier One and such member's assigns, whether so expressed or not. In addition,
whether or not any express assignment has been made, the provisions of this
Agreement which are for the benefit of the purchasers or holders of any type of
Registrable Securities are also for the benefit of, and enforceable by, any
subsequent holder of Registrable Securities. Notwithstanding the foregoing, in
order to obtain the benefit of this Agreement, any subsequent holder of
Registrable Securities must execute a counterpart to this Agreement, thereby
agreeing to be bound by the terms hereof.

           (f) SEVERABILITY. Whenever possible, each provision of this Agreement
shall be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Agreement is held to be prohibited
by or invalid under applicable law, such provision shall be ineffective only to
the extent of such prohibition or invalidity, without invalidating the remainder
of this Agreement.

           (g) COUNTERPARTS. This Agreement may be executed simultaneously in
two or more counterparts, any one of which need not contain the signatures of
more than one party, but all such counterparts taken together shall constitute
one and the same Agreement.

           (h) DESCRIPTIVE HEADINGS. The descriptive headings of this Agreement
are inserted for convenience only and do not constitute a part of this
Agreement. The words "hereof", "herein" and "hereunder" and words of similar
import when used in this Agreement shall refer to this Agreement as a whole and
not to any particular provision of this Agreement. Unless otherwise specified
herein, the term "or" has the inclusive meaning represented by the term "and/or"
and the term "including" is not limiting. All references as to "Sections",
"Subsections", "Articles", "Schedules" and "Exhibits" shall be to Section,
Subsections, Articles, Schedules and Exhibits, respectively, of this Agreement
unless otherwise specifically provided.

           (i) GOVERNING LAW. The corporate law of the State of New York shall
govern all issues and questions concerning the relative rights of the Company,
Carrier One and the Management Investors. All other issues and questions
concerning the construction, validity, interpretation and enforcement of this
Agreement and the exhibits and schedules hereto shall be governed by, and
construed in accordance with, the laws of the State of New York, without giving
effect to any choice of law or conflict of law rules or provisions (whether of
the State of New York of any other jurisdiction) that would cause the
application of the laws of any jurisdiction other than the State of New York. In
furtherance of the foregoing, the internal law of the State of New York shall
control the interpretation and construction of this Agreement (and all schedules
and exhibits hereto), even though under the jurisdiction's choice of law or
conflict of law analysis, the substantive law of some other jurisdiction would
ordinarily apply.


                                       20

<PAGE>

           (j) SUBMISSION TO JURISDICTION.

           The courts of England have jurisdiction to hear and decide any suit,
action or proceedings, and to settle any disputes, which may arise out of or in
connection with this Agreement (respectively, "PROCEEDINGS" and "DISPUTES") and
for this purpose each party irrevocably submits to the jurisdiction of the
Courts of England.

           Paragraph (b) above does not prevent any party to this Agreement from
taking proceedings relating to Proceedings or Disputes in any other courts with
jurisdiction.

           Each party irrevocably waives any objection which it might at any
time have to the courts of England being nominated as the forum to hear and
decide any Proceedings and to settle any disputes and agrees not to claim that
the courts of England are not a convenient or appropriate forum.

           (k) NOTICES. Any notices or other communications required to be given
pursuant to this Agreement shall be in writing and shall be deemed given: (i)
upon delivery, if by hand; (ii) three (3) Business Days after mailing, if sent
by registered or certified mail, postage prepaid, return receipt requested;
(iii) one (1) Business Day after mailing, if sent via overnight courier; or (iv)
upon transmission, if sent by telex or facsimile except that if such notice or
other communication is received by telex or facsimile after 5:00 p.m. on a
Business Day at the place of receipt, it shall be effective as of the following
Business Day. All notices and other communications hereunder shall be given as
follows:

           (a)  If to the Company, to it at:

                c/o Carrierl International GmbH
                Militarstrasse 36
                CH-8004 Zurich
                Attention:
                Facsimile: 01/ 297 26 01
                Telephone: 01/ 297 26 00

                with a copy to:
                Providence Equity Partners, Inc.
                901 Fleet Center
                50 Kennedy Plaza
                Providence, RI 02903
                Attn: Glenn M. Creamer
                Facsimile: 401-751-1790
                Telephone: 401-751-1700


                                       21

<PAGE>

                and a copy to:

                Edwards & Angell
                2900 Bank Boston Tower
                Providence, Rhode Island 02903
                Attention: David K. Duffell, Esq.
                Facsimile: 401-276-6611
                Telephone: 401-274-9200

           (b)  If to a Management Investor, to it at his address set forth in
the Securities Purchase Agreement.

           Any party may change its address for receiving notice by written
notice given to the other names above in the manner provided above.


                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]


                                       22

<PAGE>

           IN WITNESS WHEREOF, the parties hereto have executed this Agreement
on the day and year first above written.

                                             CARRIER ONE, LLC


                                             By: /s/ Glen M. Creamer
                                                --------------------------------
                                             Name:  Glen M. Creamer
                                             Title: Chairman


                                             CARRIER ONE INTERNATIONAL S.A.


                                             By: /s/ Glen M. Creamer
                                                --------------------------------
                                             Name:
                                             Title:


     [Signature page to Amended and Restated Registration Rights Agreement]


                                       23

<PAGE>


                             /s/ Stig Johansson
                                 Stig Johansson


                              /s/ Joachim Bauer
                                  Joachim Bauer


                             /s/ Eugene A. Rizzo
                                 Eugene A. Rizzo


                             /s/ Kees Van Ophem
                                 Kees Van Ophem


                               /s/ Neil Craven
                                   Neil Craven


                              /s/ Terje Nordahl
                                  Terje Nordahl


                              /s/ Edward Gross
                                  Edward Gross


                             /s/ Philip Poulter
                                 Philip Poulter




     [Signature page to Amended and Restated Registration Rights Agreement]


                                       24

<PAGE>

                                                                   Exhibit 10.14


                       SECURITYHOLDERS' AGREEMENT


        THIS SECURITYHOLDERS' AGREEMENT is made as of March 1, 1999, between
Carrier1 International S.A., a Luxembourg SOCIETE ANONYME (the "Company"),
Carrier One, LLC, a Delaware limited liability company ("Carrier One"), and each
of the other securityholders from time to time a party hereto (together with
Carrier One, the "Securityholders"). Capitalized terms used but not otherwise
defined herein are defined in SECTION 10 hereof or in the Securities Purchase
Agreement referred to below.

        The Company and the Securityholders desire to enter into this Agreement
for the purposes, among others, of (i) assuring continuity of the management and
ownership of the Company and (ii) limiting the manner and terms of which
Securityholder Securities may be transferred. The execution and delivery of this
Agreement is a condition to certain Securityholders' purchase of certain
Purchased Securities, as defined in, and pursuant to, the Securities Purchase
Agreement (as amended from time to time, the "Securities Purchase Agreement"),
dated as of March 1, 1999, among the Company, Carrier One and each of the
Purchasers (as defined therein).

        NOW THEREFORE, in consideration of the mutual covenants contained herein
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, the parties to this Agreement, intending to be legally
bound, hereby agree as follows:

        Section 1. RESTRICTIONS ON TRANSFER OF MANAGEMENT SECURITIES. (a) IN
GENERAL. No Management Holder shall sell, transfer, assign, pledge or otherwise
dispose of (whether with or without consideration and whether voluntarily or
involuntarily or by operation of law) any direct or indirect interest in (a
"Transfer") such Management Holder's Management Securities without the prior
written consent of the Board, except pursuant to or as is permitted by (i)
SECTIONS 4 AND 7 hereof, and (ii) a pledge of Management Securities in favor of
the Company to secure obligations owing to the Company; PROVIDED in each case
that the applicable requirements of SECTIONS 1(c), 2, and 3 (if any) are also
satisfied; and PROVIDED FURTHER that invested Management Securities (including,
without limitation, options which have not yet become exercisable) may not be
transferred in any event. Notwithstanding obtaining the required approval of the
Board, all Transfers of Management Securities for which Board approval is
required shall be subject to compliance with the provisions of SECTION 1(b)
hereof.

        (b) RIGHT OF FIRST REFUSAL. If one or more Management Holders desires to
Transfer (the Securityholder(s) proposing the Transfer being referred to in


<PAGE>

this SECTION 1(b) as the "Transferring Securityholders") all or a portion of
his Management Securities the Transferring Securityholders shall first comply
with the following terms and conditions:

        (i) The Transferring Securityholders shall first deliver to Carrier One
or its transferee who becomes a party to this Agreement from time to time
(collectively referred to in this SECTION 1(b) as the "Offerees" and each as an
"Offeree") a written notice (the "Notice of Proposed Transfer") specifying the
name and address of the proposed transferee of the Management Securities
(hereinafter sometimes referred to as the "Proposed Purchaser"), the type and
total number of such Management Securities which the Transferring
Securityholders then desire to transfer to said Proposed Purchaser (the "Offered
Securities"), all of the terms, including the purchase price (which shall be
payable only in cash), upon which the Transferring Securityholders propose to
transfer the Offered Securities to the Proposed Purchaser, and stating that the
Offerees shall have the right to purchase the Offered Securities at the price
and in accordance with the terms and provisions specified in such Notice of a
Proposed Transfer.

        (ii) The Offerees shall have the option, for the thirty (30) consecutive
day period commencing on the date the Offerees receive the Notice of Proposed
Transfer, to purchase all of the Offered Securities at the price and terms
specified in the Notice of Proposed Transfer. The Offerees must give written
notice of their election to the Offeror during such 30-day period.

        (iii) Each Offeree shall have the right (but not the obligation) to
purchase that number of the Offered Securities as shall be equal to the number
of Offered Securities multiplied by a fraction, the numerator of which shall be
the number of Securityholder Securities then owned by such Offeree and the
denominator of which shall be the aggregate number of Securityholder Securities
then owned by all of the Offerees. The amount of such Offered Securities that
each Offeree is entitled to purchase under this SECTION 1(b) shall be referred
to as its "Pro Rata Fraction."

        (iv) The Offerees shall have a right of oversubscription such that if
any Offeree fails to elect to purchase its full Pro Rata Fraction of the Offered
Securities, the remaining Offerees shall have the right to purchase up to the
balance of such remaining Offered Securities not so purchased. The Offerees may
exercise such right of oversubscription by electing to purchase more than their
Pro Rata Fraction of the Offered Securities, but such election must be made in
the initial election notice given pursuant to clause (ii) above. If, as a result
thereof, such oversubscriptions


                                       2
<PAGE>

exceed the total number of the Offered Securities available in respect to
such oversubscription privilege, the oversubscribing Offerees shall be cut
back with respect to oversubscriptions on a pro rata basis in accordance with
their respective Pro Rata Fractions or as they may otherwise agree among
themselves.

        (v) If the Offerees have not elected to purchase all of the Offered
Securities, then the Transferring Securityholder shall have the right, until the
expiration of ninety (90) consecutive days commencing on the first day
immediately following the expiration of the 30-day period specified in paragraph
(ii) above, to Transfer the Offered Securities to the Proposed Purchaser at the
price and terms specified in the Notice of Proposed Transfer. If for any reason
the Offered Securities are not Transferred to the Proposed Purchaser within such
period and at such stated price and on such stated terms, the right to Transfer
in accordance with the Notice of Proposed Transfer shall expire and the
provisions of this Agreement shall continue to be applicable to the Offered
Securities but the Transferring Securityholder shall have the right, at any time
thereafter and subject to again deliver a new Notice of Proposed Transfer
complying with this SECTION 1(b).

        (vi) The purchase price for the Offered Securities to be paid by the
Offerees or the Proposed Purchaser shall be the price set forth in the Notice of
Proposed Transfer.

        (vii) The Offerees purchasing the greatest percentage of the Offered
Securities shall set the place, time and date for the closing of the purchase of
the Offered Securities, which closing shall not be more than 20 days after the
first day immediately following the expiration of the 30-day period specified in
paragraph (ii) above; provided, however, such date for closing shall be extended
as reasonably necessary for the Company, the Offerees and the Transferring
Securityholders, as the case may be, to obtain the consent, approval or other
authorization of any Governmental Entity required for such Transfer. The
purchase price of the Offered Securities shall, unless otherwise agreed in
writing by the parties to such transaction, be paid in cash, by certified check
or wire transfer of funds at the date of the closing. At the closing, the
Offerees shall deliver the consideration required by clause (vi) above, and the
Transferring Securityholder shall deliver an assignment of the Offered
Securities and other instruments reasonably satisfactory to the Offerees and
their counsel.

        (c) INDIRECT TRANSFERS. No Management Holder that is not an individual
(a "Restricted Holder") shall permit the issuance of additional interests in


                                       3
<PAGE>

such Restricted Holder or any Transfer of any interest of any Indirect Owner in
such holder.

        (d) MARKET STANDOFF. To the extent not inconsistent with applicable
law, no Management Holder shall effect any sale or distribution (including
sales pursuant to Regulation S or Rule 144 under the Securities Act) of
Management Securities, or any securities, options or rights convertible into
or exchangeable or exercisable for such securities, during the 10 day period
prior to and the 180 day period after the date of the closing of a sale
pursuant to an effective registration statement under the Securities Act of
1933, as amended, or the date of the closing of a public offering or private
offering accompanied by listing of any Securityholder Securities within or
outside of the United States, of Securityholder Securities, whether for the
account of the Company or Carrier One or its transferees, unless (in any such
case) the underwriter managing the registered public offering or the Board
agrees in writing otherwise.

        (e) TERMINATION OF RESTRICTIONS. The restrictions set forth in
paragraphs (a), (b) and (c) of this SECTION 1 shall continue with respect to
each Management Security until (i) the Company's Securityholder Securities are
listed on the Luxembourg, New York, London or American Stock Exchange or are
quoted on the NASDAQ National Market System or SEAQ or EASDAQ, or listed or
quoted on other European national stock exchanges or, at the initiative of the
Company, over-the-counter market of any jurisdiction, (ii) Trading Volume equals
or exceeds the number of Securityholder Securities then held by Carrier One and
its transferees, (iii) the Securityholder Securities have an average closing
price per share for the prior eight week period exceeding 250% of Carrier One's
cost per Securityholder Security and (iv) the Securityholder Securities held by
Carrier One and its transferees are not subject to lock-up or escrow provisions
and are freely tradable (the "Active Market Event").

        Section 2. ADDITIONAL RESTRICTIONS ON TRANSFER. (a) RESTRICTED
SECURITIES. The Securityholder Securities have not been registered under the
Securities Act nor under any other applicable securities laws and regulations in
any jurisdiction and, therefore, in addition to the other restrictions on
Transfer contained in this Agreement, cannot be sold unless subsequently
registered under the Securities Act or an exemption from such registration is
then available and may only be sold outside of the United States subject to
compliance with any applicable securities laws and regulations. Pursuant to the
Articles, any transfer of the Securityholder Securities requires the approval of
the Board.


                                       4
<PAGE>

        (b) OPINION OF COUNSEL. No Securityholder may Transfer any
Securityholder Securities (except pursuant a Public Sale or, in the case of
Carrier One and its transferees, to an Affiliate or such Affiliates' Affiliate,
or pursuant to SECTION 1(a)(i) and (ii)) without first delivering to the Company
(unless waived by the Board) an opinion of counsel (reasonably acceptable in
form and substance to the Board) that no registration, qualification or other
approval under the Securities Act or any other applicable securities laws and
regulations of jurisdictions outside of the United States, is required in
connection with such Transfer.

        Section 3. TRANSFER. Prior to Transferring any Management Securities
(other than pursuant to SECTIONS 4 and 7 or pursuant to a Public Sale), the
Transferring Management Holder shall cause the prospective Transferee to be
bound by this Agreement, and any other agreements executed by all or
substantially all of the Management Holders (collectively, the "Other
Agreements"). Any Transfer or attempted Transfer of any Management Securities
in violation of any provisions of this Agreement shall be void, and the
Company shall not record such Transfer on its books or treat any purported
Transferee of such Management Securities as the owner of such securities for
any purpose.

        Section 4. SALE OF THE COMPANY; PLEDGE TO SECURE FINANCING. (a) In the
event the Board approves a Sale of the Company, each Securityholder shall
promptly take all necessary or desirable action within such Person's control
(including, without limitation, the removal and election of directors,
attendance at members' and shareholders' meetings in person or by proxy for the
purposes of obtaining a quorum and the execution of written consents in lieu of
meetings) such that any proposal, resolution or other matter relating to the
implementation of such Sale of the Company shall be implemented and if the
Securityholders are entitled to vote on any such matter, whether by law, under
the Articles or otherwise, all of the Securityholder Securities and any other
securities of the Company over which such Securityholder has control shall (if
permitted to vote) be voted in favor of such Sale of the Company.

        (b) Each Securityholder will consent to and raise no objections against
a Sale of the Company approved by the Board. If at any such Sale of the Company
structured as a sale of securities, or in the event of any Sale of the LLC, then
Carrier One may, at its sole discretion, elect to purchase or have its
Affiliates or other designee or designees (which may include the Company)
purchase the Management Securities. In such event, each Management Holder shall
sell the Securityholder Securities and any other securities of the Company held
by him or it to Carrier One or its designee on the terms and conditions approved
by the Board. Each Securityholder


                                       5
<PAGE>

shall promptly take all action necessary and
desirable in connection with the consummation of a Sale of the Company or a Sale
of the LLC, including, without limitation, the waiver of all appraisal rights
available to any such Securityholder under applicable law. Each Securityholder
will bear his or its pro rata share (based upon the number of Securityholder
Securities held by him or it on a fully diluted basis) of the cost of any sale
of equity securities pursuant to such a Sale of the Company or the Sale of the
LLC to the extent such costs are incurred for the benefit of all Securityholders
and are not otherwise paid by the Company or the acquiring party. Costs incurred
by Securityholders on their own behalf will not be considered costs of the
transaction hereunder.

        (c) In the event the Board requests that the Securityholders pledge
their Securityholder Securities to secure financing to be provided to the
Company and/or one or more of its Subsidiaries ("Company Financing"), each
Securityholder shall promptly take all necessary or desirable action with
such Person's control, including executing any and all documents requested by
the Board, to pledge the Securityholder Securities held by him or it to
secure such Company Financing; provided, however, the terms of the Company
Financing shall not require that a Securityholder be personally liable for
such Financing and recourse against any Securityholder for such Company
Financing (absent the consent of such Securityholder) shall be limited to the
Securityholder Securities pledged to secure the Company Financing and the
terms and conditions of the pledge to be made by each Securityholder shall be
substantially the same.

        Section 5. BOARD COMPOSITION. (a) From and after the date hereof, and
until the provisions of this SECTION 5 cease to be effective, each
Securityholder shall vote all of its Securityholder Securities and any other
voting securities of the Company over which such Securityholder has voting
control and shall take all other necessary or desirable actions within its
control (whether in its capacity as a Securityholder, stockholder, director,
member of a board committee or officer of the Company, or otherwise, and
including, without limitation, attendance at meetings in person or by proxy for
purposes of obtaining a quorum and execution of written consents in lieu of
meetings), and the Company shall take all necessary or desirable actions within
its control (including, without limitation, calling special Board and
Securityholder meetings), so that for so long as Stig Johansson is employed by
the Company or a Subsidiary, Stig Johansson shall be elected to the Board. It is
further agreed that each of Joachim Bauer, Eugene A. Rizzo, Kees Van Ophem and
Neil Craven shall have the right to notice of, and the right to attend and
participate in (but not vote at) the meetings of the Board for so long as he is
employed by the Company or a Subsidiary.


                                       6
<PAGE>

        (b) The Company shall pay the reasonable out-of-pocket expenses incurred
by each director and observer in connection with attending (i) the meetings of
the Board, any Sub Board and any committees thereof and (ii) any other meetings
at the request of any Company or any of its Subsidiaries. So long as any
director designated pursuant to SECTION 5 serves on the Board or any Sub Board,
and for six years thereafter, the constituent documents of the Company and each
of its Subsidiaries, as appropriate, shall provide for indemnification and
exculpation of directors to the fullest extent permitted under applicable law.

        (c) No director, officer, employee or Securityholder of the Company, nor
any such Person's spouse, sibling, parent, child or any spouse thereof (each, a
"Family Member"), or any corporation, partnership, trust or other entity in
which such Person, or any Family Member of such Person, is the holder of a
majority of the outstanding capital stock thereof, shall enter into any
transaction, with the Company or its Subsidiaries, including any contract,
agreement or other arrangement, unless

(i) the material facts as to such Person's interest and as to the contract or
transaction are disclosed or are known to the Board or any committee thereof and
the Board or such committee in good faith authorizes the contract or transaction
by the affirmative vote of a majority of the disinterested directors; or

(ii) the contract or transaction is fair to the Company or its Subsidiary, as
the case may be, as of the time it is authorized, approved or ratified by the
Board, any committee thereof or the Securityholders.

        (d) The provisions of this SECTION 5 shall terminate upon the initial
Public Sale of Securityholder Securities.

        Section 6. PREEMPTIVE RIGHTS. (a) Except for (i) issuances of Shares to
the employees of the Company and its Subsidiaries pursuant to the Option
Agreements and pursuant to any other plan or arrangement approved by the Board,
(ii) issuances of Shares pursuant to a Public Sale, (iii) the issuance of Shares
to Carrier One pursuant to the Securities Purchase Agreement, if the Company
authorizes the issuance or sale of any Shares or any securities including any
options, warrants or rights to acquire any Shares, and (iv) issuances of Shares
to the holders of Warrants under the Euro Warrant Agreement and Dollar Warrant
Agreement entered into between Carrier1 International S.A. and Chase Manhattan
Bank, respectively signed on or about February 19, 1999, the Company shall first
by written notice offer


                                       7
<PAGE>

to sell to Carrier One a portion of such Securityholder Securities or other
securities equal to the quotient determined by dividing (1) the number of
Securityholder Securities held Carrier One by (2) the total number of
outstanding Securityholder Securities. Carrier One or its designees shall be
entitled to purchase such securities at the most favorable price and on the
most favorable terms as such securities are to be offered to any other Person.

        (b) In order to exercise its purchase rights hereunder, Carrier One or
its designees must within 30 days after receipt of written notice from the
Company describing in reasonable detail the securities being offered, the
purchase price thereof, the payment terms and its percentage allotment, deliver
a written notice to the Company describing its election hereunder.

        (c) Upon expiration of the offering period described above, the Company
shall be entitled to sell such securities which Carrier One or its designees has
not elected to purchase during the 90 days following such expiration on terms
and conditions no more favorable to the purchasers thereof than those offered to
Carrier One. Any securities offered or sold by the Company after such 90-day
period must be reoffered to Carrier One pursuant to the terms of this SECTION 6.

        (d) Each of the parties to this Agreement agrees to vote its Shares and
to waive its pre-emptive rights under the Articles of the Company, if required,
so as to give effect to the rights of Carrier One under this SECTION 6,
including the right to designate purchasers of Shares. The right of Carrier One
under this SECTION 6 shall terminate upon the consummation of the initial Public
Sale by the Company.

        (e) In the event that the holders of a majority of the Shares of the
Company proposes the issuance of Shares by the Company in a Public Sale, each of
the parties to this Agreement shall vote its Shares in favor of such Public Sale
and related capital increase and amendment to the Articles and shall waive any
pre-emptive rights which it may have in respect of such sale and increase.

        Section 7. CONFIDENTIALITY, NONCOMPETITION AND NONSOLICITATION
COVENANTS. (a) Each Management Holder acknowledges that in the course of
providing services to the Company and its Subsidiaries, such Management Holder
will become familiar with the trade secrets, Confidential Information and other
intellectual property concerning Carrier One, the Company and its Subsidiaries.
No Management Holder shall, in any manner, whether directly or indirectly, use
for his own benefit or the benefit of any other Person, nor disclose, divulge,
render or offer, any Confidential Information, except on behalf of Carrier One,
the Company or its


                                       8
<PAGE>

Subsidiaries in the course of the proper performance of his duties under any
employment agreement between such Management Holder and Carrier One, the
Company or any of its Subsidiaries. Each Management Holder acknowledges and
agrees that any and all such Confidential Information will be received and
held by him in a confidential capacity.

        (b) Each Management Holder acknowledges that in the course of
providing services to Carrier One, the Company and its Subsidiaries, (i) the
services of the Management Holder shall be of special, unique and
extraordinary value to Carrier One, the Company and its Subsidiaries and (ii)
Carrier One, the Company and the Subsidiaries' ability to accomplish their
purposes and to successfully compete in the marketplace depend substantially
on the skills and expertise of the Management Holder. Each Management Holder
acknowledges and agrees that, given the interconnected nature of the
international telecommunications network businesses of Carrier One, the
Company and its Subsidiaries, Carrier One, the Company and its Subsidiaries
would be irreparably damaged if such Management Holder were to not devote
substantially all of his business time and efforts to the business and
affairs of Carrier One, the Company and its Subsidiaries during the term of
any employment contract with Carrier One, the Company or any of its
Subsidiaries or were to provide directly or indirectly similar services to
any person competing with Carrier One, the Company or any of its Subsidiaries
or were to engage in a similar a business other than as specifically
permitted by this SECTION 7. Accordingly, in further consideration of the
compensation to be paid by Carrier One, the Company or its Subsidiaries to
such Management Holder, the issuance of options to purchase equity in the
Company, and to induce Carrier One to enter into the Securities Purchase
Agreement, each Management Holder agrees, from and after the date hereof and
during the applicable Non-Compete Period, that he will not, singly, jointly,
or as an employee, agent or partner of any partnership or as an officer,
agent, employee, director, stockholder (except of not more than two percent
(2%) of the outstanding stock of any company listed on a national securities
exchange or actively traded in the over the counter market) or investor in
any other corporation or entity, or as a consultant, advisor, or independent
contractor to any such partnership, corporation or entity, or in any other
capacity, directly, indirectly or beneficially, in any jurisdiction in which
Carrier One, the Company or its Subsidiaries is operating:

(i) own, manage, operate, join, control, or participate in the ownership,
management, operation, or control of, or work for (as an employee, agent,
consultant, advisor or independent contractor), or permit the use of his name
by, or provide financial or other assistance to, or be connected in any
manner with, any person, partnership, corporation, or entity which is in the


                                       9
<PAGE>

international long distance telecommunications business or which otherwise is
in direct or indirect competition with any business conducted by Carrier One,
the Company or any of the Subsidiaries on the date hereof or at any time
during the applicable Non-Compete Period;

(ii) induce or attempt to induce any person who, on the date hereof or at any
time during the applicable Non-Compete Period, is an employee of Carrier One,
the Company or any of the Subsidiaries, to terminate his or her employment
with such company; or

(iii) induce or attempt to induce any person, business, or entity which is a
supplier, distributor, or customer of Carrier One, the Company or any of the
Subsidiaries or which otherwise is a contracting party with Carrier One, the
Company or any of the Subsidiaries, as of the date hereof or at any time
during the applicable Non-Compete Period, to terminate or modify any written
or oral agreement or understanding with Carrier One, the Company or any of
the Subsidiaries.

Each Management Holder acknowledges and agrees that the limitations set forth
in this SECTION 7 are reasonable with respect to scope, duration and area and
are properly required for the protection of the legitimate business interests
of Carrier One, the Company and its Subsidiaries. Each Management Holder
agrees that the covenants set forth in this SECTION 7 shall be enforced to
the fullest extent permitted by law. Accordingly, if in any judicial or
similar proceeding a court or any similar judicial body shall determine that
such covenant is unenforceable because it covers too extensive a geographical
area or survives too long a period of time, or for any other reason, then the
parties intend that such covenant shall be deemed to cover only such maximum
geographical area and maximum period of time and shall otherwise be deemed to
be limited in such manner as will permit enforceability by such court or
similar body. In the event of a breach or violation by any Management Holder
of this SECTION 7, the Non-Compete Period with respect to such Management
Holder shall be extended for the number of days in the period from the date
of such breach or violation through and including the date that such breach
or violation has been fully cured or ceases.

        (c) SPECIFIC PERFORMANCE. Each Management Holder agrees that his
breach of the provisions of SECTION 7(a) or (b) above will cause irreparable
damage to Carrier One and the Company and that the recovery by Carrier One
and the Company of money damages will not constitute an adequate remedy for
such breach. Accordingly, each Management Holder agrees that the provisions
of SECTIONS 7(a)


                                       10
<PAGE>

and (b) above may be specifically enforced against such Management Holder in
addition to any other rights or remedies available to Carrier One and the
Company and its Subsidiaries on account of any such breach, and each
Management Holder expressly waives the defense in any equitable proceeding
that there is an adequate remedy at law for any such breach. Each Management
Holder agrees that if the provisions of SECTIONS 7(a) and (b) for any reason
cannot be specifically enforced against such Management Holder for the entire
Non-Compete Period which is applicable, then Management Holder agrees that
Carrier One and the Company will be entitled to recover an amount for each
breach of the provisions of SECTIONS 7(a) and (b) equivalent to 30% of his
annual base salary earned with Carrier One, the Company or any of its
Subsidiaries or in his new position, whichever is higher; PROVIDED, HOWEVER,
that (i) payment of such amount shall not relieve such Management Holder from
observing the prohibitions contained in SECTIONS 7(a) and (b) and (ii) the
Company is entitled to be indemnified in full for damages.

        Section 8. RIGHT OF CO-SALE

        8.1 CO-SALE RIGHT. In the event that a Securityholder or Securityholders
(collectively, the "Transferor") proposes to, directly or indirectly, Transfer
(in a single transaction or a series of related transactions) Securityholder
Securities representing 50% or more of the outstanding Securityholder Securities
then held by all Securityholders (the "Transferor Securities") to any Person for
value (the "Transferee"), the remaining Securityholders (the "Remaining
Securityholders") shall have a right of co-sale (the "Right of Co-Sale") to sell
their pro rata share of the number of Securityholder Securities represented by
the Transferor Securities (the "Right of Co-Sale Pro Rata Share") on the same
terms and at the same time as the Transferor, all as described in this SECTION
8.

        8.2 RIGHT OF CO-SALE PRO RATA SHARE. The Right of Co-Sale Pro Rata Share
for each Remaining Securityholder shall be that proportion which the number of
Securityholder Securities held by such Securityholder bears to the aggregate
number of Securityholder Securities held by all Securityholders. Each Remaining
Securityholder shall have the right to sell that number of Securityholder
Securities held by such Securityholder to the Transferee (or, upon the
unwillingness of any Transferee to purchase directly from such Securityholder,
to the Transferor simultaneously with the closing of the sale by the Transferor
to the Transferee) up to its respective Right of Co-Sale Pro Rata Share
determined as of the date the Transfer Notice (as defined below) is delivered to
the such Securityholder, upon the terms and subject to the conditions pursuant
to which the Transferor sells its Transferor Securities to the Transferee.


                                       11
<PAGE>

        8.3 MECHANICS OF SALE. (a) EXERCISE BY THE SECURITYHOLDER. If the
Transferor proposes to Transfer any Transferor Securities in a transaction
subject to this SECTION 8, then it shall promptly notify, or cause to be
notified, the Remaining Securityholders, in writing, of each such proposed
Transfer (the "Transfer Notice").

Such Transfer Notice shall set forth: (i) the name of the Transferee and the
number of Securityholder Securities proposed to be Transferred, and (ii) the
proposed amount and form of consideration and terms and conditions of payment
offered by the Transferee (the "Transferee Terms"). The Right of Co-Sale may be
exercised by the Remaining Securityholders delivering a written notice to the
Transferor (the "Co-Sale Notice") within fifteen (15) calendar days following
receipt of the Transfer Notice. The Co-Sale Notice shall state the number of
Securityholder Securities that such Remaining Securityholder wishes to include
in such Transfer to the Transferee, which number may not exceed its Right of
Co-Sale Pro Rata Share. Upon the giving of a Co-Sale Notice, a Securityholder
shall be irrevocably obligated to sell the number of Securityholder Securities
set forth in its Co-Sale Notice to the Transferee on the Transferee Terms.

        (b) ASSIGNMENT OF INTEREST. If a Securityholder exercises its Co-Sale
Rights, then the Transferor shall assign to such Securityholder as much of its
interest in the agreement of sale with the Transferee as such Securityholder
shall be entitled to, and such Securityholder shall be obligated to provide the
same representations, warranties and covenants to the Transferee as the
Transferor under such agreement of sale. To the extent that any Transferee
prohibits such assignment or otherwise refuses to purchase Securityholder
Securities from a Securityholder exercising its Right of Co-Sale hereunder, then
the Transferor shall not sell to such Transferee any Transferor Securities
unless and until, simultaneously with such sale, the Transferor shall purchase
such Securityholder Securities from such Securityholder for the same
consideration per unit or share and on the same terms and subject to the same
conditions as the proposed Transfer described in the Transfer Notice.

        (c) FAILURE TO EXERCISE RIGHT OF CO-SALE; ADDITIONAL TRANSFERS. If no
Securityholder elects to exercise its Right of Co-Sale, then the Transferor may
not later than 120 days following delivery to the Remaining Securityholders of
the Transfer Notice conclude a Transfer of not less than all of the Transferor
Securities covered by the Transfer Notice on such terms and subject to
conditions not more favorable to the Transferor than those described in the
Transfer Notice. Any proposed Transfer of more Securityholder Securities by the
Transferor shall again be subject to the Right of Co-Sale and shall require
compliance by the Transferor with the procedures described in this SECTION 8.


                                       12
<PAGE>

        8.4 EXCEPTIONS TO RIGHT OF CO-SALE. The Right of Co-Sale shall not apply
to Transfers to Affiliates of a Securityholder or to an Indirect Owner of
Carrier One. The provisions of this SECTION 8 shall terminate upon an initial
public offering of Securityholder Securities.

        8.5 (a) CERTAIN RIGHTS OF CO-SALE IN RELATION TO CARRIER ONE. In the
event that Carrier One owns a majority of the outstanding shares of the
Company and a holder or holders of LLC Securities (collectively, the "LLC
Transferor") proposes to, directly or indirectly, transfer (in a single
transaction or a series of related transactions) LLC Securities (the "LLC
Transfer Securities") representing 50% or more of the outstanding LLC
Securities then held by all holders of LLC Securities to any Person for
value, the Management Holders shall have a right (the "LLC Right of Co-Sale")
to sell, and to cause Carrier One (or its designee) to purchase, at the
Adjusted Per Share Price (as defined below) a number of Management Securities
which bears the same proportion to all outstanding Management Securities that
the number of LLC Transfer Securities bears to all LLC Securities multiplied
by the fraction of the Company's outstanding shares that are owned by Carrier
One (the "LLC Right of Co-Sale Pro Rata Share") at the same time as the sale
of LLC Transfer Securities by the LLC Transferor, all as described in this
SECTION 8.5.

        (b) MECHANICS OF LLC SALE; EXERCISE BY THE SECURITYHOLDER. If the LLC
Transferor proposes to Transfer any LLC Transferor Securities in a transaction
subject to this SECTION 8.5, then Carrier One shall promptly notify, or cause to
be notified, the Management Holders in writing of such proposed Transfer (the
"LLC Transfer Notice"). The LLC Transfer Notice shall set forth: (i) the number
of LLC Securities proposed to be Transferred and the number of outstanding LLC
Securities, (ii) the proposed amount of consideration per LLC Security (the "LLC
Per Share Price") and terms and conditions of payment received by the LLC
Transferor, and (iii) the proposed Adjusted Per Share Price. The LLC Right of
Co-Sale may be exercised by the Management Holders delivering a written notice
to Carrier One (the "LLC Co-Sale Notice") within fifteen (15) calendar days
following receipt of the LLC Transfer Notice. The LLC Co-Sale Notice shall state
the number of Securityholder Securities that such Management Holder wishes to
include in such Transfer to Carrier One (or its designee), which number may not
exceed its LLC Right of Co-Sale Pro Rata Share. Upon the giving of a LLC Co-Sale
Notice, a Management Holder shall be irrevocably obligated to sell, and Carrier
One shall be irrevocably obligated to purchase, or cause the purchase of, the
number of Management Securities set forth in its LLC Co-Sale Notice to Carrier
One at the Adjusted Per Share Price.


                                       13
<PAGE>

        (c) ADJUSTED PER SHARE PRICE. For the purposes of this SECTION 8.5, the
"Adjusted Per Share Price" shall be the value of each Securityholder Security
determined on the basis of the LLC Per Share Price (after adjustment to take
into account the differences between the total share capital of Carrier One and
the total share capital of the Company, the cash value of any non-cash portion
of the LLC Per Share Price, the total number of Securityholder Securities held
by Carrier One, the total outstanding number of LLC Securities, any assets or
liabilities of Carrier One other than Securityholder Securities, and any other
matters which Carrier One determines in good faith is relevant to such
calculation), as determined in good faith by Carrier One.

        (d) EXCEPTIONS TO RIGHT OF CO-SALE. The LLC Right of Co-Sale shall
not apply to Transfers to Affiliates of a Securityholder, Transfers between
Institutional Investors or to partners of an Institutional Investor. The
provisions of this SECTION 8.5 shall terminate upon any initial public
offering or listing of Securityholder Securities.

        Section 9. UBTI. Notwithstanding anything to the contrary expressed or
implied in this Agreement, the Company shall use its best efforts to ensure that
the Company does not engage in any transactions which will cause any member of
Carrier One (or any partner or member of any such member) which is exempt from
income taxation under Section 501(a) of the United States International Revenue
Code of 1986, as amended (the "Code"), to recognize unrelated business taxable
income as defined in Sections 512 and 514 of the Code as a result of its
investment in the Company; provided, that with respect to any action taken or
omitted to be taken by the Company's management without the express written
authorization of the Board such best efforts obligation of the Company shall be
deemed satisfied by the delivery to the Company's management of an advice
memorandum in a form prepared or approved by Primus Capital Fund IV Limited
Partnership and Primus Executive Fund Limited Partnership.


        Section 10. CERTAIN DEFINITIONS.

        "AFFILIATE" shall mean, with respect to any Person (the "First Person"),
any other Person directly or indirectly controlling, controlled by or under
direct or indirect common control with the First Person and shall include (a)
any Person who is a director or directly or indirectly the beneficial owner of
at least 10% of the


                                       14
<PAGE>

then outstanding capital stock or other equity securities of the First Person
and (b) any Person of which the First Person or an Affiliate (as defined in
clause (a) above) of the First Person shall, directly or indirectly, either
beneficially own at least 10% of the then outstanding equity securities or
constitute at least a l0% equity participant. For purposes of this
definition, "control" means, as applied to any Person, the possession,
directly or indirectly, of the power to direct or cause the direction of the
management and policies of such Person, whether through the ownership of
voting securities, by contract or otherwise, and the terms "controlling" and
"controlled" have meanings correlative to the foregoing.

        "BOARD" means the Company's Board of Directors or a committee thereof
to which any relevant decision has been duly delegated, as applicable.

        "CARRIER ONE" means Carrier One, LLC, a Delaware limited liability
company.

        "CAUSE" means with respect to a particular Management Holder (i) a
breach by such Management Holder of any employment agreement between Carrier
One, the Company or any of its Subsidiaries and such Management Holder, (ii)
any act of dishonesty, embezzlement, unauthorized use or disclosure of
Confidential Information, intellectual property, or trade secrets, common law
fraud or other fraud with respect thereto by such Management Holder, (iii)
the commission by such Management Holder of a felony, a crime involving moral
turpitude or any other act causing material harm to Carrier One, the
Company's or any of the Subsidiaries' standing or reputation, (iv) such
Management Holder's willful and continued failure to perform his duties to
Carrier One, the Company or any Subsidiary as reasonably requested by the
Board, (v) such Management Holder's willful misconduct or gross negligence,
or (vi) the willful commission by such Management Holder of an act which (a)
constitutes unfair competition with Carrier One, the Company or any of the
Subsidiaries, (b) induces any other employee to leave the employ of Carrier
One, the Company or any of the Subsidiaries or (c) induces any customer of
Carrier One, the Company or any of the Subsidiaries to breach or terminate a
contract with Carrier One, the Company or any of the Subsidiaries.

        "COMPANY" means Carrier1 International S.A., a Luxembourg SOCIETE
ANONYME, and any corporation into which it is converted or merged into.

        "CONFIDENTIAL INFORMATION" means all information, in any form or medium,
that relates to the business, products, services, research or development of
Carrier One, the Company or any of the Subsidiaries, and its and their suppliers
or


                                       15
<PAGE>

customers, including: (a) compilations of data (whether in whole or in part)
and all analyses, processes, methods, techniques, systems, formulae,
research, records, reports, manuals, documentation and models relating
thereto; (b) computer software, documentation and databases (whether existing
or in various stages of research and development); (c) identities of and
information about Carrier One, the Company's and the Subsidiaries' suppliers
and customers and their confidential information, suppliers and customers;
(d) inventions, designs, developments, devices, methods and processes
(whether or not reduced to practice); (e) internal business information,
including, without limitation, information relating to strategic and staffing
plans and practices (including information with respect to potential
acquisition targets), marketing, promotional and sales plans, practices or
programs, training practices and programs, cost and pricing structure, and
accounting and business methods; (f) all copyrightable works; and (g) all
similar or related information. Notwithstanding the immediately foregoing
sentence, the term "Confidential Information" shall not include information
with respect to a particular Management Holder which (i) becomes generally
available to the public other than as a result of disclosure by such
Management Holder, or (ii) becomes available to such Management Holder on a
non-confidential basis from a source other than Carrier One, the Company or
the Subsidiaries, or (iii) which is generally known in the telecommunications
industry and pertains to activities or business not specific to Carrier One,
the Company or any of the Subsidiaries. Information shall not be deemed to be
excluded from the meaning of "Confidential Information" merely because
individual portions or components of such information are publicly known or
available.

        "CONSENTS" means all filings, notices, licenses, consents,
authorizations, accreditations, waivers, approvals and the like.

        "GOVERNMENTAL ENTITY" means Luxembourg or any other nation, any state
or other political subdivision thereof, or any entity exercising executive,
legislative, judicial, regulatory or administrative functions of government
including any international regulatory or trade body.

        "INDIRECT OWNER" means with respect to each Person which is (i) a
corporation or any similar entity, each shareholder and each Indirect Owner
of such shareholder; (ii) a limited liability company or any similar entity,
each member and each Indirect Owner of such member; (iii) a partnership
(whether limited or general) or similar entity, each partner and each
Indirect Owner of such partner; and (iv) a trust or any similar entity, each
beneficiary who has the legal right (or whose spouse has the present legal
right) to demand a distribution of the trust's interest and each Indirect
Owner of such beneficiary or such beneficiary's spouse (whether in such
beneficiary's


                                       16
<PAGE>

capacity as a beneficiary, trustee or otherwise and whether by revocation or
amendment of such trust or otherwise).

        "INSTITUTIONAL INVESTOR" means Providence Equity Partners L.P.,
Providence Equity Partners II L.P., Primus Capital Fund IV Limited
Partnership and Primus Executive Fund Limited Partnership, and their
respective successors and assigns.

        "LLC SECURITIES" means (i) the units of any class issued by Carrier
One, (ii) any options, warrants or other rights to purchase or acquire any
units and (iii) any other equity securities issued from time to time by
Carrier One.

        "MANAGEMENT HOLDER" means each of Stig Johansson, Joachim Bauer,
Eugene A. Rizzo, Kees van Ophem, Neil Craven, Terje Nordhal, Edward Gross,
Philip Poulter, Alejandra Ancarani, Volker Weisshaar, Martin Keller, Judith
Zollinger, Jan van Veldhoven, Martin Peck, Carina Almroth, Dieter Friedrich,
Marc Gauw, Ian Cooper, Harm Werkman, Astrid Werner, Vanja Vidic, Peter
Gessler, Matthias Neumann, Christoph Mees, Nigel Findlater, Christopher
Davison, Gustav Schaefer, Teunis Florus Oskam, Jonathan Shanmuganathan, Kasim
Sheikh, Jane Townend, Isabelle Russier, Antonia Keller, Rob Hale, Linda
Clark, Gertfried Uitz, Philip Walter, Dominic McGlinchey, Heinz Bigler,
Evelien Aalberts, Rick Mikolajczuk and, if so designated, any Additional
Securityholder pursuant to SECTION 23, if applicable, and their respective
successors and assigns.

        "MANAGEMENT SECURITIES" means Securityholder Securities held by
Management Holders.

        "NON-COMPETE PERIOD" shall mean with respect to a particular
Management Holder, the period commencing on the date of this Agreement and
continuing:

(i) if such Management Holder's employment is terminated by Carrier One, the
Company or any of its Subsidiaries for Cause or by such Management Holder
voluntarily, until the end of the eighteenth month after the date of such
termination; or

(ii) if such Management Holder's employment is terminated by Carrier One, the
Company or any of its Subsidiaries not for Cause, until the earlier of (x) the
end of the eighteenth month after the date of such termination or (y) for so
long as Carrier One, the Company or any of its Subsidiaries


                                       17
<PAGE>

continues payment of such Holder's base salary (at the annual rate in effect
prior to such termination.

        "OPTION AGREEMENTS" shall mean the Option Agreements between the
Company or one or more of its Subsidiaries and each Management Holder and any
other Person who becomes a party in accordance with the terms thereof.

        "PUBLIC SALE" means any sale of Securityholder Securities in a public
offering registered under the Securities Act or to the public through a
broker, dealer or market maker pursuant to the provisions of Rule 144 adopted
under the Securities Act, or made pursuant comparable procedures under any
other applicable securities laws and regulations in any non-U.S. jurisdiction.

        "REGISTRATION RIGHTS AGREEMENT" has the meaning given such term in
the Securities Purchase Agreement.

        "RELATED AGREEMENTS" means the Articles, the Securities Purchase
Agreement, the Registration Rights Agreement and the Option Agreements.

        "SALE OF THE COMPANY" or "SALE OF THE LLC" shall mean a single
transaction or group of related transactions between the Company and/or the
Securityholders and/or the direct or indirect members or Shareholders of the
Securityholder and any Person or group of related Persons pursuant to which
such Person or group of related Persons will (i) acquire Securityholder
Securities or equity securities of Carrier One, as the case may be,
possessing the voting power to elect a majority of the Board of Directors of
the relevant company, (ii) consummate a merger or consolidation as a result
of which the Securityholders who own Securityholder Securities or other
voting securities or the members or shareholders of Carrier One who own
voting equity securities of Carrier One prior to such transaction(s) shall
own less than 50% of the voting securities of the surviving Person or its
parent or (iii) acquire (by sale, merger, consolidation or similar event) all
or substantially all of the Company's assets or the assets of Carrier One, as
applicable, (determined on a consolidated basis) including by way of a
transfer of shares of one or more Subsidiaries.

        "SECURITIES ACT" shall mean the Securities Act of 1933, as amended.

        "SECURITIES PURCHASE AGREEMENT" has the meaning given such term in
the recitals.


                                       18
<PAGE>

        "SECURITYHOLDER" has the meaning provided in the recitals, and shall
include any Additional Securityholder pursuant to SECTION 23, and their
respective successors and assigns.

        "SECURITYHOLDER SECURITIES" means (i) any Shares purchased or otherwise
acquired by any Securityholder, (ii) any options, warrants or other rights to
purchase or otherwise acquire any Shares (whether granted by the Company or a
third party) and (iii) any equity securities issued or issuable or convertible
into or exchangeable for, directly or indirectly to any of the Shares or other
securities referred to in clause (i) and (ii) above by way of a dividend or
split or exchange or in connection with a combination of Shares,
recapitalization, merger, consolidation or other reorganization. As to any
particular Securityholder Securities, such securities shall cease to be
Securityholder Securities when they have been disposed of in a Public Sale (and
otherwise in compliance with the applicable provision of this Agreement) or
repurchased by the Company or a Subsidiary.

        "SUBSIDIARY" has the meaning given such term in the Securities Purchase
Agreement.

        "TRADING VOLUME" shall mean the average weekly trading volume of
Securityholder Securities over the preceding 13-week period annualized.

        Section 11. AMENDMENT AND WAIVER. Except as otherwise provided herein,
no modification, amendment or waiver of any provision of this Agreement shall be
effective against the Company or any Securityholder unless such modification,
amendment or waiver is approved in writing by the holders of at least a majority
of the Securityholder Securities then in existence, it being understood that
such approval shall be binding upon all Securityholders; provided, that no such
amendment or action which materially adversely affects any one Securityholder,
as such, vis-a-vis the other Securityholders, as such, shall be effective
against the first Securityholder without the prior written consent of such
Securityholder. The failure of any party to enforce any of the provisions of
this Agreement shall in no way be construed as a waiver of such provisions and
shall not affect the right of such party thereafter to enforce each and every
provision of this Agreement in accordance with its terms.

        Section 12. REPRESENTATIONS AND WARRANTIES OF THE SECURITYHOLDERS. Each
Securityholder represents and warrants (as to itself but not as to any other
party) upon becoming a party hereto as follows:


                                       19
<PAGE>

        (a) INVESTMENT INTENT; SOPHISTICATED INVESTOR.  Such Securityholder
(A) is acquiring the Securityholder Securities for purposes of investment and
without a view toward distribution thereof in violation of applicable
securities laws, (B) is a sophisticated investor for purposes of applicable
U.S. federal and state securities laws and regulations, (C) acknowledges that
the Securityholder Securities have not been listed on any exchange nor
registered or qualified under the Securities Act or applicable state
securities laws or any other applicable securities laws and regulations in
any non-U.S. jurisdiction, may not be transferred absent such registration or
qualification or the availability of an exemption from registration or
qualification and (D) acknowledges that the Securityholder Securities are
speculative and illiquid and may only be transferred in compliance with all
applicable securities laws and regulations and with the approval of the Board
of Directors of the Company, and such Securityholder is in a position to bear
the risks associated therewith; provided that nothing contained in this
SECTION 12 shall prevent any Securityholder or its direct or indirect
transferee from transferring such securities in compliance with Rule 144 or
Regulation S of the Securities Act or comparable provisions of applicable
securities laws and regulations in a non-U.S. jurisdiction, and in accordance
with the provisions of the Registration Rights Agreement and this Agreement.

        (b) NO BROKER'S OR FINDER'S FEES. Such Securityholder is not
obligated to pay any broker's or finder's fees in connection with the
consummation of the transactions contemplated by the Securities Purchase
Agreement by reason of any arrangement made by the Securityholder or any of
its affiliates.

        (c) AUTHORIZATION; NO BREACH. The execution, delivery and performance of
this Agreement and the other Related Agreements to which such Securityholder is
a party have been duly authorized by or on behalf of such Securityholder. Each
Related Agreement to which such Securityholder is a party constitutes a valid
and binding obligation of such Securityholder, enforceable in accordance with
its terms, subject to bankruptcy, insolvency, liquidation, reorganization,
moratorium, fraudulent transfer, or other similar laws affecting creditor's
rights generally from time to time in effect and subject, as to enforceability,
to general principles of equity, regardless of whether such enforceability is
considered in a proceeding in equity or at law. The execution and delivery by
such Securityholder of each Related Agreement to which it is a party, and the
fulfillment of and compliance with the respective terms hereof and thereof by
such Securityholder, do not and will not (a) conflict with or result in a breach
of the terms, conditions or provisions of, (b)


                                       20
<PAGE>

result in a violation of, or (c) require any Consent that has not been
obtained or made of, from, with or to, any Person pursuant to, the
constituent documents of such Securityholder, or any material agreement,
instrument or other documents, or any applicable material requirement of law
to which such Securityholder of any Affiliate is bound or to which any of
such Persons or its assets is subject.

        (d) RECORD OWNER; PROXY. Such Securityholder (i) is or will become the
record owner of the number of Securityholder Securities notified to or agreed
with the Company on or prior to the date hereof and (ii) is not a party to any
proxy, voting trust
or other agreement which is inconsistent with, conflicts with or violates any
provision of this Agreement. No Securityholder shall grant any proxy or become
party to any voting trust or other agreement which is inconsistent with,
conflicts with or violates any provision of this Agreement.

        (e) LITIGATION. There is no action, suit, proceeding or investigation
pending, or to the best of knowledge of the Securityholder, currently
threatened, against or by such Securityholder which questions the validity of
this Agreement or any of the Related Agreements or the right of such
Securityholder to enter into any of them, or to consummate the transactions
contemplated hereby or thereby, or which might result, either individually or in
the aggregate, in any material adverse change in the assets, condition, affairs
or prospects of the Company or its Subsidiaries, financially or otherwise, nor
is such Securityholder aware that there is any basis for the foregoing. The
foregoing includes, without limitation, actions pending or threatened (or any
basis therefor known to such Securityholder) involving the prior employment of
Securityholder, or the existing or prior consulting relationships of
Securityholder, the use by such Securityholder in connection with the business
of the Company and its Subsidiaries of any information or techniques allegedly
proprietary to any of such Securityholder's prior employers or any of the
entities with which they have had or do have a consulting relationship, or their
obligations under any agreements with prior employers or under prior existing
consulting agreements. Such Securityholder has never been convicted of, plead
guilty or plead NOLO CONTENDERE to any crime other than a misdemeanor traffic
violation and during the past five years has not been a party to any civil
litigation.

        Section 13. SEVERABILITY. Whenever possible, each provision of this
Agreement shall be interpreted in such manner as to be effective and valid under


                                       21
<PAGE>

applicable law, but if any provision of this Agreement is held to be invalid,
illegal or unenforceable in any respect under any applicable law or rule in
any jurisdiction, such invalidity, illegality or unenforceability shall not
affect the validity, legality or enforceability of any other provision of
this Agreement in such jurisdiction or affect the validity, legality or
enforceability of any provision in any other jurisdiction, but this Agreement
shall be reformed, construed and enforced in such jurisdiction as if such
invalid, illegal or unenforceable provision had not been contained herein.

        Section 14. SUCCESSORS AND ASSIGNS. Except as otherwise provided
herein, this Agreement shall bind and inure to the benefit of and be
enforceable by the Company and its successors and permitted assigns and the
Securityholders and any subsequent holders of Securityholder Securities which
become a party to this Agreement and the respective successors and permitted
assigns of each of them, so long as they hold Securityholder Securities.
Carrier One may assign all or any portion of its rights or obligations under
this Agreement to any Affiliate or member of Carrier One, any Institutional
Investor or any partner of an Institutional Investor which acquires
Securityholder Securities. The Company may not assign any of its obligations
under this Agreement (other than in connection with a merger, consolidation
or other form or reorganization permitted by other sections of this
Agreement) without the written consent of the Persons holding not less than a
majority of the outstanding Securityholder Securities.

        Section 15. COUNTERPARTS. This Agreement may be executed in multiple
counterparts, each of which shall be an original and all of which taken
together shall constitute one and the same agreement.

        Section 16. REINCORPORATION, MERGER, ETC. If Carrier One shall
determine that the Company should reincorporate in another jurisdiction,
merge with or into another entity, transfer substantially all of its assets
to another entity or participate in any other corporate reorganization or
readjustment (any such transaction a "REORGANIZATION"), Securityholder shall
take such actions as may be requested by Carrier One or the Company to effect
such a Reorganization; PROVIDED that Securityholder shall not be required to
take such actions unless Securityholder's proportionate interest in the
assets and earnings of any entity that results from such Reorganization is
the same (except for de minimis differences) as such Securityholder's
interest in the assets and earnings of the Company immediately prior to such
Reorganization.

        Section 17. REMEDIES. Each party to this Agreement shall be entitled
to enforce its rights under this Agreement specifically, to recover damages
by reason


                                       22
<PAGE>

of any breach of any provision of this Agreement and to exercise all other
rights existing in its favor. The parties hereto agree and acknowledge that
money damages would not be an adequate remedy for any breach of the
provisions of the Agreement and that the Company or any Securityholder may in
its sole discretion apply to any court of law or equity or competent
jurisdiction for specific performance and/or injunctive relief (without
posting a bond or other security) in order to enforce or prevent any
violation of the provisions of this Agreement.

        Section 18. NOTICES. Any notice provided for in this Agreement shall
be in writing and shall be either personally delivered, or mailed first class
mail (postage prepaid) or sent by reputable overnight courier service
(charges prepaid) or sent by telecopy to the Company at the address set forth
below and to any other recipient at the address indicated on the Schedule
attached hereto or at such address or to the attention of such other Person
as the recipient party has specified by prior written notice to the sending
party. Notices shall be deemed to have been given hereunder when delivered
personally, when answer back is confirmed and sent by telecopy, three days
after deposit in the U.S. mail and one day after deposit with a reputable
overnight courier service.

        Carrier1 International S.A.
           c/o Carrier International GmbH
           Militarstrasse
           8004 Zurich, Switzerland
           Attention:
           Facsimile: 01/ 297 26 01
           Telephone: 01/ 297 26 00

    With a copy to:

           Carrier One, LLC
           901 Fleet Center
           50 Kennedy Plaza
           Providence RI 02903
           Attention: Glenn M. Creamer
           Facsimile: (401) 751-1790
           Telephone: (401) 751-1700

        Section 19. GOVERNING LAW; JURISDICTION. (a) This Agreement shall be
governed by, and construed in accordance with, the laws of Luxembourg, without
giving effect to any choice of law or conflict of law rules or provisions that
would cause the application of the laws of any jurisdiction other than
Luxembourg.


                                       23
<PAGE>

    (b) The courts of England have jurisdiction to hear and decide any suit,
action or proceedings, and to settle any disputes, which may arise out of or in
connection with this Agreement (respectively, "PROCEEDINGS" and "DISPUTES") and
for this purpose each party irrevocably submits to the jurisdiction of the
Courts of England.

    (c) Paragraph (b) above does not prevent any party to this Agreement from
taking proceedings relating to Proceedings or Disputes in any other courts with
jurisdiction.

    (d) Each party irrevocably waives any objection which it might at any time
have to the courts of England being nominated as the forum to hear and decide
any Proceedings and to settle any disputes and agrees not to claim that the
courts of England are not a convenient or appropriate forum.

        Section 20. DESCRIPTIVE HEADINGS; INTERPRETATION. The descriptive
headings of this Agreement are inserted for convenience only and do not
constitute a substantive part of this Agreement. Reference to any agreement,
document or instrument means such agreement, document or instrument as
amended or otherwise modified from time to time in accordance with the terms
thereof and, if applicable, hereof. The words "hereof", "herein" and
"hereunder" and words of similar import when used in this Agreement shall
refer to this Agreement as a whole and not to any particular provision of
this Agreement. Unless otherwise specified herein, the term "or" has the
inclusive meaning represented by the term "and/or" and the term "including"
is not limiting. All references as to "Sections", "Subsections", "Articles",
"Schedules" and "Exhibits" shall be to Sections, Subsections, Articles,
Schedules and Exhibits, respectively, of this Agreement unless otherwise
specifically provided.

        Section 21. NO STRICT CONSTRUCTION. The parties hereto have participated
jointly in the negotiation and drafting of this Agreement. In the event an
ambiguity or question of intent or interpretation arises, this Agreement shall
be construed as if drafted jointly by the parties hereto, and no presumption or
burden of proof shall arise favoring or disfavoring any party by virtue of the
authorship of any of the provisions of this Agreement.

        Section 22. NO THIRD PARTY BENEFICIARIES. This Agreement is not intended
to confer any rights or remedies upon any Person other than the parties hereto
and their successors and permitted assigns.


                                       24
<PAGE>

        Section 23. COMPLETE AGREEMENT. This Agreement, the Related Agreements,
those documents expressly referred to herein and other documents of even date
herewith embody the complete agreement and understanding among the parties and
supersede and preempt any prior understandings, agreements or representations by
or among the parties, written or oral, which may have related to the subject
matter hereof in any way.

        Section 24. ADDITIONAL SECURITYHOLDER. Notwithstanding the terms of
SECTION 11, an Additional Purchaser (as defined in ARTICLE XII of the Securities
Purchase Agreement) may become a party to this Agreement and shall be bound by
the terms of this Agreement upon agreement between the Company, Carrier One and
such Additional Purchaser, in which case (I) this Agreement hereof shall be
amended to reflect such Additional Purchaser as Securityholder (the "Additional
Securityholder") by a separate letter agreement signed by the Company, Carrier
One and such Additional Purchaser without further notice to the Management
Holders, and (II) where such additional Securityholder is an employee of Carrier
One, the Company and/or its Subsidiaries, such Additional Securityholder shall
be deemed to be included in the term Management Holder.

[REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]


                                       25
<PAGE>

        IN WITNESS WHEREOF, the parties hereto have executed this Agreement on
the day and year first above written.


                      CARRIER1 INTERNATIONAL S.A.


                      By: /s/ Glenn M. Creamer
                         -------------------------
                      Name:
                      Title:


                      CARRIER ONE, LLC


                      By: /s/ Glenn M. Creamer
                         -------------------------
                      Name:
                      Title:


                                       26
<PAGE>

                         /s/ Kees van Ophem
                         -------------------------
                         Kees van Ophem


[Signature page to Securityholders' Agreement]


                                       27
<PAGE>

                         /s/ Neil Craven
                         -------------------------
                         Neil Craven


[Signature page to Securityholders' Agreement]


                                       27
<PAGE>

                         /s/ Edward Gross
                         -------------------------
                         Edward Gross


[Signature page to Securityholders' Agreement]


                                       27
<PAGE>

                         /s/ Philip Poulter
                         -------------------------
                         Philip Poulter


[Signature page to Securityholders' Agreement]


                                       27
<PAGE>

                         /s/ Terje Nordahl
                         -------------------------
                         Terje Nordahl


[Signature page to Securityholders' Agreement]


                                       27
<PAGE>

                         /s/ Eugene A. Rizzo
                         -------------------------
                         Eugene A. Rizzo


[Signature page to Securityholders' Agreement]


                                       27
<PAGE>

                         /s/ Stig Johansson
                         -------------------------
                         Stig Johansson


[Signature page to Securityholders' Agreement]


                                       27

<PAGE>

                                                                   Exhibit 10.16


                                AMENDMENT NO. 1
                                       TO
                           SECURITYHOLDERS' AGREEMENT
                       AND REGISTRATION RIGHTS AGREEMENT

     This Amendment No. 1, dated as of March 1, 1999, is entered into by and
among Carrier 1 Internation S.A., a Luxembourg SOCIETE ANONYME (the
"Company"), Carrier One, LLC, a limited liability company formed under the
laws of Delaware ("Carrier One"), and the Persons listed on the signature
pages hereto (said Amendment being referred to as "this Amendment").
Capitalized terms used in this Amendment and not otherwise defined herein
shall have the meanings ascribed thereto in the Securityholders' Agreement
dated as of March 1, 1999, among the Company, Carrier One, and the
Securityholders referred to therein (the "Securityholders' Agreement") and,
or, if not defined therein, in the Registration Rights Agreement dated as of
March 1, 1999, among the Company, Carrier One, Stig Johansson, Joachim Bauer,
Eugene Rizzo, Kees van Ophern, Neil Craven, Terje Nordahl, Edward Gross, and
Philip Poulter (the "Registration Rights Agreement").

                                   WITNESSETH:

     WHEREAS, the Company, Carrier One, and certain of the Securityholders
are parties to the Securityholders' Agreement and the Registration Rights
Agreement;

     WHEREAS, Thomas Wynne and Victor Pelson may acquire Securityholder
Securities and pursuant to separate Option Agreements with the Company and,
in such event, will be subject to the rights and obligations of Management
Investors under the Registration Rights Agreement and Securityholders
Agreement;

     WHEREAS, pursuant to Section 24 of the Securityholders' Agreement,
Additional Purchasers may become a party to the Securityholders' Agreement
and shall be bound by the terms of such agreement between the Company,
Carrier One and such Additional Purchasers without further notice to the
Management Holders;

     WHEREAS, pursuant to Section 10(d) of the Registration Rights Agreement,
no consent of the holders of the Management Shares shall be required to add
additional employees and directors of the Company and its Affiliates as
parties thereto;

     WHEREAS, the Company, Carrier One, Thomas Wynne and Victor Pelson, have
agreed to amend the Securityholders' Agreement and Registration Rights
Agreement as provided herein;

<PAGE>


     NOW, THEREFORE, in consideration of the terms and conditions set forth
herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged by the parties hereto, the
parties hereto hereby agree as follows:

     SECTION 1. AMENDMENT TO SECURITYHOLDERS' AGREEMENT. Effective as of the
date hereof, the Securityholders' Agreement is hereby amended:

     In accordance with Section 24 of the Securityholders's Agreement, to add
Thomas Wynne and Victor Pelson as Securityholders and Management Holders;
Thomas Wynne and Victor Pelson hereby each agree to be bound by all of the
terms and conditions of the Securityholders' Agreement and this Amendment and
the Company and Carrier One hereby consent to Thomas Wynne and Victor Pelson
being added as Securityholders and Management Holders.

     SECTION 2. AMENDMENT TO REGISTRATION RIGHTS AGREEMENT

     In accordance with Section 10(d) of the Registration Rights Agreement,
Thomas Wynne and Victor Pelson are hereby added as Management Investors party
to the Registration Rights Agreement and agree to be bound by all of the
terms and conditions of the Registration Rights Agreement and this Amendment
and the Company and Carrier One hereby consent to Thomas Wynne and Victor
Pelson being added as Management Investor.

     SECTION 3. REPRESENTATIONS AND WARRANTIES.

     Each of the Company and Carrier One hereby represents and warrants that
(i) it has full power and authority to execute and deliver this Amendment and
to perform its obligations hereunder, (ii) it has taken all action necessary
for the execution and delivery by it of this Amendment and the performance by
it of its obligations hereunder, and (iii) this Amendment constitutes its
valid and binding obligation enforceable against it in accordance with its
terms except to the extent enforceability may be subject to bankruptcy,
insolvency, moratorium and other similar laws affecting the rights of
creditors generally or the application of principles of equity, whether in an
action at law or proceeding in equity.

     SECTION 4. REFERENCE TO AND EFFECT UPON THE AGREEMENTS.

     4.1 Except as specifically amended above, the Securityholders' Agreement
and the Registration Rights Agreement shall remain in full force and effect
and are hereby ratified and confirmed.

                                       2

<PAGE>

         4.2 The execution, delivery and effectiveness of this Amendment
shall not operate as a waiver of any right, power or remedy of any Purchaser
or Securityholders under the Securityholders' Agreement or any Management
Investor under the Registration Rights Agreement, nor constitute an amendment
of any provision of the Securityholder's Agreement or the Registration
Rights Agreement, except as specifically set forth herein.

         SECTION 5. GOVERNING LAW AND JURISDICTION

         5.1 This Amendment shall be construed and administered in accordance
with and governed by the laws of Luxembourg.

         5.2 Notwithstanding any contrary provision of the Securityholders'
Agreement or the Registration Rights Agreement, the state and federal courts
of the State of New York shall have jurisdiction to hear and decide any suit,
action or proceedings, and to settle any disputes, which may arise out of or
in connection with this Amendment or the rights or obligations of the parties
hereto under the Securityholders Agreement or the Registration Rights
Agreement (respectively, "Proceedings" and "Disputes") and for this purpose
each party irrevocably submits to the jurisdiction of such courts. This
paragraph 4.2 does not prevent any party to this Amendment from taking
proceedings relating to Proceedings or Disputes in any other courts with
jurisdiction. Each party irrevocably waives any objection which it might at
any time have to the courts located in the State of New York being nominated
as the forum to hear and decide any Proceedings and to settle any Disputes
and agrees not to claim that the courts located in the State of New York are
not a convenient or appropriate forum.

IN WITNESS WHEREOF, this Amendment has been duly executed and delivered by
the parties hereto as of the day and year first above written.


                                       3

<PAGE>

                                                  CARRIER ONE, LLC

                                                  By: /s/ Glenn M. Creamer
                                                      -----------------------
                                                      Name:  Glenn M. Creamer
                                                      Title: Chairman


                                                  CARRIER 1 INTERNATIONAL S.A.

                                                  By: /s/ Stig Johansson
                                                      -----------------------
                                                      Name: Stig Johansson
                                                      Title: Chairman

                                                  By:
                                                      -----------------------
                                                      Name:
                                                      Title:


                                                      /s/ Thomas Wynne
                                                      -----------------------
                                                          Thomas Wynne


                                                        /s/ Victor Pelson
                                                      -----------------------
                                                          Victor Pelson



                                                4


<PAGE>

                                                                   Exhibit 10.17


                              AMENDMENT NO. 2
                                    TO
                        SECURITYHOLDERS' AGREEMENT
                     AND SECURITIES PURCHASE AGREEMENT

    This Amendment No. 2, dated as of March 1, 1999, is entered into by and
among Carrier 1 International S.A., a Luxembourg SOCIETE ANONYME (the
"Company"), Carrier One, LLC, a limited liability company formed under the
laws of Delaware ("Carrier One"), and Olaf Bertschinger (said Amendment being
referred to as "this Amendment"). Capitalized terms used in this Amendment
and not otherwise defined herein shall have the meanings ascribed thereto in
the Securities Purchase Agreement, dated as of March 1, 1999 (the "Securities
Purchase Agreement"), among the Company, Carrier One, and the Purchasers
referred to therein and, or, if not defined therein, in the Securityholder's
Agreement, dated as of March 1, 1999 (the "Securityholders' Agreement"),
among the Company, Carrier One, and the Securityholders referred to therein.

                                WITNESSETH:

    WHEREAS, the Company, Carrier One, and certain of the Purchasers and
Securityholders are parties to the Securities Purchase Agreement and
Securityholders' Agreement;

    WHEREAS, Olaf Bertschinger may acquire Securityholders Securities pursuant
to a separate Option Agreement with the Company and, in such event, will be
subject to the rights and obligations of Purchasers and Securityholders under
the Securities Purchase Agreement and Securityholders' Agreement;

    WHEREAS, pursuant to Article XII of the Securities Purchase Agreement,
the Company may sell additional Equity Securities to Olaf Bertschinger as an
Additional Purchaser in accordance with the terms of said agreement, in which
case such Additional Purchaser shall by a separate letter agreement become a
part to said agreement;

    WHEREAS, pursuant to Section 24 of the Securityholders' Agreement,
Additional Purchasers may become a party to the Securityholders' Agreement
and shall be bound by the terms of such agreement upon agreement between the
Company, Carrier One and such Additional Purchasers without further notice to
the Management Holders;

    WHEREAS, the Company, Carrier One, and Olaf Bertschinger have agreed to
amend the Securities Purchase Agreement and Securityholders' Agreement as
provided herein;

<PAGE>

    NOW, THEREFORE, in consideration of the terms and conditions set forth
herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged by the parties hereto, the
parties hereto hereby agree as follows:

SECTION 1. AMENDMENT TO SECURITIES PURCHASE AGREEMENT. Effective as of the
date hereof, the Securityholders' Agreement is hereby amended in accordance
with Article XII of the Securities Purchase Agreement, to add Olaf
Bertschinger as an Additional Purchaser and a party to such agreement; Olaf
Bertschinger hereby agrees to be bound by all of the terms and conditions of
the Securities Purchase Agreement and this Amendment and the Company and
Carrier One hereby consent to Olaf Bertschinger as an Additional Purchaser.

SECTION 2. AMENDMENT TO SECURITYHOLDERS' AGREEMENT. Effective as of the date
hereof, the Securityholders' Agreement is hereby amended in accordance with
Section 24 of the Securityholders' Agreement, to add Olaf Bertschinger as
Securityholder and a party to such agreement; Olaf Bertschinger hereby agrees
to be bound by all of the terms and conditions of the Securityholders'
Agreement and this Amendment and the Company and Carrier One hereby consent
to Olaf Bertschinger being added as Securityholder.

         SECTION 3. REPRESENTATIONS AND WARRANTIES.

         Each of the Company and Carrier One hereby represents and warrants
that (i) it has full power and authority to execute and deliver this
Amendment and to perform its obligations hereunder, (ii) it has taken all
action necessary for the execution and delivery by it of this Amendment and
the performance by it of its obligations hereunder, and (iii) this Amendment
constitutes its valid and binding obligation enforceable against it in
accordance with its terms except to the extent enforceability may be subject
to bankruptcy, insolvency, moratorium and other similar laws affecting the
rights of creditors generally or the application of principles of equity,
whether in an action at law or proceeding in equity.

         SECTION 4. REFERENCE TO AND EFFECT UPON THE AGREEMENTS

         4.1 Except as specifically amended above, the Securities Purchase
Agreement and the Securityholders' Agreement shall remain in full force and
effect and are hereby ratified and confirmed.

         4.2 The execution, delivery and effectiveness of this Amendment shall
not operate as a waiver of any right, power or remedy of any Purchaser or
Securityholder under the Securities Purchase Agreement or Securityholders'
Agreement, nor constitute an amendment of any provision of the Securities
Purchase Agreement or Securityholders' Agreement, except as specifically set
forth herein.



                                        2

<PAGE>


     SECTION 5. GOVERNING LAW AND JURISDICTION

     5.1 This Amendment shall be construed and administered in accordance
with and governed by the laws of Luxembourg.

     5.2 The courts of England have jurisdiction to hear and decide any suit,
action or proceedings, and to settle any disputes, which may arise out of or
in connection with this Agreement (respectively, "PROCEEDINGS" and
"DISPUTES") and for this purpose each party irrevocably submits to the
jurisdiction of the Courts of England. This paragraph does not prevent any
party to this Agreement from taking proceedings relating to Proceedings or
Disputes in any other courts with jurisdiction. Each party irrevocably waives
any objection which it might at any time have to the courts of England being
nominated as the forum to hear and decide any Proceedings and to settle any
disputes and agrees not to claim that the courts of England are not a
convenient or appropriate forum.

IN WITNESS WHEREOF, this Amendment has been duly executed and delivered by
the parties hereto as of the day and year first above written.


                                         3

<PAGE>



                                      CARRIER ONE, LLC


                                      By:  /s/ Glenn M. Creamer
                                          -----------------------------------
                                          Name:  Glenn M. Creamer
                                          Title: Chairman



                                      CARRIER 1 INTERNATIONAL S.A.


                                      By:  /s/ Stig Johansson
                                          -----------------------------------
                                          Name:  Stig Johansson
                                          Title: Chairman



                                      By:  /s/ Glenn M. Creamer
                                          -----------------------------------
                                          Name:  Glenn M. Creamer
                                          Title:


                                          /s/ Olaf Bertschinger
                                          -----------------------------------
                                          Olaf Bertschinger


                                         4


<PAGE>

                                                                   Exhibit 10.18


                                AMENDMENT NO. 3
                                       TO
                           SECURITYHOLDERS' AGREEMENT
                       AND SECURITIES PURCHASE AGREEMENT

    This Amendment No. 3, dated as of March 1, 1999 (the "Amendment"), is
entered into by and among Carrier 1 International S.A., a Luxembourg SOCIETE
ANONYME (the "Company"), Carrier One, LLC, a limited liability company formed
under the laws of Delaware ("Carrier One"), and Fred Kaercher. Capitalized
terms used in this Amendment and not otherwise defined herein shall have the
meanings ascribed thereto in the Securityholders' Agreement, dated as of
March 1, 1999 as amended from time to time (the "Securityholders'
Agreement"), among the Company, Carrier One, and the Securityholders referred
to therein and, or, if not defined therein, in the Securities Purchase
Agreement, dated as of March 1, 1999 as amended from time to time (the
"Securities Purchase Agreement"), among the Company, Carrier One, and the
Purchasers referred to therein (the "Securities Purchase Agreement").

                                  WITNESSETH:

    WHEREAS, the Company, Carrier One, and certain of the Securityholders are
parties to the Securityholders' Agreement;

    WHEREAS, Fred Kaercher intends to purchase Securityholder Securities, and
will be subject to the rights and obligations of Management Investors under
the Securityholders Agreement;

    WHEREAS, pursuant to Section 24 of the Securityholders' Agreement,
Additional Purchasers may become a party to the Securityholders' Agreement
and shall be bound by the terms of such agreement upon agreement between the
Company, Carrier One and such Additional Purchasers without further notice to
the other Management Holders;

    WHEREAS, pursuant to Article XII of the Securities Purchase Agreement,
the Company may sell additional Equity Securities to Fred Kaercher as an
Additional Purchaser in accordance with the terms of said agreement, in which
case such Additional Purchaser shall by a separate letter agreement become a
party to said agreement;

    WHEREAS, the Company, Carrier One, and Fred Kaercher, have agreed to
amend the Securityholders' Agreement and the Securities Purchase Agreement as
provided herein;

<PAGE>

     NOW, THEREFORE, in consideration of the terms and conditions set forth
herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged by the parties hereto, the
parties hereto hereby agree as follows:

     SECTION 1. AMENDMENT TO SECURITYHOLDERS' AGREEMENT. Effective as of the
date hereof, the Securityholders' Agreement is hereby amended in accordance
with Section 24 of the Securityholders' Agreement, to add Fred Kaercher as
Securityholder and Management Holder and a party to such agreement; Fred
Kaercher hereby agrees to be bound by all of the terms and conditions of the
Securityholders' Agreement and this Amendment and the Company and Carrier One
hereby consent to Fred Kaercher being added as a Securityholder and a
Management Holder.

     SECTION 2. AMENDMENT TO SECURITIES PURCHASE AGREEMENT. Effective as of
the date hereof, the Securityholders' Agreement is hereby amended in
accordance with Article XII of the Securities Purchase Agreement, to add Fred
Kaercher as an Additional Purchaser and a party to such agreement; Fred
Kaercher hereby agrees to be bound by all of the terms and conditions of the
Securities Purchase Agreement and this Amendment and the Company and Carrier
One hereby consent to Fred Kaercher being added as an Additional Purchaser.

     SECTION 3. REPRESENTATIONS AND WARRANTIES.

     Each of the Company and Carrier One hereby represents and warrants that
(i) it has full power and authority to execute and deliver this Amendment and
to perform its obligations hereunder, (ii) it has taken all action necessary
for the execution and delivery by it of this Amendment and the performance by
it of its obligations hereunder, and (iii) this Amendment constitutes its
valid and binding obligation enforceable against it in accordance with its
terms except to the extent enforceability may be subject to bankruptcy,
insolvency, moratorium and other similar laws affecting the rights of
creditors generally or the application of principles of equity, whether in an
action at law or proceeding in equity.

     SECTION 4. REFERENCE TO AND EFFECT UPON THE AGREEMENTS.

     4.1 Except as specifically amended above, the Securityholders' Agreement
and the Securities Purchase Agreement shall remain in full force and effect
and are hereby ratified and confirmed.

     4.2 The execution, delivery and effectiveness of this Amendment shall
not operate as a waiver of any right, power or remedy of any Purchaser or
Securityholders under the Securityholders' Agreement or any Additional
Purchaser under the Securities Purchase


                                      2

<PAGE>

Agreement, nor constitute an amendment of any provision of the
Securityholders' Agreement or the Securities Purchase Agreement, except as
specifically set forth herein.

     SECTION 5. GOVERNING LAW AND JURISDICTION.

     5.1 This Agreement shall be governed by, and construed in accordance
with, the laws of Luxembourg, without giving effect to any choice of law or
conflict of law rules or provisions that would cause the application of the
laws of any jurisdiction other than Luxembourg.

     5.2 The courts of England have jurisdiction to hear and decide any suit,
action or proceedings, and to settle any disputes, which may arise out of or
in connection with this Agreement (respectively, "Proceedings" and
"Disputes") and for this purpose each party irrevocably submits to the
jurisdiction of the Courts of England.

     5.3 Paragraph 5.2 above does not prevent any party to this Agreement
from taking proceedings relating to Proceedings or Disputes in any other
courts with jurisdiction.

     5.4 Each party irrevocably waives any objection which it might at any
time have to the courts of England being nominated as the forum to hear and
decide any Proceedings and to settle any disputes and agrees not to claim
that the courts of England are not a convenient or appropriate forum.

IN WITNESS WHEREOF, this Amendment has been duly executed and delivered by
the parties hereto as of the day and year first above written.


                                      3

<PAGE>

<TABLE>
<S>                             <C>
                                CARRIER ONE, LLC

                                By:             /s/ GLENN M. CREAMER
                                       --------------------------------------
                                Name:              Glenn M. Creamer
                                Title:                  CHAIRMAN

                                CARRIER 1 INTERNATIONAL S.A.

                                By:              /s/ STIG JOHANNSON
                                       --------------------------------------
                                Name:               Stig Johannson
                                Title:                  CHAIRMAN


                                /s/ FRED KAERCHER
                                ---------------------------------------------
                                Fred Kaercher
</TABLE>





                                       4


<PAGE>

                                                                   Exhibit 10.19


                                 AMENDMENT NO. 4
                                        TO
                             SECURITYHOLDERS' AGREEMENT
                          AND SECURITIES PURCHASE AGREEMENT



     This Amendment No. 4, dated as of March 1, 1999 (the "Amendment"), is
entered into by and among Carrier 1 International S.A. a Luxembourg SOCIETE
ANONYME (the "Company"), Carrier One, LLC, a limited liability company formed
under the laws of Delaware ("Carrier One"), and Carlos Colina. Capitalized
terms used in this Amendment and not otherwise defined herein shall have the
meanings ascribed thereto in the Securityholders' Agreement, dated as of
March 1, 1999 as amended from time to time (the "Securityholders' Agreement"),
among the Company, Carrier One, and the Securityholders referred to therein
and, or, if not defined therein, in the Securities Purchase Agreement, dated
as of March 1, 1999 as amended from time to time (the "Securities Purchase
Agreement"), among the Company, Carrier One, and the Purchasers referred to
therein (the "Securities Purchase Agreement").


                             WITNESSETH:

     WHEREAS, the Company, Carrier One, and certain of the Securityholders
are parties to the Securityholders' Agreement;

     WHEREAS, Carlos Colina intends to purchase Securityholder Securities,
and will be subject to the rights and obligations of Management Investors
under the Securityholders Agreement;

     WHEREAS, pursuant to Section 24 of the Securityholders' Agreement,
Additional Purchasers may become a party to the Securityholders' Agreement
and shall be bound by the terms of such agreement upon agreement between the
Company, Carrier One and such Additional Purchasers without further notice to
the other Management Holders;

     WHEREAS, pursuant to Article XII of the Securities Purchase Agreement,
the Company may sell additional Equity Securities to Carlos Colina as an
Additional Purchaser in accordance with the terms of said agreement, in which
case such Additional Purchaser shall by a separate letter agreement become a
party to said agreement;

     WHEREAS, the Company, Carrier One, and Carlos Colina, have agreed to
amend the Securityholders' Agreement and the Securities Purchase Agreement as
provided herein.


<PAGE>

     NOW, THEREFORE, in consideration of the terms and conditions set forth
herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged by the parties hereto, the
parties hereto hereby agree as follows:

     SECTION 1. AMENDMENT TO SECURITYHOLDERS' AGREEMENT. Effective as of the
date hereof, the Securityholders' Agreement is hereby amended in accordance
with Section 24 of the Securityholders' Agreement, to add Carlos Colina as
Securityholder and Management Holder and a party to such agreement; Carlos
Colina hereby agrees to be bound by all of the terms and conditions of the
Securityholders' Agreement and this Amendment and the Company and Carrier One
hereby consent to Carlos Colina being added as a Securityholder and a
Management Holder.

     SECTION 2. AMENDMENT TO SECURITIES PURCHASE AGREEMENT. Effective as of
the date hereof, the Securityholders' Agreement is hereby amended in
accordance with Article XII of the Securities Purchase Agreement, to add
Carlos Colina as an Additional Purchaser and a party to such agreement;
Carlos Colina hereby agrees to be bound by all of the terms and conditions of
the Securities Purchase Agreement and this Amendment and the Company and
Carrier One hereby consent to Carlos Colina being added as an Additional
Purchaser.

     SECTION 3. REPRESENTATIONS AND WARRANTIES.

     Each of the Company and Carrier One hereby represents and warrants that
(i) it has full power and authority to execute and deliver this Amendment and
to perform its obligations hereunder, (ii) it has taken all action necessary
for the execution and delivery by it of this Amendment and the performance by
it of its obligations hereunder, and (iii) this Amendment constitutes its
valid and binding obligation enforceable against it in accordance with its
terms except to the extent enforceability may be subject to bankruptcy,
insolvency, moratorium and other similar laws affecting the rights of
creditors generally or the application of principles of equity, whether in an
action at law or proceeding in equity.

     SECTION 4. REFERENCE TO AND EFFECT UPON THE AGREEMENTS.

     4.1 Except as specifically amended above, the Securityholders' Agreement
and the Securities Purchase Agreement shall remain in full force and effect
and are hereby ratified and confirmed.

     4.2 The execution, delivery and effectiveness of this Amendment shall
not operate as a waiver of any right, power or remedy of any Purchaser or
Securityholders under the Securityholders' Agreement or any Additional
Purchaser under the Securities Purchase


                                     2

<PAGE>

Agreement, nor constitute an amendment of any provision of the
Securityholders' Agreement or the Securities Purchase Agreement, except as
specifically set forth herein.

             SECTION 5.  GOVERNING LAW AND JURISDICTION.

             5.1 This Agreement shall be governed by, and construed in
accordance with, the laws of Luxembourg, without giving effect to any choice
of law or conflict of law rules or provisions that would cause the
application of the laws of any jurisdiction other than Luxembourg.

             5.2 The courts of England have jurisdiction to hear and decide
any suit, action or proceedings, and do settle any disputes, which may arise
out of or in connection with this Agreement (respectively, "Proceedings" and
"Disputes") and for this purpose each party irrevocably submits to the
jurisdiction of the Courts of England.

             5.3 Paragraph 5.2 above does not prevent any party to this
Agreement from taking proceedings relating to Proceedings or Disputes in any
other courts with jurisdiction.

             5.4 Each party irrevocably waives any objection which it might
at any time have to the courts of England being nominated as the forum to
hear and decide any Proceedings and to settle any disputes and agrees not to
claim that the courts of England are not a convenient or appropriate forum.


IN WITNESS WHEREOF, this Amendment has been duly executed and delivered by
the parties hereto as of the day and year first above written.



                                3

<PAGE>

                                       CARRIER ONE, LLC


                                       By: /s/ Glenn M. Creamer
                                           ---------------------
                                       Name: Glenn M. Creamer
                                       Title: Chairman


                                       CARRIER 1 INTERNATIONAL S.A.


                                       By: /s/ Stig Johansson
                                           ---------------------
                                       Name: Stig Johansson
                                       Title: Chairman



                                       /s/ Carlos Colina
                                       ---------------------------
                                       Carlos Colina



                                     4


<PAGE>



                                                   Exhibit 23.1



INDEPENDENT AUDITORS' CONSENT

We consent to the use in this Amendment No. 3 to Registration No. 333-75195
of Carrier1 International S.A. of our report dated March 17, 1999 appearing
in the Prospectus, which is a part of such Registration Statement, and to the
reference to us under the headings "Summary Consolidated Financial Data,"
"Selected Financial Data" and "Experts" in such Prospectus.

DELOITTE & TOUCHE EXPERTA AG

/s/ DAVID WILSON                         /s/ JERRY M. MAYER
David Wilson                             Jerry M. Mayer


Erlenbach, Switzerland
June 22, 1999


<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM FINANCIAL
STATEMENTS FOR THE QUARTER ENDED MARCH 31, 1999 AND FOR THE PERIOD FROM
FEBRUARY 20, 1998 (DATE OF INCEPTION) TO DECEMBER 31, 1998 AND IS QUALIFIED IN
ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000

<S>                             <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   OTHER
<FISCAL-YEAR-END>                          DEC-31-1999             DEC-31-1998
<PERIOD-END>                               MAR-31-1999             DEC-31-1998
<CASH>                                          109406                    5702
<SECURITIES>                                    143034                       0
<RECEIVABLES>                                    12412                    2862
<ALLOWANCES>                                         0                       0
<INVENTORY>                                          0                       0
<CURRENT-ASSETS>                                229807                   14757
<PP&E>                                           41546                   31091
<DEPRECIATION>                                    2556                    1402
<TOTAL-ASSETS>                                  329777                   51434
<CURRENT-LIABILITIES>                            51294                   32245
<BONDS>                                         249608                       0
                                0                       0
                                          0                       0
<COMMON>                                         60000                   37770
<OTHER-SE>                                     (31125)                 (18581)
<TOTAL-LIABILITY-AND-EQUITY>                    329777                   51434
<SALES>                                          12293                    2792
<TOTAL-REVENUES>                                 12293                    2792
<CGS>                                                0                       0
<TOTAL-COSTS>                                    21669                   22055
<OTHER-EXPENSES>                                  2428                    (53)
<LOSS-PROVISION>                                     0                       0
<INTEREST-EXPENSE>                                4205                      11
<INCOME-PRETAX>                                (15030)                 (19235)
<INCOME-TAX>                                         0                       0
<INCOME-CONTINUING>                            (15030)                 (19235)
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                                   (15030)                 (19235)
<EPS-BASIC>                                   (0.53)                  (2.61)
<EPS-DILUTED>                                   (0.53)                  (2.61)


</TABLE>

<PAGE>
                                                                    EXHIBIT 99.1

                             LETTER OF TRANSMITTAL
                          CARRIER1 INTERNATIONAL S.A.

                         Offer to Exchange all Outstanding
                    13 1/4% Senior Dollar Notes Due 2009 and
                 13 1/4% Senior Euro Notes Due 2009 (DTC Held)
                                      for
                    13 1/4% Senior Dollar Notes Due 2009 and
                 13 1/4% Senior Euro Notes Due 2009 (DTC Held)
                        which Have Been Registered Under
                           the Securities Act of 1933
              Pursuant to the Prospectus, dated             , 1999

- --------------------------------------------------------------------------------
    THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY TIME, ON
          , 1999 UNLESS EXTENDED (THE "EXPIRATION DATE"). TENDERS MAY BE
   WITHDRAWN PRIOR TO 5:00 P.M., NEW YORK CITY TIME, ON THE EXPIRATION DATE.
- --------------------------------------------------------------------------------

             DELIVERY TO: The Chase Manhattan Bank, EXCHANGE AGENT

<TABLE>
<S>                                            <C>
          BY MAIL, HAND DELIVERY OR                        FOR INFORMATION CALL:
             OVERNIGHT CARRIER:                               (212) 946-3172

          The Chase Manhattan Bank                    FACSIMILE TRANSMISSION NUMBER:
     Capital Markets Fiduciary Services                      (212) 946-8177/78
            450 West 33rd Street
                 15th Floor                                CONFIRM BY TELEPHONE:
          New York, New York 10001                            (212) 946-3172
          Attention: William Potes
</TABLE>

DELIVERY OF THIS LETTER OF TRANSMITTAL TO AN ADDRESS OTHER THAN AS SET FORTH
     ABOVE, OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE OTHER THAN AS
             SET FORTH ABOVE, WILL NOT CONSTITUTE A VALID DELIVERY.

                 PLEASE READ THIS ENTIRE LETTER OF TRANSMITTAL
                   CAREFULLY BEFORE COMPLETING ANY BOX BELOW
<PAGE>
    The undersigned acknowledges that he, she or it has received and reviewed
this Letter of Transmittal (the "Letter") and the Prospectus, dated         ,
1999 (the "Prospectus"), of Carrier1 International S.A., a societe anonyme
organized under the laws of the Grand Duchy of Luxembourg (the "Company" or the
"Issuer"), relating to its offer to exchange (i) up to $160,000,000 aggregate
principal amount of its 13 1/4% Senior Dollar Notes Due 2009 (the "New Dollar
Notes"), which have been registered under the Securities Act of 1933, as amended
(the "Securities Act"), for a like principal amount of its issued and
outstanding 13 1/4% Senior Dollar Notes Due 2009 (the "Old Dollar Notes") from
the registered holders thereof (the "Dollar Note Holders") and (ii) its 13 1/4%
Senior Euro Notes Due 2009 (the "New Euro Notes"), which have been registered
under the Securities Act, for a like principal amount of its issued and
outstanding 13 1/4% Senior Euro Notes Due 2009 (the "Old Euro Notes"). The
Prospectus and this Letter together constitute the Company's offer to exchange
(the "Exchange Offer") (i) its New Dollar Notes for a like principal amount of
its Old Dollar Notes from the registered holders thereof (the "Dollar Note
Holders") and (ii) its New Euro Notes which are to be deposited with a custodian
for, and registered in the name of, The Depository Trust Company ("DTC") or its
nominee (the "New DTC Euro Notes") for a like principal amount of Old Euro Notes
which have been deposited with a custodian for, and registered in the name of,
DTC or its nominee (the "Old DTC Euro Notes") from the registered holders
thereof (the "DTC Euro Note Holders" and, together with the Dollar Note Holders,
the "Holders"). For the purposes of this Letter, the New Dollar Notes and the
New DTC Euro Notes are collectively referred to as the "New Notes," and the Old
Dollar Notes and the Old DTC Euro Notes are collectively referred to as the "Old
Notes."

    For each Old Note accepted for exchange, the Holder of such Old Note will
receive a New Note having a principal amount equal to that of the surrendered
Old Note. The New Notes will bear interest from the most recent date to which
interest has been paid on the Old Notes or, if no interest has been paid on the
Old Notes, from February 19, 1999. Accordingly, registered Holders of New Notes
on the relevant record date for the first interest payment date following the
consummation of the Exchange Offer will receive interest accruing from the most
recent date to which interest has been paid or, if no interest has been paid,
from February 19, 1999. Old Notes accepted for exchange will cease to accrue
interest from and after the date of consummation of the Exchange Offer. Holders
of Old Notes whose Old Notes are accepted for exchange will not receive any
payment in respect of accrued interest on such Old Notes otherwise payable on
any interest payment date the record date for which occurs on or after
consummation of the Exchange Offer.

    This Letter is to be completed by a Holder of Old Notes either if
certificates are to be forwarded herewith or if a tender of certificates for Old
Notes, if available, is to be made by book-entry transfer to the account
maintained by the Exchange Agent at DTC (the "Book-Entry Transfer Facility")
pursuant to the procedures set forth in "The Exchange Offer--Book-Entry
Transfer" section of the Prospectus. Holders of Old Notes whose certificates are
not immediately available, or who are unable to deliver their certificates or
confirmation of the book-entry tender of their Old Notes into the Exchange
Agent's account at the Book-Entry Transfer Facility (a "Book-Entry
Confirmation") and all other documents required by this Letter to the Exchange
Agent on or prior to the Expiration Date, must tender their Old Notes according
to the guaranteed delivery procedures set forth in "The Exchange
Offer--Guaranteed Delivery Procedures" section of the Prospectus. See
Instruction 1. Delivery of documents to the Book-Entry Transfer Facility does
not constitute delivery to the Exchange Agent.
<PAGE>
    List below the Old Notes to which this Letter relates. If the space provided
below is inadequate, the certificate numbers and principal amount of Old Notes
should be listed on a separate signed schedule affixed hereto.

<TABLE>
<CAPTION>
- -----------------------------------------------------------------------------------------------------
                                      DESCRIPTION OF OLD NOTES
- -----------------------------------------------------------------------------------------------------
                                                          (1)              (2)              (3)
                                                                        AGGREGATE
             NAME(S) AND ADDRESS(ES)                                    PRINCIPAL        PRINCIPAL
             OF REGISTERED HOLDER(S)                  CERTIFICATE       AMOUNT OF         AMOUNT
            (PLEASE FILL IN, IF BLANK)                NUMBER(S)*       OLD NOTE(S)      TENDERED**
<S>                                                 <C>              <C>              <C>
- -----------------------------------------------------------------------------------------------------

                                                    -------------------------------------------------

                                                    -------------------------------------------------

                                                    -------------------------------------------------
                                                         TOTAL
- -----------------------------------------------------------------------------------------------------
</TABLE>

*   Need not be completed if Old Notes are being tendered by book-entry
    transfer.

**  Unless otherwise indicated in this column, a holder will be deemed to have
    tendered ALL of the Old Notes represented by the Old Notes indicated in
    column 2. See Instruction 2. Old Notes tendered hereby must be in
    denominations of principal amount of $1,000 or [EURO]1,000, as applicable,
    and any integral multiple thereof. See Instruction 1.

/ /  CHECK HERE IF TENDERED OLD NOTES ARE BEING DELIVERED BY BOOK-ENTRY TRANSFER
    MADE TO THE ACCOUNT MAINTAINED BY THE EXCHANGE AGENT WITH THE BOOK-ENTRY
    TRANSFER FACILITY AND COMPLETE THE FOLLOWING:

    Name of Tendering Institution ______________________________________________
    Account Number _____________________________________________________________
    Transaction Code Number ____________________________________________________
/ /  CHECK HERE IF TENDERED OLD NOTES ARE BEING DELIVERED PURSUANT TO A NOTICE
    OF GUARANTEED DELIVERY PREVIOUSLY SENT TO THE EXCHANGE AGENT AND COMPLETE
    THE FOLLOWING:

    Name(s) of Registered Holder(s) ____________________________________________
    Window Ticket Number (if any) ______________________________________________
    Date of Execution of Notice of Guaranteed Delivery _________________________
    Name of Institution Which Guaranteed Delivery ______________________________
    IF DELIVERED BY BOOK-ENTRY TRANSFER, COMPLETE THE FOLLOWING:

    Account Number _____________________________________________________________
    Transaction Code Number ____________________________________________________
/ /  CHECK HERE IF YOU ARE A BROKER-DEALER ENTITLED, PURSUANT TO THE TERMS OF
    THE REGISTRATION RIGHTS AGREEMENT REFERRED TO IN THE PROSPECTUS, TO RECEIVE,
    AND WISH TO RECEIVE, 10 ADDITIONAL COPIES OF THE PROSPECTUS AND 10 COPIES OF
    ANY AMENDMENTS OR SUPPLEMENTS THERETO WITHIN 90 DAYS AFTER THE EXPIRATION
    DATE.

    Name: ______________________________________________________________________
    Address: ___________________________________________________________________

    If the undersigned is not a broker-dealer, the undersigned represents that
it is not engaged in, and does not intend to engage in, a distribution of New
Notes. If the undersigned is a broker-dealer that will receive New Notes for its
own account in exchange for Old Notes that were acquired as a result of
market-making activities or other trading activities, it acknowledges and
represents that it will deliver a prospectus meeting the requirements of the
Securities Act, in connection with any resale of such New Notes; however, by so
acknowledging and representing and by delivering such a prospectus the
undersigned will not be deemed to admit that it is an "underwriter" within the
meaning of the Securities Act. If the undersigned is a broker-dealer that will
receive New Notes, it represents that the Old Notes to be exchanged for the New
Notes were acquired as a result of market-making activities or other trading
activities. In addition, such broker-dealer represents that it is not acting on
behalf of any person who could not truthfully make the foregoing
representations.
<PAGE>
              PLEASE READ THE ACCOMPANYING INSTRUCTIONS CAREFULLY

    Ladies and Gentlemen:

    Upon the terms and subject to the conditions of the Exchange Offer, the
undersigned hereby tenders to the Company the aggregate principal amount of Old
Notes indicated above. Subject to, and effective upon, the acceptance for
exchange of the Old Notes tendered hereby, the undersigned hereby sells, assigns
and transfers to, or upon the order of, the Company all right, title and
interest in and to such Old Notes as are being tendered hereby.

    The undersigned hereby irrevocably constitutes and appoints the Exchange
Agent as the undersigned's true and lawful agent and attorney-in-fact with
respect to such tendered Old Notes, with full power of substitution, among other
things, to cause the Old Notes to be assigned, transferred and exchanged. The
undersigned hereby represents and warrants that the undersigned has full power
and authority to tender, sell, assign and transfer the Old Notes, and to acquire
New Notes issuable upon the exchange of such tendered Old Notes, and that, when
such Old Notes are accepted for exchange, the Company will acquire good and
unencumbered title thereto, free and clear of all liens, restrictions, charges
and encumbrances and not subject to any adverse claim when the same are accepted
by the Company. The undersigned hereby further represents and warrants that any
New Notes acquired in exchange for Old Notes tendered hereby will have been
acquired in the ordinary course of business of the person receiving such New
Notes, whether or not such person is the undersigned, that neither the Holder of
such Old Notes nor any such other person is participating in, intends to
participate in or has an arrangement or understanding with any person to
participate in the distribution (within the meaning of the Securities Act) of
Old Notes or New Notes, that neither the Holder of such Old Notes nor any such
other person is an "affiliate," as defined in Rule 405 under the Securities Act,
of the Company, and that neither the Holder of such Old Notes nor such other
person is acting on behalf of any person who could not truthfully make the
foregoing representations and warranties.

    The undersigned acknowledges that this Exchange Offer is being made in
reliance on interpretations by the staff of the Securities and Exchange
Commission (the "SEC"), as set forth in no-action letters issued to third
parties, that the New Notes issued pursuant to the Exchange Offer in exchange
for the Old Notes may be offered for resale, resold and otherwise transferred by
Holders thereof (other than any such Holder that is a broker-dealer or an
"affiliate" of the Company within the meaning of Rule 405 under the Securities
Act), without compliance with the registration and prospectus delivery
provisions of the Securities Act, provided that such New Notes are acquired in
the ordinary course of such Holder's business, at the time of commencement of
the Exchange Offer such Holder has no arrangement or understanding with any
person to participate in a distribution of such New Notes, and such Holder is
not engaged in, and does not intend to engage in, a distribution of such New
Notes. However, the SEC has not considered the Exchange Offer in the context of
a no-action letter and there can be no assurance that the staff of the SEC would
make a similar determination with respect to the Exchange Offer as in other
circumstances. If the undersigned is not a broker-dealer, the undersigned
represents that it is not engaged in, and does not intend to engage in, a
distribution of New Notes and has no arrangement or understanding to participate
in a distribution of New Notes. If the undersigned is a broker-dealer that will
receive New Notes for its own account in exchange for Old Notes, it represents
that the Old Notes to be exchanged for the New Notes were acquired by it as a
result of market-making activities or other trading activities and acknowledges
that it will deliver a prospectus meeting the requirements of the Securities Act
in connection with any resale of such New Notes; however, by so acknowledging
and by delivering a prospectus meeting the requirements of the Securities Act,
the undersigned will not be deemed to admit that it is an "underwriter" within
the meaning of the Securities Act.

    The SEC has taken the position that such broker-dealers may fulfill their
prospectus delivery requirements with respect to the New Notes (other than a
resale of New Notes received in exchange for an unsold allotment from the
original sale of the Old Notes) with the Prospectus. The Prospectus, as it may
be amended or supplemented from time to time, may be used by certain
broker-dealers (as specified in the Registration Rights Agreement referenced in
the Prospectus) ("Participating Broker-Dealers") for a period of time, starting
on the Expiration Date and ending on the close of business 90 days after the
<PAGE>
Expiration Date in connection with the sale or transfer of such New Notes. The
Company has agreed that, for such period of time, it will make the Prospectus
(as it may be amended or supplemented) available to such a broker-dealer which
elects to exchange Old Notes, acquired for its own account as a result of market
making or other trading activities, for New Notes pursuant to the Exchange Offer
for use in connection with any resale of such New Notes. By accepting the
Exchange Offer, each broker-dealer that receives New Notes pursuant to the
Exchange Offer acknowledges and agrees to notify the Company prior to using the
Prospectus in connection with the sale or transfer of New Notes and that, upon
receipt of notice from the Company of the happening of any event which makes any
statement in the Prospectus untrue in any material respect or which requires the
making of any changes in the Prospectus in order to make the statements therein
(in light of the circumstances under which they were made) not misleading, such
broker-dealer will suspend use of the Prospectus until (i) the Company has
amended or supplemented the Prospectus to correct such misstatement or omission
and (ii) either the Company has furnished copies of the amended or supplemented
Prospectus to such broker-dealer or, if the Company has not otherwise agreed to
furnish such copies and declines to do so after such broker-dealer so requests,
such broker-dealer has obtained a copy of such amended or supplemented
Prospectus as filed with the SEC. Except as described above, the Prospectus may
not be used for or in connection with an offer to resell, a resale or any other
retransfer of New Notes. A broker-dealer that acquired Old Notes in a
transaction other than as part of its market-making activities or other trading
activities will not be able to participate in the Exchange Offer.

    The undersigned will, upon request, execute and deliver any additional
documents deemed by the Company to be necessary or desirable to complete the
sale, assignment and transfer of the Old Notes tendered hereby. All authority
conferred or agreed to be conferred in this Letter and every obligation of the
undersigned hereunder shall be binding upon the successors, assigns, heirs,
executors, administrators, trustees in bankruptcy and legal representatives of
the undersigned and shall not be affected by, and shall survive, the death or
incapacity of the undersigned. This tender may be withdrawn only in accordance
with the procedures set forth in "The Exchange Offer--Withdrawal of Tenders"
section of the Prospectus.

    Unless otherwise indicated herein in the box entitled "Special Issuance
Instructions" below, please deliver the New Notes (and, if applicable,
substitute certificates representing Old Notes for any Old Notes not exchanged)
in the name of the undersigned or, in the case of a book-entry delivery of Old
Notes, please credit the account indicated above maintained at the Book-Entry
Transfer Facility. Similarly, unless otherwise indicated under the box entitled
"Special Delivery Instructions" below, please send the New Notes (and, if
applicable, substitute certificates representing Old Notes for any Old Notes not
exchanged) to the undersigned at the address shown above in the box entitled
"Description of Old Notes."

    THE UNDERSIGNED, BY COMPLETING THE BOX ENTITLED "DESCRIPTION OF OLD NOTES"
ABOVE AND SIGNING THIS LETTER, WILL BE DEEMED TO HAVE TENDERED THE OLD NOTES AS
SET FORTH IN SUCH BOX ABOVE.

                 PLEASE READ THIS ENTIRE LETTER OF TRANSMITTAL
                   CAREFULLY BEFORE COMPLETING ANY BOX ABOVE.
<PAGE>
- --------------------------------------------------------------------------------

                                PLEASE SIGN HERE
                   (TO BE COMPLETED BY ALL TENDERING HOLDERS)

  x ___________________________________________________________________ , 1999

  x ___________________________________________________________________ , 1999

  ____________________________________________________________________________
             Signature(s) of Owner                              Date

  Area Code and Telephone Number _____________________________________________

      If a Holder is tendering an Old Note, this Letter must be signed by the
  registered Holder(s) as the name(s) appear(s) on the certificate(s) for the
  Old Note or by any person(s) authorized to become registered Holder(s) by
  endorsements and documents transmitted herewith. If signature is by a
  trustee, executor, administrator, guardian, officer or other person acting
  in a fiduciary or representative capacity, please set forth full title. See
  Instruction 3.

  Name(s) ____________________________________________________________________
  ____________________________________________________________________________
                             (PLEASE TYPE OR PRINT)

  Capacity: __________________________________________________________________

  Address: ___________________________________________________________________
  ____________________________________________________________________________
  ____________________________________________________________________________
  ____________________________________________________________________________

                              SIGNATURE GUARANTEE
                         (IF REQUIRED BY INSTRUCTION 3)

  SIGNATURE(S) GUARANTEED BY _________________________________________________

  AN ELIGIBLE INSTITUTION: ___________________________________________________
                             (AUTHORIZED SIGNATURE)

   __________________________________________________________________________
                                    (TITLE)

   __________________________________________________________________________
                                (NAME AND FIRM)

  DATED: ______________________________________________________________ , 1999

   (PLEASE COMPLETE ACCOMPANYING SUBSTITUTE FORM W-9 HEREIN. SEE INSTRUCTION
                                      5.)

- --------------------------------------------------------------------------------
<PAGE>
- -------------------------------------------

                         SPECIAL ISSUANCE INSTRUCTIONS
                         (SEE INSTRUCTIONS 3, 4 AND 6)

      To be completed ONLY if certificates for Old Notes not exchanged and/or
  New Notes are to be issued in the name of and sent to someone other than the
  person or persons whose signature(s) appear(s) on this Letter above, or if
  Old Notes delivered by book-entry transfer which are not accepted for
  exchange are to be returned by credit to an account maintained at the
  Book-Entry Transfer Facility other than the account indicated above.

  Issue: New Notes and/or Old Notes to:
  Name(s) ____________________________________________________________________
                             (PLEASE TYPE OR PRINT)
    _________________________________________________________________________
                             (PLEASE TYPE OR PRINT)

  Address ____________________________________________________________________

  ____________________________________________________________________________

  ____________________________________________________________________________
                                   (ZIP CODE)

   __________________________________________________________________________
                         (COMPLETE SUBSTITUTE FORM W-9)

  / / Credit unexchanged Old Notes delivered by book-entry transfer to the
      Book-Entry Transfer Facility account set forth below.

      ________________________________________________________________________
                           (BOOK-ENTRY TRANSFER FACILITY
                          ACCOUNT NUMBER, IF APPLICABLE)

- ------------------------------------------------------
- ------------------------------------------------------

                         SPECIAL DELIVERY INSTRUCTIONS
                         (SEE INSTRUCTIONS 3, 4 AND 6)

      To be completed ONLY if certificates for Old Notes not exchanged and/or
  New Notes are to be sent to someone other than the person or persons whose
  signature(s) appear(s) on this Letter above or to such person or persons at
  an address other than shown in the box entitled "Description of Old Notes"
  on this Letter above.

  Mail: New Notes and/or Old Notes to:

  Name(s) ____________________________________________________________________
                             (PLEASE TYPE OR PRINT)

    _________________________________________________________________________
                             (PLEASE TYPE OR PRINT)

  Address ____________________________________________________________________

  ____________________________________________________________________________

  ____________________________________________________________________________
                                   (ZIP CODE)

- -----------------------------------------------------

IMPORTANT: UNLESS GUARANTEED DELIVERY PROCEDURES ARE COMPLIED WITH, THIS LETTER
OR A FACSIMILE HEREOF (TOGETHER WITH THE CERTIFICATES FOR OLD NOTES OR A
BOOK-ENTRY CONFIRMATION AND ALL OTHER REQUIRED DOCUMENTS) MUST BE RECEIVED BY
THE EXCHANGE AGENT PRIOR TO 5:00 P.M., NEW YORK CITY TIME, ON THE EXPIRATION
DATE.
<PAGE>
                                  INSTRUCTIONS
     FORMING PART OF THE TERMS AND CONDITIONS OF THE EXCHANGE OFFER FOR THE
13 1/4% SENIOR DOLLAR NOTES DUE 2009 AND 13 1/4% SENIOR EURO NOTES DUE 2009 (DTC
                                     HELD)
               OF CARRIER1 INTERNATIONAL S.A. IN EXCHANGE FOR THE
13 1/4% SENIOR DOLLAR NOTES DUE 2009 AND 13 1/4% SENIOR EURO NOTES DUE 2009 (DTC
                                     HELD)
      OF CARRIER1 INTERNATIONAL S.A., WHICH HAVE BEEN REGISTERED UNDER THE
                       SECURITIES ACT OF 1933, AS AMENDED

1.  DELIVERY OF THIS LETTER AND NOTES; GUARANTEED DELIVERY PROCEDURES.

    This Letter is to be completed by Holders of Old Notes either if
certificates are to be forwarded herewith or if tenders are to be made pursuant
to the procedures for delivery by book-entry transfer set forth in "The Exchange
Offer--Book-Entry Transfer" section of the Prospectus. Certificates for all
physically tendered Old Notes, or Book-Entry Confirmation, as the case may be,
as well as a properly completed and duly executed Letter (or manually signed
facsimile hereof) and any other documents required by this Letter, must be
received by the Exchange Agent at the address set forth herein on or prior to
the Expiration Date, or the tendering Holder must comply with the guaranteed
delivery procedures set forth below. Old Notes tendered hereby must be in
denominations of principal amount of $1,000 or [EURO]1,000, as applicable, and
any integral multiple thereof.

    Holders whose certificates for Old Notes are not immediately available or
who cannot deliver their certificates and all other required documents to the
Exchange Agent on or prior to the Expiration Date, or who cannot complete the
procedure for book entry transfer on a timely basis, may tender their Old Notes
pursuant to the guaranteed delivery procedures set forth in "The Exchange
Offer--Guaranteed Delivery Procedures" section of the Prospectus. Pursuant to
such procedures, (i) such tender must be made through an Eligible Institution,
(ii) prior to 5:00 P.M., New York City time, on the Expiration Date, the
Exchange Agent must receive from such Eligible Institution a properly completed
and duly executed Letter (or a facsimile thereof) and Notice of Guaranteed
Delivery, substantially in the form provided by the Company (by facsimile
transmission, mail or hand delivery), setting forth the name and address of the
Holder of Old Notes and the amount of Old Notes tendered, stating that the
tender is being made thereby and guaranteeing that within three New York Stock
Exchange ("NYSE") trading days after the date of execution of the Notice of
Guaranteed Delivery, the certificates for all physically-tendered Old Notes, in
proper form for transfer, or a Book-Entry Confirmation, as the case may be, and
any other documents required by this Letter will be deposited by the Eligible
Institution with the Exchange Agent, and (iii) the certificates for all
physically-tendered Old Notes, in proper form for transfer, or a Book-Entry
Confirmation, as the case may be, and all other documents required by this
Letter, are received by the Exchange Agent within three NYSE trading days after
the date of execution of the Notice of Guaranteed Delivery.

    The method of delivery of this Letter, the Old Notes and all other required
documents is at the election and risk of the tendering Holders, but the delivery
will be deemed made only when actually received or confirmed by the Exchange
Agent. If Old Notes are sent by mail, it is suggested that the mailing be
registered mail, properly insured, with return receipt requested, made
sufficiently in advance of the Expiration Date to permit delivery to the
Exchange Agent prior to 5:00 P.M., New York City time, on the Expiration Date.

    See "The Exchange Offer" section of the Prospectus.

2.  PARTIAL TENDERS (NOT APPLICABLE TO NOTEHOLDERS WHO TENDER BY BOOK-ENTRY
    TRANSFER).

    If less than all of the Old Notes evidenced by a submitted certificate are
to be tendered, the tendering Holder(s) should fill in the aggregate principal
amount of Old Notes to be tendered in the box above entitled "Description of Old
Notes--Principal Amount Tendered." A reissued certificate representing the
balance of nontendered Old Notes will be sent to such tendering Holder, unless
otherwise provided in the appropriate box on this Letter, promptly after the
Expiration Date. ALL OF THE OLD NOTES DELIVERED TO THE EXCHANGE AGENT WILL BE
DEEMED TO HAVE BEEN TENDERED UNLESS OTHERWISE INDICATED.
<PAGE>
3.  SIGNATURES ON THIS LETTER; BOND POWERS AND ENDORSEMENTS; GUARANTEE OF
    SIGNATURES.

    If this Letter is signed by the registered Holder of the Old Notes tendered
hereby, the signature must correspond exactly with the name as written on the
face of the certificates without any change whatsoever.

    If any tendered Old Notes are owned of record by two or more joint owners,
all of such owners must sign this Letter.

    If any tendered Old Notes are registered in different names on several
certificates, it will be necessary to complete, sign and submit as many separate
copies of this Letter as there are different registrations of certificates.

    When this Letter is signed by the registered Holder or Holders of the Old
Notes specified herein and tendered hereby, no endorsements of certificates or
separate bond powers are required. If, however, the New Notes are to be issued,
or any untendered Old Notes are to be reissued, to a person other than the
registered Holder, then endorsements of any certificates transmitted hereby or
separate bond powers are required. Signatures on such certificate(s) must be
guaranteed by an Eligible Institution.

    If this Letter is signed by a person other than the registered Holder or
Holders of any certificate(s) specified herein, such certificate(s) must be
endorsed or accompanied by appropriate bond powers, in either case signed
exactly as the name or names of the registered Holder or Holders appear(s) on
the certificate(s) and signatures on such certificate(s) must be guaranteed by
an Eligible Institution.

    If this Letter or any certificates or bond powers are signed by trustees,
executors, administrators, guardians, attorneys-in-fact, officers of
corporations or others acting in a fiduciary or representative capacity, such
persons should so indicate when signing, and, unless waived by the Company,
proper evidence satisfactory to the Company of their authority to so act must be
submitted.

    ENDORSEMENTS ON CERTIFICATES FOR OLD NOTES OR SIGNATURES ON BOND POWERS
REQUIRED BY THIS INSTRUCTION 3 MUST BE GUARANTEED BY ANY MEMBER FIRM OF A
REGISTERED NATIONAL SECURITIES EXCHANGE OR OF THE NATIONAL ASSOCIATION OF
SECURITIES DEALERS, INC., A COMMERCIAL BANK OR TRUST COMPANY HAVING AN OFFICE OR
CORRESPONDENT IN THE UNITED STATES OR AN "ELIGIBLE GUARANTOR INSTITUTION" WITHIN
THE MEANING OF RULE 17AD-15 UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS
AMENDED (EACH AN "ELIGIBLE INSTITUTION").

    SIGNATURES ON THIS LETTER NEED NOT BE GUARANTEED BY AN ELIGIBLE INSTITUTION,
PROVIDED THE OLD NOTES ARE TENDERED: (I) BY A REGISTERED HOLDER OF OLD NOTES
(WHICH TERM, FOR PURPOSES OF THE EXCHANGE OFFER, INCLUDES ANY PARTICIPANT IN THE
BOOK-ENTRY TRANSFER FACILITY SYSTEM WHOSE NAME APPEARS ON A SECURITY POSITION
LISTING AS THE HOLDER OF SUCH OLD NOTES) WHO HAS NOT COMPLETED THE BOX ENTITLED
"SPECIAL ISSUANCE INSTRUCTIONS" OR "SPECIAL DELIVERY INSTRUCTIONS" IN THIS
LETTER, OR (II) FOR THE ACCOUNT OF AN ELIGIBLE INSTITUTION.

4.  SPECIAL ISSUANCE AND DELIVERY INSTRUCTIONS.

    Tendering Holders of Old Notes should indicate in the applicable box the
name and address to which New Notes issued pursuant to the Exchange Offer and or
substitute certificates evidencing Old Notes not exchanged are to be issued or
sent, if different from the name or address of the person signing this Letter.
In the case of issuance in a different name, the employer identification or
social security number of the person named must also be indicated. Holders
tendering Old Notes by book-entry transfer may request that Old Notes not
exchanged be credited to such account maintained at the Book-Entry Transfer
Facility as such Holder may designate hereon. If no such instructions are given,
such Old Notes not exchanged will be returned to the name and address of the
person signing this Letter.

5.  TAXPAYER IDENTIFICATION NUMBER.

    Federal income tax law generally requires that a tendering Holder whose Old
Notes are accepted for exchange must provide the Company (as payor), or the
Paying Agent designated by the Company to act on its behalf, with such Holder's
correct Taxpayer Identification Number ("TIN") on Substitute Form W-9 below,
which in the case of a tendering Holder who is an individual, is his or her
social security number. If the Company is not provided with the current TIN or
an adequate basis for an exemption from backup
<PAGE>
withholding, such tendering Holder may be subject to a $50 penalty imposed by
the Internal Revenue Service. In addition, delivery to such tendering Holder of
New Notes may result in backup withholding in an amount equal to 31% of all
reportable payments made after the exchange. If withholding results in an
overpayment of taxes, a refund may be obtained.

    Exempt Holders of Old Notes (including, among others, all corporations and
certain foreign individual) are not subject to these backup withholding and
reporting requirements. See the enclosed Guidelines of Certification of Taxpayer
Identification Number on Substitute Form W-9 (the "W-9 Guidelines") for
additional instructions.

    To prevent backup withholding, each tendering Holder of Old Notes must
provide its correct TIN by completing the Substitute Form W-9 set forth below,
certifying, under penalties of perjury, that the TIN provided is correct (or
that such Holder is awaiting a TIN) and that (i) the Holder is exempt from
backup withholding, or (ii) the Holder has not been notified by the Internal
Revenue Service that such Holder is subject to backup withholding as a result of
a failure to report all interest or dividends or (iii) the Internal Revenue
Service has notified the Holder that such Holder is no longer subject to backup
withholding. If the tendering Holder of Old Notes is a nonresident alien or
foreign entity not subject to backup withholding, such Holder must give the
Exchange Agent a completed Form W-8, Certificate of Foreign Status. This form
may be obtained from the Exchange Agent. If the Old Notes are in more than one
name or are not in the name of the actual owner, such Holder should consult the
W-9 Guidelines for information on which TIN to report. If such Holder does not
have a TIN, such Holder should consult the W-9 Guidelines for instructions on
applying for a TIN, check the box in Part 2 of the Substitute Form W-9 and write
"applied for" in lieu of its TIN. Note: Checking this box and writing "applied
for" on the form means that such Holder has already applied for a TIN or that
such Holder intends to apply for one in the near future. If such Holder does not
provide its TIN to the Issuer within 60 days, backup withholding will begin and
continue until such Holder furnishes its TIN to the Issuer.

6.  TRANSFER TAXES.

    The Company will pay all transfer taxes, if any, applicable to the transfer
of Old Notes to it or its order pursuant to the Exchange Offer. If, however, New
Notes and/or substitute Old Notes not exchanged are to be delivered to, or are
to be registered or issued in the name of, any person other than the registered
Holder of the Old Notes tendered hereby, or if tendered Old Notes are registered
in the name of any person other than the person signing this Letter, or if a
transfer tax is imposed for any reason other than the transfer of Old Notes to
the Company or its order pursuant to the Exchange Offer, the amount of any such
transfer taxes (whether imposed on the registered Holder or any other persons)
will be payable by the tendering Holder. If satisfactory evidence of payment of
such taxes or exemption therefrom is not submitted herewith, the amount of such
transfer taxes will be billed directly to such tendering Holder.

    EXCEPT AS PROVIDED IN THIS INSTRUCTION 6, IT WILL NOT BE NECESSARY FOR
TRANSFER TAX STAMPS TO BE AFFIXED TO THE OLD NOTES SPECIFIED IN THIS LETTER.

7.  WAIVER OF CONDITIONS.

    The Company reserves the absolute right to waive satisfaction of any or all
conditions enumerated in the Prospectus.

8.  NO CONDITIONAL TENDERS.

    No alternative, conditional, irregular or contingent tenders will be
accepted. All tendering Holders of Old Notes, by execution of this Letter, shall
waive any right to receive notice of the acceptance of their Old Notes for
exchange.

    Neither the Company, the Exchange Agent nor any other person is obligated to
give notice of any defect or irregularity with respect to any tender of Old
Notes nor shall any of them incur any liability for failure to give any such
notice.
<PAGE>
9.  MUTILATED, LOST, STOLEN OR DESTROYED OLD NOTES.

    Any Holder whose Old Notes have been mutilated, lost, stolen or destroyed
should contact the Exchange Agent at the address indicated above for further
instructions.

10. WITHDRAWAL RIGHTS.

    Tenders of Old Notes of a series may be withdrawn at any time prior to 5:00
P.M., New York City time, on the Expiration Date with respect to such series.

    For a withdrawal of a tender of Old Notes to be effective, a written notice
of withdrawal must be received by the Exchange Agent at the address set forth
above prior to 5:00 P.M., New York City time, on the Expiration Date with
respect to such series. Any such notice of withdrawal must (i) specify the name
of the person having tendered the Old Notes to be withdrawn (the "Depositor"),
(ii) identify the Old Notes to be withdrawn (including the principal amount of
such Old Notes), (iii) in the case of Old Notes tendered by book-entry transfer,
specify the number of the account at the Book-Entry Transfer Facility from which
the Old Notes were tendered and specify the name and number of the account at
the Book-Entry Transfer Facility to be credited with the withdrawn Old Notes and
otherwise comply with the procedures of such facility, (iv) contain a statement
that such Holder is withdrawing its election to have such Old Notes exchanged,
(v) be signed by the Holder in the same manner as the original signature on the
Letter by which such Old Notes were tendered (including any required signature
guarantees) or be accompanied by documents of transfer to have the Trustee with
respect to the Old Notes register the transfer of such Old Notes in the name of
the person withdrawing the tender and (vi) specify the name in which such Old
Notes are registered, if different from that of the Depositor. All questions as
to the validity, form and eligibility (including time of receipt) of such
notices will be determined by the Company, whose determination shall be final
and binding on all parties. Any Old Notes so withdrawn will be deemed not to
have been validly tendered for exchange for purposes of the Exchange Offer and
no New Notes will be issued with respect thereto unless the Old Notes so
withdrawn are validly retendered. Any Old Notes that have been tendered for
exchange but which are not exchanged for any reason will be returned to the
tendering Holder thereof without cost to such Holder (or, in the case of Old
Notes tendered by book-entry transfer into the Exchange Agent's account at the
Book-Entry Transfer Facility pursuant to the book-entry transfer procedures set
forth in "The Exchange Offer--Book-Entry Transfer" section of the Prospectus,
such Old Notes will be credited to an account maintained with the Book-Entry
Transfer Facility for the Old Notes) as soon as practicable after withdrawal,
rejection of tender or termination of the Exchange Offer. Properly withdrawn Old
Notes may be retendered by following the procedures described above at any time
on or prior to 5:00 P.M., New York City time, on the Expiration Date with
respect to such series of Old Notes.

11. REQUESTS FOR ASSISTANCE OR ADDITIONAL COPIES.

    Questions relating to the procedure for tendering, as well as requests for
additional copies of the Prospectus and this Letter, and requests for Notices of
Guaranteed Delivery and other related documents may be directed to the Exchange
Agent, at the address and telephone number indicated above.
<PAGE>
                    TO BE COMPLETED BY ALL TENDERING HOLDERS
                              (SEE INSTRUCTION 5)

            PAYOR'S NAME: THE CHASE MANHATTAN BANK, AS PAYING AGENT

<TABLE>
<C>                               <S>                  <C>
- ---------------------------------------------------------------------------------------
           SUBSTITUTE             PART 1--PLEASE
                                  PROVIDE
                                  YOUR TIN IN THE BOX
                                  AT RIGHT AND
                                  CERTIFY
                                  BY SIGNING AND
                                  DATING BELOW.

                                  -----------------------------------------------------

                                                       TIN:
                                                          SOCIAL SECURITY NUMBER OR
                                                        EMPLOYER IDENTIFICATION NUMBER
            Form W-9              PART 2--TIN APPLIED FOR / /
                                  -----------------------------------------------------

                                  CERTIFICATION: UNDER THE PENALTIES OF PERJURY,
                                  I CERTIFY THAT:
                                  (1) the number shown on this form is my correct
                                  Taxpayer Identification Number (or I am waiting for a
                                      number to be issued to me).
                                  (2) I am not subject to backup withholding either
                                  because: (a) I am exempt from backup withholding, or
                                      (b) I have not been notified by the Internal
                                      Revenue Service (the "IRS") that I am subject to
                                      backup withholding as a result of a failure to
                                      report all interest or dividends, or (c) the IRS
                                      has notified me that I am no longer subject to
   DEPARTMENT OF THE TREASURY
    INTERNAL REVENUE SERVICE
  PAYOR'S REQUEST FOR TAXPAYER
     IDENTIFICATION NUMBER            backup withholding, and
   ("TIN") AND CERTIFICATION      (3) any other information provided on this form is
                                  true and correct.
                                  Signature
                                  --------------------------------------- Date
                                  ------------

- ---------------------------------------------------------------------------------------
 You must cross out item (2) of the above certification if you have be notified by the
 IRS that you are subject to backup withholding because of underreporting of interest
 or dividends on your tax return and you have not been notified by the IRS that you are
 no longer subject to backup withholding.

 --------------------------------------------------------------------------------------
</TABLE>

       YOU MUST COMPLETE THE FOLLOWING CERTIFICATE IF YOU CHECKED THE BOX
                        IN PART 2 OF SUBSTITUTE FORM W-9

<TABLE>
<C>                               <S>                  <C>
- ---------------------------------------------------------------------------------------

                CERTIFICATE OF AWAITING TAXPAYER IDENTIFICATION NUMBER

 I certify under penalties of perjury that a taxpayer identification number has not
 been issued to me, and either (a) I have mailed or delivered an application to receive
 a taxpayer identification number to the appropriate Internal Revenue Service Center or
 Social Security Administration Office or (b) I intend to mail or deliver an
 application in the near future. I understand that if I do not provide a taxpayer
 identification number by the time of the exchange, 31 percent of all reportable
 payments made to me thereafter will be withheld until I provide a number.

 Signature ----------------------------------------------------- Date
 --------------------
- ---------------------------------------------------------------------------------------
</TABLE>

NOTE: FAILURE TO COMPLETE THIS FORM MAY RESULT IN BACKUP WITHHOLDING OF 31% OF
      ANY PAYMENTS MADE TO YOU PURSUANT TO THE TENDER OFFER AND/OR THE
      SOLICITATION. PLEASE REVIEW THE ENCLOSED GUIDELINES FOR CERTIFICATION OF
<PAGE>
      TAXPAYER IDENTIFICATION NUMBER ON SUBSTITUTE FORM W-9 FOR ADDITIONAL
      DETAILS.

<PAGE>
                                                                    EXHIBIT 99.2

                             LETTER OF TRANSMITTAL
                          CARRIER1 INTERNATIONAL S.A.

                         Offer to Exchange all Outstanding
               13 1/4% Senior Euro Notes Due 2009 (Non-DTC Held)
                                      for
               13 1/4% Senior Euro Notes Due 2009 (Non-DTC Held)
                        which Have Been Registered Under
                           the Securities Act of 1933
              Pursuant to the Prospectus, dated             , 1999

- --------------------------------------------------------------------------------
    THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY TIME, ON
          , 1999 UNLESS EXTENDED (THE "EXPIRATION DATE"). TENDERS MAY BE
   WITHDRAWN PRIOR TO 5:00 P.M., NEW YORK CITY TIME, ON THE EXPIRATION DATE.
- --------------------------------------------------------------------------------

             DELIVERY TO: The Chase Manhattan Bank, EXCHANGE AGENT

<TABLE>
<S>                                            <C>
          BY MAIL, HAND DELIVERY OR                        FOR INFORMATION CALL:
             OVERNIGHT CARRIER:                              (44-171) 777-5414

          The Chase Manhattan Bank                    FACSIMILE TRANSMISSION NUMBER:
     Capital Markets Fiduciary Services                      (44-171) 777-5410
            9 Thomas Moore Street
                London E19YT                               CONFIRM BY TELEPHONE:
               United Kingdom                                (44-171) 777-5414
           Attention: Chris Greene
</TABLE>

DELIVERY OF THIS LETTER OF TRANSMITTAL TO AN ADDRESS OTHER THAN AS SET FORTH
     ABOVE, OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE OTHER THAN AS
             SET FORTH ABOVE, WILL NOT CONSTITUTE A VALID DELIVERY.

                 PLEASE READ THIS ENTIRE LETTER OF TRANSMITTAL
                   CAREFULLY BEFORE COMPLETING ANY BOX BELOW
<PAGE>
    The undersigned acknowledges that he, she or it has received and reviewed
this Letter of Transmittal (the "Letter") and the Prospectus, dated         ,
1999 (the "Prospectus"), of Carrier1 International S.A., a societe anonyme
organized under the laws of the Grand Duchy of Luxembourg (the "Company" or the
"Issuer"), relating to its offer to exchange (i) up to $160,000,000 aggregate
principal amount of its 13 1/4% Senior Dollar Notes Due 2009 (the "New Dollar
Notes"), which have been registered under the Securities Act of 1933, as amended
(the "Securities Act"), for a like principal amount of its issued and
outstanding 13 1/4% Senior Dollar Notes Due 2009 (the "Old Dollar Notes") from
the registered holders thereof (the "Dollar Note Holders") and (ii) its 13 1/4%
Senior Euro Notes Due 2009 (the "New Euro Notes"), which have been registered
under the Securities Act, for a like principal amount of its issued and
outstanding 13 1/4% Senior Euro Notes Due 2009 (the "Old Euro Notes"). The
Prospectus and this Letter together constitute the Company's offer to exchange
(the "Exchange Offer") its New Euro Notes (except those which are to be
deposited with a custodian for, and registered in the name of, The Depository
Trust Company) (the "New Notes") for a like principal amount of Old Euro Notes
(except those which have been deposited with a custodian for, and registered in
the name of, The Depository Trust Company) (the "Old Notes") from the registered
holders thereof (the "Holders").

    For each Old Note accepted for exchange, the Holder of such Old Note will
receive a New Note having a principal amount equal to that of the surrendered
Old Note. The New Notes will bear interest from the most recent date to which
interest has been paid on the Old Notes or, if no interest has been paid on the
Old Notes, from February 19, 1999. Accordingly, registered Holders of New Notes
on the relevant record date for the first interest payment date following the
consummation of the Exchange Offer will receive interest accruing from the most
recent date to which interest has been paid or, if no interest has been paid,
from February 19, 1999. Old Notes accepted for exchange will cease to accrue
interest from and after the date of consummation of the Exchange Offer. Holders
of Old Notes whose Old Notes are accepted for exchange will not receive any
payment in respect of accrued interest on such Old Notes otherwise payable on
any interest payment date the record date for which occurs on or after
consummation of the Exchange Offer.

    This Letter is to be completed by a Holder of Old Notes either if
certificates are to be forwarded herewith or if a tender of certificates for Old
Notes, if available, is to be made by book-entry transfer to the account
maintained by the Exchange Agent at Euroclear and Cedel Bank (the "Book-Entry
Transfer Facility") pursuant to the procedures set forth in "The Exchange
Offer--Book-Entry Transfer" section of the Prospectus. Holders of Old Notes
whose certificates are not immediately available, or who are unable to deliver
their certificates or confirmation of the book-entry tender of their Old Notes
into the Exchange Agent's account at the Book-Entry Transfer Facility (a
"Book-Entry Confirmation") and all other documents required by this Letter to
the Exchange Agent on or prior to the Expiration Date, must tender their Old
Notes according to the guaranteed delivery procedures set forth in "The Exchange
Offer-- Guaranteed Delivery Procedures" section of the Prospectus. See
Instruction 1. Delivery of documents to the Book-Entry Transfer Facility does
not constitute delivery to the Exchange Agent.

    List below the Old Notes to which this Letter relates. If the space provided
below is inadequate, the certificate numbers and principal amount of Old Notes
should be listed on a separate signed schedule affixed hereto.

<TABLE>
<CAPTION>
- -----------------------------------------------------------------------------------------------------
                                      DESCRIPTION OF OLD NOTES
- -----------------------------------------------------------------------------------------------------
                                                          (1)              (2)              (3)
                                                                        AGGREGATE
             NAME(S) AND ADDRESS(ES)                                    PRINCIPAL        PRINCIPAL
             OF REGISTERED HOLDER(S)                  CERTIFICATE       AMOUNT OF         AMOUNT
            (PLEASE FILL IN, IF BLANK)                NUMBER(S)*       OLD NOTE(S)      TENDERED**
<S>                                                 <C>              <C>              <C>
- -----------------------------------------------------------------------------------------------------

                                                    -------------------------------------------------

                                                    -------------------------------------------------

                                                    -------------------------------------------------
                                                         TOTAL
- -----------------------------------------------------------------------------------------------------
</TABLE>

*   Need not be completed if Old Notes are being tendered by book-entry
    transfer.
<PAGE>
**  Unless otherwise indicated in this column, a holder will be deemed to have
    tendered ALL of the Old Notes represented by the Old Notes indicated in
    column 2. See Instruction 2. Old Notes tendered hereby must be in
    denominations of principal amount of $1,000 and any integral multiple
    thereof. See Instruction 1.

/ /  CHECK HERE IF TENDERED OLD NOTES ARE BEING DELIVERED BY BOOK-ENTRY TRANSFER
    MADE TO THE ACCOUNT MAINTAINED BY THE EXCHANGE AGENT WITH THE BOOK-ENTRY
    TRANSFER FACILITY AND COMPLETE THE FOLLOWING:

    Name of Tendering Institution ______________________________________________
    Account Number _____________________________________________________________
    Transaction Code Number ____________________________________________________
/ /  CHECK HERE IF TENDERED OLD NOTES ARE BEING DELIVERED PURSUANT TO A NOTICE
    OF GUARANTEED DELIVERY PREVIOUSLY SENT TO THE EXCHANGE AGENT AND COMPLETE
    THE FOLLOWING:

    Name(s) of Registered Holder(s) ____________________________________________
    Window Ticket Number (if any) ______________________________________________
    Date of Execution of Notice of Guaranteed Delivery _________________________
    Name of Institution Which Guaranteed Delivery ______________________________
    IF DELIVERED BY BOOK-ENTRY TRANSFER, COMPLETE THE FOLLOWING:

    Account Number _____________________________________________________________
    Transaction Code Number ____________________________________________________
/ /  CHECK HERE IF YOU ARE A BROKER-DEALER ENTITLED, PURSUANT TO THE TERMS OF
    THE REGISTRATION RIGHTS AGREEMENT REFERRED TO IN THE PROSPECTUS, TO RECEIVE,
    AND WISH TO RECEIVE, 10 ADDITIONAL COPIES OF THE PROSPECTUS AND 10 COPIES OF
    ANY AMENDMENTS OR SUPPLEMENTS THERETO WITHIN 90 DAYS AFTER THE EXPIRATION
    DATE.

    Name: ______________________________________________________________________
    Address: ___________________________________________________________________

    If the undersigned is not a broker-dealer, the undersigned represents that
it is not engaged in, and does not intend to engage in, a distribution of New
Notes. If the undersigned is a broker-dealer that will receive New Notes for its
own account in exchange for Old Notes that were acquired as a result of
market-making activities or other trading activities, it acknowledges and
represents that it will deliver a prospectus meeting the requirements of the
Securities Act, in connection with any resale of such New Notes; however, by so
acknowledging and representing and by delivering such a prospectus the
undersigned will not be deemed to admit that it is an "underwriter" within the
meaning of the Securities Act. If the undersigned is a broker-dealer that will
receive New Notes, it represents that the Old Notes to be exchanged for the New
Notes were acquired as a result of market-making activities or other trading
activities. In addition, such broker-dealer represents that it is not acting on
behalf of any person who could not truthfully make the foregoing
representations.
<PAGE>
              PLEASE READ THE ACCOMPANYING INSTRUCTIONS CAREFULLY

    Ladies and Gentlemen:

    Upon the terms and subject to the conditions of the Exchange Offer, the
undersigned hereby tenders to the Company the aggregate principal amount of Old
Notes indicated above. Subject to, and effective upon, the acceptance for
exchange of the Old Notes tendered hereby, the undersigned hereby sells, assigns
and transfers to, or upon the order of, the Company all right, title and
interest in and to such Old Notes as are being tendered hereby.

    The undersigned hereby irrevocably constitutes and appoints the Exchange
Agent as the undersigned's true and lawful agent and attorney-in-fact with
respect to such tendered Old Notes, with full power of substitution, among other
things, to cause the Old Notes to be assigned, transferred and exchanged. The
undersigned hereby represents and warrants that the undersigned has full power
and authority to tender, sell, assign and transfer the Old Notes, and to acquire
New Notes issuable upon the exchange of such tendered Old Notes, and that, when
such Old Notes are accepted for exchange, the Company will acquire good and
unencumbered title thereto, free and clear of all liens, restrictions, charges
and encumbrances and not subject to any adverse claim when the same are accepted
by the Company. The undersigned hereby further represents and warrants that any
New Notes acquired in exchange for Old Notes tendered hereby will have been
acquired in the ordinary course of business of the person receiving such New
Notes, whether or not such person is the undersigned, that neither the Holder of
such Old Notes nor any such other person is participating in, intends to
participate in or has an arrangement or understanding with any person to
participate in the distribution (within the meaning of the Securities Act) of
Old Notes or New Notes, that neither the Holder of such Old Notes nor any such
other person is an "affiliate," as defined in Rule 405 under the Securities Act,
of the Company, and that neither the Holder of such Old Notes nor such other
person is acting on behalf of any person who could not truthfully make the
foregoing representations and warranties.

    The undersigned acknowledges that this Exchange Offer is being made in
reliance on interpretations by the staff of the Securities and Exchange
Commission (the "SEC"), as set forth in no-action letters issued to third
parties, that the New Notes issued pursuant to the Exchange Offer in exchange
for the Old Notes may be offered for resale, resold and otherwise transferred by
Holders thereof (other than any such Holder that is a broker-dealer or an
"affiliate" of the Company within the meaning of Rule 405 under the Securities
Act), without compliance with the registration and prospectus delivery
provisions of the Securities Act, provided that such New Notes are acquired in
the ordinary course of such Holder's business, at the time of commencement of
the Exchange Offer such Holder has no arrangement or understanding with any
person to participate in a distribution of such New Notes, and such Holder is
not engaged in, and does not intend to engage in, a distribution of such New
Notes. However, the SEC has not considered the Exchange Offer in the context of
a no-action letter and there can be no assurance that the staff of the SEC would
make a similar determination with respect to the Exchange Offer as in other
circumstances. If the undersigned is not a broker-dealer, the undersigned
represents that it is not engaged in, and does not intend to engage in, a
distribution of New Notes and has no arrangement or understanding to participate
in a distribution of New Notes. If the undersigned is a broker-dealer that will
receive New Notes for its own account in exchange for Old Notes, it represents
that the Old Notes to be exchanged for the New Notes were acquired by it as a
result of market-making activities or other trading activities and acknowledges
that it will deliver a prospectus meeting the requirements of the Securities Act
in connection with any resale of such New Notes; however, by so acknowledging
and by delivering a prospectus meeting the requirements of the Securities Act,
the undersigned will not be deemed to admit that it is an "underwriter" within
the meaning of the Securities Act.

    The SEC has taken the position that such broker-dealers may fulfill their
prospectus delivery requirements with respect to the New Notes (other than a
resale of New Notes received in exchange for an unsold allotment from the
original sale of the Old Notes) with the Prospectus. The Prospectus, as it may
be amended or supplemented from time to time, may be used by certain
broker-dealers (as specified in the Registration Rights Agreement referenced in
the Prospectus) ("Participating Broker-Dealers") for a period of time, starting
on the Expiration Date and ending on the close of business 90 days after the
<PAGE>
Expiration Date in connection with the sale or transfer of such New Notes. The
Company has agreed that, for such period of time, it will make the Prospectus
(as it may be amended or supplemented) available to such a broker-dealer which
elects to exchange Old Notes, acquired for its own account as a result of market
making or other trading activities, for New Notes pursuant to the Exchange Offer
for use in connection with any resale of such New Notes. By accepting the
Exchange Offer, each broker-dealer that receives New Notes pursuant to the
Exchange Offer acknowledges and agrees to notify the Company prior to using the
Prospectus in connection with the sale or transfer of New Notes and that, upon
receipt of notice from the Company of the happening of any event which makes any
statement in the Prospectus untrue in any material respect or which requires the
making of any changes in the Prospectus in order to make the statements therein
(in light of the circumstances under which they were made) not misleading, such
broker-dealer will suspend use of the Prospectus until (i) the Company has
amended or supplemented the Prospectus to correct such misstatement or omission
and (ii) either the Company has furnished copies of the amended or supplemented
Prospectus to such broker-dealer or, if the Company has not otherwise agreed to
furnish such copies and declines to do so after such broker-dealer so requests,
such broker-dealer has obtained a copy of such amended or supplemented
Prospectus as filed with the SEC. Except as described above, the Prospectus may
not be used for or in connection with an offer to resell, a resale or any other
retransfer of New Notes. A broker-dealer that acquired Old Notes in a
transaction other than as part of its market-making activities or other trading
activities will not be able to participate in the Exchange Offer.

    The undersigned will, upon request, execute and deliver any additional
documents deemed by the Company to be necessary or desirable to complete the
sale, assignment and transfer of the Old Notes tendered hereby. All authority
conferred or agreed to be conferred in this Letter and every obligation of the
undersigned hereunder shall be binding upon the successors, assigns, heirs,
executors, administrators, trustees in bankruptcy and legal representatives of
the undersigned and shall not be affected by, and shall survive, the death or
incapacity of the undersigned. This tender may be withdrawn only in accordance
with the procedures set forth in "The Exchange Offer--Withdrawal of Tenders"
section of the Prospectus.

    Unless otherwise indicated herein in the box entitled "Special Issuance
Instructions" below, please deliver the New Notes (and, if applicable,
substitute certificates representing Old Notes for any Old Notes not exchanged)
in the name of the undersigned or, in the case of a book-entry delivery of Old
Notes, please credit the account indicated above maintained at the Book-Entry
Transfer Facility. Similarly, unless otherwise indicated under the box entitled
"Special Delivery Instructions" below, please send the New Notes (and, if
applicable, substitute certificates representing Old Notes for any Old Notes not
exchanged) to the undersigned at the address shown above in the box entitled
"Description of Old Notes."

    THE UNDERSIGNED, BY COMPLETING THE BOX ENTITLED "DESCRIPTION OF OLD NOTES"
ABOVE AND SIGNING THIS LETTER, WILL BE DEEMED TO HAVE TENDERED THE OLD NOTES AS
SET FORTH IN SUCH BOX ABOVE.

                 PLEASE READ THIS ENTIRE LETTER OF TRANSMITTAL
                   CAREFULLY BEFORE COMPLETING ANY BOX ABOVE.
<PAGE>
- --------------------------------------------------------------------------------

                                PLEASE SIGN HERE
                   (TO BE COMPLETED BY ALL TENDERING HOLDERS)

  x ___________________________________________________________________ , 1999

  x ___________________________________________________________________ , 1999

  ____________________________________________________________________________
             Signature(s) of Owner                              Date

  Area Code and Telephone Number _____________________________________________

      If a Holder is tendering an Old Note, this Letter must be signed by the
  registered Holder(s) as the name(s) appear(s) on the certificate(s) for the
  Old Note or by any person(s) authorized to become registered Holder(s) by
  endorsements and documents transmitted herewith. If signature is by a
  trustee, executor, administrator, guardian, officer or other person acting
  in a fiduciary or representative capacity, please set forth full title. See
  Instruction 3.

  Name(s) ____________________________________________________________________
  ____________________________________________________________________________
                             (PLEASE TYPE OR PRINT)

  Capacity: __________________________________________________________________

  Address: ___________________________________________________________________
  ____________________________________________________________________________
  ____________________________________________________________________________
  ____________________________________________________________________________

                              SIGNATURE GUARANTEE
                         (IF REQUIRED BY INSTRUCTION 3)

  SIGNATURE(S) GUARANTEED BY _________________________________________________

  AN ELIGIBLE INSTITUTION: ___________________________________________________
                             (AUTHORIZED SIGNATURE)

   __________________________________________________________________________
                                    (TITLE)

   __________________________________________________________________________
                                (NAME AND FIRM)

  DATED: ______________________________________________________________ , 1999

   (PLEASE COMPLETE ACCOMPANYING SUBSTITUTE FORM W-9 HEREIN. SEE INSTRUCTION
                                      5.)

- --------------------------------------------------------------------------------
<PAGE>
- -------------------------------------------

                         SPECIAL ISSUANCE INSTRUCTIONS
                         (SEE INSTRUCTIONS 3, 4 AND 6)

      To be completed ONLY if certificates for Old Notes not exchanged and/or
  New Notes are to be issued in the name of and sent to someone other than the
  person or persons whose signature(s) appear(s) on this Letter above, or if
  Old Notes delivered by book-entry transfer which are not accepted for
  exchange are to be returned by credit to an account maintained at the
  Book-Entry Transfer Facility other than the account indicated above.

  Issue: New Notes and/or Old Notes to:
  Name(s) ____________________________________________________________________
                             (PLEASE TYPE OR PRINT)
    _________________________________________________________________________
                             (PLEASE TYPE OR PRINT)

  Address ____________________________________________________________________

  ____________________________________________________________________________

  ____________________________________________________________________________
                                   (ZIP CODE)

   __________________________________________________________________________
                         (COMPLETE SUBSTITUTE FORM W-9)

  / / Credit unexchanged Old Notes delivered by book-entry transfer to the
      Book-Entry Transfer Facility account set forth below.

      ________________________________________________________________________
                           (BOOK-ENTRY TRANSFER FACILITY
                          ACCOUNT NUMBER, IF APPLICABLE)

- ------------------------------------------------------
- ------------------------------------------------------

                         SPECIAL DELIVERY INSTRUCTIONS
                         (SEE INSTRUCTIONS 3, 4 AND 6)

      To be completed ONLY if certificates for Old Notes not exchanged and/or
  New Notes are to be sent to someone other than the person or persons whose
  signature(s) appear(s) on this Letter above or to such person or persons at
  an address other than shown in the box entitled "Description of Old Notes"
  on this Letter above.

  Mail: New Notes and/or Old Notes to:

  Name(s) ____________________________________________________________________
                             (PLEASE TYPE OR PRINT)

    _________________________________________________________________________
                             (PLEASE TYPE OR PRINT)

  Address ____________________________________________________________________

  ____________________________________________________________________________

  ____________________________________________________________________________
                                   (ZIP CODE)

- -----------------------------------------------------

IMPORTANT: UNLESS GUARANTEED DELIVERY PROCEDURES ARE COMPLIED WITH, THIS LETTER
OR A FACSIMILE HEREOF (TOGETHER WITH THE CERTIFICATES FOR OLD NOTES OR A
BOOK-ENTRY CONFIRMATION AND ALL OTHER REQUIRED DOCUMENTS) MUST BE RECEIVED BY
THE EXCHANGE AGENT PRIOR TO 5:00 P.M., NEW YORK CITY TIME, ON THE EXPIRATION
DATE.
<PAGE>
                                  INSTRUCTIONS
     FORMING PART OF THE TERMS AND CONDITIONS OF THE EXCHANGE OFFER FOR THE
               13 1/4% SENIOR EURO NOTES DUE 2009 (NON-DTC HELD)
               OF CARRIER1 INTERNATIONAL S.A. IN EXCHANGE FOR THE
               13 1/4% SENIOR EURO NOTES DUE 2009 (NON-DTC HELD)
      OF CARRIER1 INTERNATIONAL S.A., WHICH HAVE BEEN REGISTERED UNDER THE
                       SECURITIES ACT OF 1933, AS AMENDED

1.  DELIVERY OF THIS LETTER AND NOTES; GUARANTEED DELIVERY PROCEDURES.

    This Letter is to be completed by Holders of Old Notes either if
certificates are to be forwarded herewith or if tenders are to be made pursuant
to the procedures for delivery by book-entry transfer set forth in "The Exchange
Offer--Book-Entry Transfer" section of the Prospectus. Certificates for all
physically tendered Old Notes, or Book-Entry Confirmation, as the case may be,
as well as a properly completed and duly executed Letter (or manually signed
facsimile hereof) and any other documents required by this Letter, must be
received by the Exchange Agent at the address set forth herein on or prior to
the Expiration Date, or the tendering Holder must comply with the guaranteed
delivery procedures set forth below. Old Notes tendered hereby must be in
denominations of principal amount of [EURO]1,000 and any integral multiple
thereof.

    Holders whose certificates for Old Notes are not immediately available or
who cannot deliver their certificates and all other required documents to the
Exchange Agent on or prior to the Expiration Date, or who cannot complete the
procedure for book entry transfer on a timely basis, may tender their Old Notes
pursuant to the guaranteed delivery procedures set forth in "The Exchange
Offer--Guaranteed Delivery Procedures" section of the Prospectus. Pursuant to
such procedures, (i) such tender must be made through an Eligible Institution,
(ii) prior to 5:00 P.M., New York City time, on the Expiration Date, the
Exchange Agent must receive from such Eligible Institution a properly completed
and duly executed Letter (or a facsimile thereof) and Notice of Guaranteed
Delivery, substantially in the form provided by the Company (by facsimile
transmission, mail or hand delivery), setting forth the name and address of the
Holder of Old Notes and the amount of Old Notes tendered, stating that the
tender is being made thereby and guaranteeing that within three New York Stock
Exchange ("NYSE") trading days after the date of execution of the Notice of
Guaranteed Delivery, the certificates for all physically-tendered Old Notes, in
proper form for transfer, or a Book-Entry Confirmation, as the case may be, and
any other documents required by this Letter will be deposited by the Eligible
Institution with the Exchange Agent, and (iii) the certificates for all
physically-tendered Old Notes, in proper form for transfer, or a Book-Entry
Confirmation, as the case may be, and all other documents required by this
Letter, are received by the Exchange Agent within three NYSE trading days after
the date of execution of the Notice of Guaranteed Delivery.

    The method of delivery of this Letter, the Old Notes and all other required
documents is at the election and risk of the tendering Holders, but the delivery
will be deemed made only when actually received or confirmed by the Exchange
Agent. If Old Notes are sent by mail, it is suggested that the mailing be
registered mail, properly insured, with return receipt requested, made
sufficiently in advance of the Expiration Date to permit delivery to the
Exchange Agent prior to 5:00 P.M., New York City time, on the Expiration Date.

    See "The Exchange Offer" section of the Prospectus.

2.  PARTIAL TENDERS (NOT APPLICABLE TO NOTEHOLDERS WHO TENDER BY BOOK-ENTRY
    TRANSFER).

    If less than all of the Old Notes evidenced by a submitted certificate are
to be tendered, the tendering Holder(s) should fill in the aggregate principal
amount of Old Notes to be tendered in the box above entitled "Description of Old
Notes--Principal Amount Tendered." A reissued certificate representing the
balance of nontendered Old Notes will be sent to such tendering Holder, unless
otherwise provided in the appropriate box on this Letter, promptly after the
Expiration Date. ALL OF THE OLD NOTES DELIVERED TO THE EXCHANGE AGENT WILL BE
DEEMED TO HAVE BEEN TENDERED UNLESS OTHERWISE INDICATED.
<PAGE>
3.  SIGNATURES ON THIS LETTER; BOND POWERS AND ENDORSEMENTS; GUARANTEE OF
    SIGNATURES.

    If this Letter is signed by the registered Holder of the Old Notes tendered
hereby, the signature must correspond exactly with the name as written on the
face of the certificates without any change whatsoever.

    If any tendered Old Notes are owned of record by two or more joint owners,
all of such owners must sign this Letter.

    If any tendered Old Notes are registered in different names on several
certificates, it will be necessary to complete, sign and submit as many separate
copies of this Letter as there are different registrations of certificates.

    When this Letter is signed by the registered Holder or Holders of the Old
Notes specified herein and tendered hereby, no endorsements of certificates or
separate bond powers are required. If, however, the New Notes are to be issued,
or any untendered Old Notes are to be reissued, to a person other than the
registered Holder, then endorsements of any certificates transmitted hereby or
separate bond powers are required. Signatures on such certificate(s) must be
guaranteed by an Eligible Institution.

    If this Letter is signed by a person other than the registered Holder or
Holders of any certificate(s) specified herein, such certificate(s) must be
endorsed or accompanied by appropriate bond powers, in either case signed
exactly as the name or names of the registered Holder or Holders appear(s) on
the certificate(s) and signatures on such certificate(s) must be guaranteed by
an Eligible Institution.

    If this Letter or any certificates or bond powers are signed by trustees,
executors, administrators, guardians, attorneys-in-fact, officers of
corporations or others acting in a fiduciary or representative capacity, such
persons should so indicate when signing, and, unless waived by the Company,
proper evidence satisfactory to the Company of their authority to so act must be
submitted.

    ENDORSEMENTS ON CERTIFICATES FOR OLD NOTES OR SIGNATURES ON BOND POWERS
REQUIRED BY THIS INSTRUCTION 3 MUST BE GUARANTEED BY ANY MEMBER FIRM OF A
REGISTERED NATIONAL SECURITIES EXCHANGE OR OF THE NATIONAL ASSOCIATION OF
SECURITIES DEALERS, INC., A COMMERCIAL BANK OR TRUST COMPANY HAVING AN OFFICE OR
CORRESPONDENT IN THE UNITED STATES OR AN "ELIGIBLE GUARANTOR INSTITUTION" WITHIN
THE MEANING OF RULE 17AD-15 UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS
AMENDED (EACH AN "ELIGIBLE INSTITUTION").

    SIGNATURES ON THIS LETTER NEED NOT BE GUARANTEED BY AN ELIGIBLE INSTITUTION,
PROVIDED THE OLD NOTES ARE TENDERED: (I) BY A REGISTERED HOLDER OF OLD NOTES
(WHICH TERM, FOR PURPOSES OF THE EXCHANGE OFFER, INCLUDES ANY PARTICIPANT IN THE
BOOK-ENTRY TRANSFER FACILITY SYSTEM WHOSE NAME APPEARS ON A SECURITY POSITION
LISTING AS THE HOLDER OF SUCH OLD NOTES) WHO HAS NOT COMPLETED THE BOX ENTITLED
"SPECIAL ISSUANCE INSTRUCTIONS" OR "SPECIAL DELIVERY INSTRUCTIONS" IN THIS
LETTER, OR (II) FOR THE ACCOUNT OF AN ELIGIBLE INSTITUTION.

4.  SPECIAL ISSUANCE AND DELIVERY INSTRUCTIONS.

    Tendering Holders of Old Notes should indicate in the applicable box the
name and address to which New Notes issued pursuant to the Exchange Offer and or
substitute certificates evidencing Old Notes not exchanged are to be issued or
sent, if different from the name or address of the person signing this Letter.
In the case of issuance in a different name, the employer identification or
social security number of the person named must also be indicated. Holders
tendering Old Notes by book-entry transfer may request that Old Notes not
exchanged be credited to such account maintained at the Book-Entry Transfer
Facility as such Holder may designate hereon. If no such instructions are given,
such Old Notes not exchanged will be returned to the name and address of the
person signing this Letter.

5.  TAXPAYER IDENTIFICATION NUMBER.

    Federal income tax law generally requires that a tendering Holder whose Old
Notes are accepted for exchange must provide the Company (as payor), or the
Paying Agent designated by the Company to act on its behalf, with such Holder's
correct Taxpayer Identification Number ("TIN") on Substitute Form W-9 below,
which in the case of a tendering Holder who is an individual, is his or her
social security number. If the Company is not provided with the current TIN or
an adequate basis for an exemption from backup
<PAGE>
withholding, such tendering Holder may be subject to a $50 penalty imposed by
the Internal Revenue Service. In addition, delivery to such tendering Holder of
New Notes may result in backup withholding in an amount equal to 31% of all
reportable payments made after the exchange. If withholding results in an
overpayment of taxes, a refund may be obtained.

    Exempt Holders of Old Notes (including, among others, all corporations and
certain foreign individual) are not subject to these backup withholding and
reporting requirements. See the enclosed Guidelines of Certification of Taxpayer
Identification Number on Substitute Form W-9 (the "W-9 Guidelines") for
additional instructions.

    To prevent backup withholding, each tendering Holder of Old Notes must
provide its correct TIN by completing the Substitute Form W-9 set forth below,
certifying, under penalties of perjury, that the TIN provided is correct (or
that such Holder is awaiting a TIN) and that (i) the Holder is exempt from
backup withholding, or (ii) the Holder has not been notified by the Internal
Revenue Service that such Holder is subject to backup withholding as a result of
a failure to report all interest or dividends or (iii) the Internal Revenue
Service has notified the Holder that such Holder is no longer subject to backup
withholding. If the tendering Holder of Old Notes is a nonresident alien or
foreign entity not subject to backup withholding, such Holder must give the
Exchange Agent a completed Form W-8, Certificate of Foreign Status. This form
may be obtained from the Exchange Agent. If the Old Notes are in more than one
name or are not in the name of the actual owner, such Holder should consult the
W-9 Guidelines for information on which TIN to report. If such Holder does not
have a TIN, such Holder should consult the W-9 Guidelines for instructions on
applying for a TIN, check the box in Part 2 of the Substitute Form W-9 and write
"applied for" in lieu of its TIN. Note: Checking this box and writing "applied
for" on the form means that such Holder has already applied for a TIN or that
such Holder intends to apply for one in the near future. If such Holder does not
provide its TIN to the Issuer within 60 days, backup withholding will begin and
continue until such Holder furnishes its TIN to the Issuer.

6.  TRANSFER TAXES.

    The Company will pay all transfer taxes, if any, applicable to the transfer
of Old Notes to it or its order pursuant to the Exchange Offer. If, however, New
Notes and/or substitute Old Notes not exchanged are to be delivered to, or are
to be registered or issued in the name of, any person other than the registered
Holder of the Old Notes tendered hereby, or if tendered Old Notes are registered
in the name of any person other than the person signing this Letter, or if a
transfer tax is imposed for any reason other than the transfer of Old Notes to
the Company or its order pursuant to the Exchange Offer, the amount of any such
transfer taxes (whether imposed on the registered Holder or any other persons)
will be payable by the tendering Holder. If satisfactory evidence of payment of
such taxes or exemption therefrom is not submitted herewith, the amount of such
transfer taxes will be billed directly to such tendering Holder.

    EXCEPT AS PROVIDED IN THIS INSTRUCTION 6, IT WILL NOT BE NECESSARY FOR
TRANSFER TAX STAMPS TO BE AFFIXED TO THE OLD NOTES SPECIFIED IN THIS LETTER.

7.  WAIVER OF CONDITIONS.

    The Company reserves the absolute right to waive satisfaction of any or all
conditions enumerated in the Prospectus.

8.  NO CONDITIONAL TENDERS.

    No alternative, conditional, irregular or contingent tenders will be
accepted. All tendering Holders of Old Notes, by execution of this Letter, shall
waive any right to receive notice of the acceptance of their Old Notes for
exchange.

    Neither the Company, the Exchange Agent nor any other person is obligated to
give notice of any defect or irregularity with respect to any tender of Old
Notes nor shall any of them incur any liability for failure to give any such
notice.
<PAGE>
9.  MUTILATED, LOST, STOLEN OR DESTROYED OLD NOTES.

    Any Holder whose Old Notes have been mutilated, lost, stolen or destroyed
should contact the Exchange Agent at the address indicated above for further
instructions.

10. WITHDRAWAL RIGHTS.

    Tenders of Old Notes of a series may be withdrawn at any time prior to 5:00
P.M., New York City time, on the Expiration Date with respect to such series.

    For a withdrawal of a tender of Old Notes to be effective, a written notice
of withdrawal must be received by the Exchange Agent at the address set forth
above prior to 5:00 P.M., New York City time, on the Expiration Date with
respect to such series. Any such notice of withdrawal must (i) specify the name
of the person having tendered the Old Notes to be withdrawn (the "Depositor"),
(ii) identify the Old Notes to be withdrawn (including the principal amount of
such Old Notes), (iii) in the case of Old Notes tendered by book-entry transfer,
specify the number of the account at the Book-Entry Transfer Facility from which
the Old Notes were tendered and specify the name and number of the account at
the Book-Entry Transfer Facility to be credited with the withdrawn Old Notes and
otherwise comply with the procedures of such facility, (iv) contain a statement
that such Holder is withdrawing its election to have such Old Notes exchanged,
(v) be signed by the Holder in the same manner as the original signature on the
Letter by which such Old Notes were tendered (including any required signature
guarantees) or be accompanied by documents of transfer to have the Trustee with
respect to the Old Notes register the transfer of such Old Notes in the name of
the person withdrawing the tender and (vi) specify the name in which such Old
Notes are registered, if different from that of the Depositor. All questions as
to the validity, form and eligibility (including time of receipt) of such
notices will be determined by the Company, whose determination shall be final
and binding on all parties. Any Old Notes so withdrawn will be deemed not to
have been validly tendered for exchange for purposes of the Exchange Offer and
no New Notes will be issued with respect thereto unless the Old Notes so
withdrawn are validly retendered. Any Old Notes that have been tendered for
exchange but which are not exchanged for any reason will be returned to the
tendering Holder thereof without cost to such Holder (or, in the case of Old
Notes tendered by book-entry transfer into the Exchange Agent's account at the
Book-Entry Transfer Facility pursuant to the book-entry transfer procedures set
forth in "The Exchange Offer--Book-Entry Transfer" section of the Prospectus,
such Old Notes will be credited to an account maintained with the Book-Entry
Transfer Facility for the Old Notes) as soon as practicable after withdrawal,
rejection of tender or termination of the Exchange Offer. Properly withdrawn Old
Notes may be retendered by following the procedures described above at any time
on or prior to 5:00 P.M., New York City time, on the Expiration Date with
respect to such series of Old Notes.

11. REQUESTS FOR ASSISTANCE OR ADDITIONAL COPIES.

    Questions relating to the procedure for tendering, as well as requests for
additional copies of the Prospectus and this Letter, and requests for Notices of
Guaranteed Delivery and other related documents may be directed to the Exchange
Agent, at the address and telephone number indicated above.
<PAGE>
                    TO BE COMPLETED BY ALL TENDERING HOLDERS
                              (SEE INSTRUCTION 5)

            PAYOR'S NAME: THE CHASE MANHATTAN BANK, AS PAYING AGENT

<TABLE>
<C>                               <S>                  <C>
- ---------------------------------------------------------------------------------------
           SUBSTITUTE             PART 1--PLEASE
                                  PROVIDE
                                  YOUR TIN IN THE BOX
                                  AT RIGHT AND
                                  CERTIFY
                                  BY SIGNING AND
                                  DATING BELOW.

                                  -----------------------------------------------------

                                                       TIN:
                                                          SOCIAL SECURITY NUMBER OR
                                                        EMPLOYER IDENTIFICATION NUMBER
            Form W-9              PART 2--TIN APPLIED FOR / /
                                  -----------------------------------------------------

                                  CERTIFICATION: UNDER THE PENALTIES OF PERJURY,
                                  I CERTIFY THAT:
                                  (1) the number shown on this form is my correct
                                  Taxpayer Identification Number (or I am waiting for a
                                      number to be issued to me).
                                  (2) I am not subject to backup withholding either
                                  because: (a) I am exempt from backup withholding, or
                                      (b) I have not been notified by the Internal
                                      Revenue Service (the "IRS") that I am subject to
                                      backup withholding as a result of a failure to
                                      report all interest or dividends, or (c) the IRS
                                      has notified me that I am no longer subject to
   DEPARTMENT OF THE TREASURY
    INTERNAL REVENUE SERVICE
  PAYOR'S REQUEST FOR TAXPAYER
     IDENTIFICATION NUMBER            backup withholding, and
   ("TIN") AND CERTIFICATION      (3) any other information provided on this form is
                                  true and correct.
                                  Signature
                                  --------------------------------------- Date
                                  ------------

- ---------------------------------------------------------------------------------------
 You must cross out item (2) of the above certification if you have be notified by the
 IRS that you are subject to backup withholding because of underreporting of interest
 or dividends on your tax return and you have not been notified by the IRS that you are
 no longer subject to backup withholding.

 --------------------------------------------------------------------------------------
</TABLE>

       YOU MUST COMPLETE THE FOLLOWING CERTIFICATE IF YOU CHECKED THE BOX
                        IN PART 2 OF SUBSTITUTE FORM W-9

<TABLE>
<C>                               <S>                  <C>
- ---------------------------------------------------------------------------------------

                CERTIFICATE OF AWAITING TAXPAYER IDENTIFICATION NUMBER

 I certify under penalties of perjury that a taxpayer identification number has not
 been issued to me, and either (a) I have mailed or delivered an application to receive
 a taxpayer identification number to the appropriate Internal Revenue Service Center or
 Social Security Administration Office or (b) I intend to mail or deliver an
 application in the near future. I understand that if I do not provide a taxpayer
 identification number by the time of the exchange, 31 percent of all reportable
 payments made to me thereafter will be withheld until I provide a number.

 Signature ----------------------------------------------------- Date
 --------------------
- ---------------------------------------------------------------------------------------
</TABLE>

NOTE: FAILURE TO COMPLETE THIS FORM MAY RESULT IN BACKUP WITHHOLDING OF 31% OF
      ANY PAYMENTS MADE TO YOU PURSUANT TO THE TENDER OFFER AND/OR THE
      SOLICITATION. PLEASE REVIEW THE ENCLOSED GUIDELINES FOR CERTIFICATION OF
<PAGE>
      TAXPAYER IDENTIFICATION NUMBER ON SUBSTITUTE FORM W-9 FOR ADDITIONAL
      DETAILS.

<PAGE>
                                                                    EXHIBIT 99.3

                         NOTICE OF GUARANTEED DELIVERY
                                      FOR
                          CARRIER1 INTERNATIONAL S.A.
                      13 1/4% SENIOR DOLLAR NOTES DUE 2009
                                      AND
                 13 1/4% SENIOR EURO NOTES DUE 2009 (DTC HELD)

    This form or one substantially equivalent hereto must be used to accept the
Exchange Offer of Carrier1, International S.A. (the "Issuer" or the "Company")
made pursuant to the Prospectus, dated         , 1999 (the "Prospectus"), if
certificates (as applicable) for outstanding 13 1/4% Senior Dollar Notes Due
2009 (the "Old Dollar Notes") of the Issuer or for outstanding 13 1/4% Senior
Euro Notes Due 2009 (which have been deposited with a custodian for, and
registered in the name of, The Depository Trust Company ("DTC") or its nominee)
(the "Old DTC Euro Notes" and, together with the Old Dollar Notes, the "Old
Notes") of the Issuer are not immediately available or if the procedure for
book-entry transfer cannot be completed on a timely basis or time will not
permit all required documents to reach The Chase Manhattan Bank, as exchange
agent (the "Exchange Agent") prior to 5:00 P.M., New York City time, on the
Expiration Date of the Exchange Offer. Such form may be delivered or transmitted
by facsimile transmission, mail or hand delivery to the Exchange Agent as set
forth below. In addition, in order to utilize the guaranteed delivery procedure
to tender Old Notes pursuant to the Exchange Offer, a completed, signed and
dated Letter of Transmittal (or facsimile thereof) relating to the tender for
exchange of Old Dollar Notes or Old DTC Euro Notes (the "Letter of Transmittal")
must also be received by the Exchange Agent prior to 5:00 P.M., New York City
time, on the Expiration Date. Capitalized terms not defined herein are defined
in the Prospectus or the Letter of Transmittal.

             DELIVERY TO: The Chase Manhattan Bank, EXCHANGE AGENT

<TABLE>
<S>                                            <C>
          BY MAIL, HAND DELIVERY OR                        FOR INFORMATION CALL:
             OVERNIGHT CARRIER:                               (212) 946-3172

          The Chase Manhattan Bank                    FACSIMILE TRANSMISSION NUMBER:
     Capital Markets Fiduciary Services                      (212) 946-8177/78
            450 West 33rd Street
                 15th Floor                                CONFIRM BY TELEPHONE:
          New York, New York 10001                            (212) 946-3172
          Attention: William Potes
</TABLE>

    DELIVERY OF THIS INSTRUMENT TO AN ADDRESS OTHER THAN AS SET FORTH ABOVE, OR
TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE OTHER THAN AS SET FORTH ABOVE, WILL
NOT CONSTITUTE A VALID DELIVERY.

                PLEASE READ THE ACCOMPANYING INSTRUCTIONS CAREFULLY
<PAGE>
Ladies and Gentlemen:

    Upon the terms and conditions set forth in the Prospectus and the
accompanying Letter of Transmittal, the undersigned hereby tenders to the
Company the principal amount of Old Notes set forth below pursuant to the
guaranteed delivery procedure described in "The Exchange Offer--Guaranteed
Delivery Procedures" section of the Prospectus.

<TABLE>
<CAPTION>
   CERTIFICATE NUMBER(S)
   (IF KNOWN) OF EXISTING
      NOTES OR ACCOUNT                                          AGGREGATE PRINCIPAL
    NUMBER AT THE BOOK-           AGGREGATE PRINCIPAL             AMOUNT TENDERED
  ENTRY TRANSFER FACILITY          AMOUNT REPRESENTED           (IF LESS THAN ALL)*
<S>                           <C>                           <C>
</TABLE>

*   Unless otherwise indicated, the Holder will be deemed to have tendered the
    full aggregate principal amount represented by such Old Notes.

 ALL AUTHORITY HEREIN CONFERRED OR AGREED TO BE CONFERRED SHALL SURVIVE THE
 DEATH OR INCAPACITY OF THE UNDERSIGNED AND EVERY OBLIGATION OF THE UNDERSIGNED
 HEREUNDER SHALL BE BINDING UPON THE HEIRS, PERSONAL REPRESENTATIVES,
 SUCCESSORS AND ASSIGNS OF THE UNDERSIGNED.

                                PLEASE SIGN HERE

<TABLE>
<S>        <C>                                                        <C>
X
           ---------------------------------------------------------  -----------------------------

           ---------------------------------------------------------  -----------------------------
           Signature(s) of Owner(s)                                   Date
           or Authorized Signatory
</TABLE>

    Area Code and Telephone Number: __________

    Must be signed by the Holder(s) of Old Notes as their name(s) appear(s) on
certificates for Old Notes or on a security position listing, or by person(s)
authorized to become registered Holder(s) by endorsement and documents
transmitted with this Notice of Guaranteed Delivery. If signature is by a
trustee, executor, administrator, guardian, attorney-in-fact, officer or other
person acting in a fiduciary or representative capacity, such person must set
forth his or her full title below.
<PAGE>
                      PLEASE PRINT NAME(S) AND ADDRESS(ES)
Name(s): _______________________________________________________________________
Capacity: ______________________________________________________________________
Address(es): ___________________________________________________________________

                                   GUARANTEE
                    (Not to be used for signature guarantee)

    The undersigned, a member firm of a registered national securities exchange
or of the National Association of Securities Dealers, Inc., a commercial bank or
trust company having an office or correspondent in the United States or an
"eligible guarantor institution" within the meaning of Rule 17Ad-15 under the
Securities Exchange Act of 1934, as amended, hereby guarantees that the
certificates representing the principal amount of Old Notes tendered hereby in
proper form for transfer, or timely confirmation of the book-entry transfer of
such Old Notes into the Exchange Agent's account at The Depository Trust Company
pursuant to the procedures set forth in "The Exchange Offer--Guaranteed Delivery
Procedures" section of the Prospectus, together with any required signature
guarantee and any other documents required by the Letter of Transmittal, will be
received by the Exchange Agent at the address set forth above, no later than
three New York Stock Exchange trading days after the date of execution of this
Notice of Guaranteed Delivery.

<TABLE>
<S>                                            <C>
                Name of Firm                               Authorized Signature
                   Address                                         Title
                                                                   Name:
                  Zip Code                                (Please Type or Print)
           Area Code and Tel. No.                                 Dated:
</TABLE>

NOTE: DO NOT SEND CERTIFICATES FOR OLD NOTES WITH THIS FORM. CERTIFICATES FOR
      OLD NOTES SHOULD BE SENT ONLY WITH A COPY OF YOUR PREVIOUSLY EXECUTED
      LETTER OF TRANSMITTAL.
<PAGE>
                 INSTRUCTIONS FOR NOTICE OF GUARANTEED DELIVERY

1.  Delivery of this Notice of Guaranteed Delivery. A properly completed and
    duly executed copy of this Notice of Guaranteed Delivery and any other
    documents required by this Notice of Guaranteed Delivery must be received by
    the Exchange Agent at its address set forth herein prior to 5:00 p.m., New
    York City time, on the Expiration Date. The method of delivery of this
    Notice of Guaranteed Delivery and any other required documents to the
    Exchange Agent is at the election and risk of the Holder and the delivery
    will be deemed made only when actually received by the Exchange Agent. If
    delivery is by mail, registered or certified mail properly insured, with
    return receipt requested, is recommended. In all cases sufficient time
    should be allowed to assure timely delivery. For a description of the
    guaranteed delivery procedure, see Instruction 1 of the Letter of
    Transmittal.

2.  Signatures of this Notice of Guaranteed Delivery. If this Notice of
    Guaranteed Delivery is signed by the registered Holder(s) of the Old Notes
    referred to herein, the signature must correspond with the name(s) written
    on the face of the Old Notes without alteration, enlargement, or any change
    whatsoever. If this Notice of Guaranteed Delivery is signed by a participant
    of the Book-Entry Transfer Facility whose name appears on a security
    position listing as the owner of Old Notes, the signature must correspond
    with the name shown on the security position listing as the owner of the Old
    Notes.

    If this Notice of Guaranteed Delivery is signed by a person other than the
registered Holder(s) of any Old Notes listed or a participant of the Book-Entry
Transfer Facility, this Notice of Guaranteed Delivery must be accompanied by
appropriate bond powers, signed as the name of the registered Holder(s) appears
on the Old Notes or signed as the name of the participant shown on the
Book-Entry Transfer Facility's security position listing.

    If this Notice of Guaranteed Delivery is signed by a trustee, executor,
administrator, guardian, attorney-in-fact, officer of a corporation, or other
person acting in a fiduciary or representative capacity, such person should so
indicate when signing.

3.  Requests for Assistance or Additional Copies. Questions and requests for
    assistance and requests for additional copies of the Prospectus may be
    directed to the Exchange Agent at the address specified in the Prospectus.
    Holders may also contact their broker, dealer, commercial bank, trust
    company, or other nominee for assistance concerning the Exchange Offer.

<PAGE>
                                                                    EXHIBIT 99.4

                         NOTICE OF GUARANTEED DELIVERY
                                      FOR
                          CARRIER1 INTERNATIONAL S.A.
               13 1/4% SENIOR EURO NOTES DUE 2009 (NON-DTC HELD)

    This form or one substantially equivalent hereto must be used to accept the
Exchange Offer of Carrier1, International S.A. (the "Issuer" or the "Company")
made pursuant to the Prospectus, dated            , 1999 (the "Prospectus"), if
certificates (as applicable) for outstanding 13 1/4% Senior Euro Notes Due 2009
(except those which have been deposited with a custodian for, and registered in
the name of, The Depository Trust Company) (the "Old Notes") of the Issuer are
not immediately available or if the procedure for book-entry transfer cannot be
completed on a timely basis or time will not permit all required documents to
reach The Chase Manhattan Bank, as exchange agent (the "Exchange Agent") prior
to 5:00 P.M., New York City time, on the Expiration Date of the Exchange Offer.
Such form may be delivered or transmitted by facsimile transmission, mail or
hand delivery to the Exchange Agent as set forth below. In addition, in order to
utilize the guaranteed delivery procedure to tender Old Notes pursuant to the
Exchange Offer, a completed, signed and dated Letter of Transmittal (or
facsimile thereof) relating to the tender for exchange of Old Notes (the "Letter
of Transmittal") must also be received by the Exchange Agent prior to 5:00 P.M.,
New York City time, on the Expiration Date. Capitalized terms not defined herein
are defined in the Prospectus or the Letter of Transmittal.

             DELIVERY TO: The Chase Manhattan Bank, EXCHANGE AGENT

<TABLE>
<S>                                            <C>
          BY MAIL, HAND DELIVERY OR                        FOR INFORMATION CALL:
             OVERNIGHT CARRIER:                              (44-171) 777-5414

          The Chase Manhattan Bank                    FACSIMILE TRANSMISSION NUMBER:
     Capital Markets Fiduciary Services                      (44-171) 777-5410
            9 Thomas Moore Street
                London E19YT                               CONFIRM BY TELEPHONE:
               United Kingdom                                (44-171) 777-5414
           Attention: Chris Greene
</TABLE>

DELIVERY OF THIS INSTRUMENT TO AN ADDRESS OTHER THAN AS SET FORTH ABOVE, OR
     TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE OTHER THAN AS SET FORTH
                  ABOVE, WILL NOT CONSTITUTE A VALID DELIVERY.

              PLEASE READ THE ACCOMPANYING INSTRUCTIONS CAREFULLY
<PAGE>
Ladies and Gentlemen:

    Upon the terms and conditions set forth in the Prospectus and the
accompanying Letter of Transmittal, the undersigned hereby tenders to the
Company the principal amount of Old Notes set forth below pursuant to the
guaranteed delivery procedure described in "The Exchange Offer--Guaranteed
Delivery Procedures" section of the Prospectus.

<TABLE>
<CAPTION>
 CERTIFICATE NUMBER(S) (IF
   KNOWN) OF EXISTING NOTES
   OR ACCOUNT NUMBER AT THE
     BOOK-ENTRY TRANSFER       AGGREGATE PRINCIPAL AMOUNT    AGGREGATE PRINCIPAL AMOUNT
           FACILITY                   REPRESENTED           TENDERED (IF LESS THAN ALL)*
<S>                           <C>                           <C>
</TABLE>

*   Unless otherwise indicated, the Holder will be deemed to have tendered the
    full aggregate principal amount represented by such Old Notes.

 ALL AUTHORITY HEREIN CONFERRED OR AGREED TO BE CONFERRED SHALL SURVIVE THE
 DEATH OR INCAPACITY OF THE UNDERSIGNED AND EVERY OBLIGATION OF THE UNDERSIGNED
 HEREUNDER SHALL BE BINDING UPON THE HEIRS, PERSONAL REPRESENTATIVES,
 SUCCESSORS AND ASSIGNS OF THE UNDERSIGNED.

                                PLEASE SIGN HERE

<TABLE>
<S>        <C>                                                        <C>
X
X
           Signature(s) of Owner(s)                                   Date
           or Authorized Signatory
</TABLE>

     Area Code and Telephone Number: __________

     Must be signed by the Holder(s) of Old Notes as their name(s) appear(s) on
 certificates for Old Notes or on a security position listing, or by person(s)
 authorized to become registered Holder(s) by endorsement and documents
 transmitted with this Notice of Guaranteed Delivery. If signature is by a
 trustee, executor, administrator, guardian, attorney-in-fact, officer or other
 person acting in a fiduciary or representative capacity, such person must set
 forth his or her full title below.
<PAGE>
                      PLEASE PRINT NAME(S) AND ADDRESS(ES)
 Name(s): _____________________________________________________________________
 Capacity: ____________________________________________________________________
 Address(es): _________________________________________________________________

                                   GUARANTEE
                    (Not to be used for signature guarantee)

     The undersigned, a member firm of a registered national securities
 exchange or of the National Association of Securities Dealers, Inc., a
 commercial bank or trust company having an office or correspondent in the
 United States or an "eligible guarantor institution" within the meaning of
 Rule 17Ad-15 under the Securities Exchange Act of 1934, as amended, hereby
 guarantees that the certificates representing the principal amount of Old
 Notes tendered hereby in proper form for transfer, or timely confirmation of
 the book-entry transfer of such Old Notes into the Exchange Agent's account at
 Euroclear and Cedel Bank pursuant to the procedures set forth in "The Exchange
 Offer-Guaranteed Delivery Procedures" section of the Prospectus, together with
 any required signature guarantee and any other documents required by the
 Letter of Transmittal, will be received by the Exchange Agent at the address
 set forth above, no later than three New York Stock Exchange trading days
 after the date of execution of this Notice of Guaranteed Delivery.

<TABLE>
<S>                                            <C>
                Name of Firm                               Authorized Signature
                   Address                                         Title
                                                                   Name:
                  Zip Code                                (Please Type or Print)
           Area Code and Tel. No.                                 Dated:
</TABLE>

 NOTE: DO NOT SEND CERTIFICATES FOR OLD NOTES WITH THIS FORM. CERTIFICATES FOR
       OLD NOTES SHOULD BE SENT ONLY WITH A COPY OF YOUR PREVIOUSLY EXECUTED
       LETTER OF TRANSMITTAL.
<PAGE>
                 INSTRUCTIONS FOR NOTICE OF GUARANTEED DELIVERY

    1. Delivery of this Notice of Guaranteed Delivery. A properly completed and
duly executed copy of this Notice of Guaranteed Delivery and any other documents
required by this Notice of Guaranteed Delivery must be received by the Exchange
Agent at its address set forth herein prior to 5:00 p.m., New York City time, on
the Expiration Date. The method of delivery of this Notice of Guaranteed
Delivery and any other required documents to the Exchange Agent is at the
election and risk of the Holder and the delivery will be deemed made only when
actually received by the Exchange Agent. If delivery is by mail, registered or
certified mail properly insured, with return receipt requested, is recommended.
In all cases sufficient time should be allowed to assure timely delivery. For a
description of the guaranteed delivery procedure, see Instruction 1 of the
Letter of Transmittal.

    2. Signatures of this Notice of Guaranteed Delivery. If this Notice of
Guaranteed Delivery is signed by the registered Holder(s) of the Old Notes
referred to herein, the signature must correspond with the name(s) written on
the face of the Old Notes without alteration, enlargement, or any change
whatsoever. If this Notice of Guaranteed Delivery is signed by a participant of
the Book-Entry Transfer Facility whose name appears on a security position
listing as the owner of Old Notes, the signature must correspond with the name
shown on the security position listing as the owner of the Old Notes.

    If this Notice of Guaranteed Delivery is signed by a person other than the
registered Holder(s) of any Old Notes listed or a participant of the Book-Entry
Transfer Facility, this Notice of Guaranteed Delivery must be accompanied by
appropriate bond powers, signed as the name of the registered Holder(s) appears
on the Old Notes or signed as the name of the participant shown on the
Book-Entry Transfer Facility's security position listing.

    If this Notice of Guaranteed Delivery is signed by a trustee, executor,
administrator, guardian, attorney-in-fact, officer of a corporation, or other
person acting in a fiduciary or representative capacity, such person should so
indicate when signing.

    3. Requests for Assistance or Additional Copies. Questions and requests for
assistance and requests for additional copies of the Prospectus may be directed
to the Exchange Agent at the address specified in the Prospectus. Holders may
also contact their broker, dealer, commercial bank, trust company, or other
nominee for assistance concerning the Exchange Offer.

<PAGE>
                                                                    EXHIBIT 99.5

                          CARRIER1 INTERNATIONAL S.A.
                       OFFER TO EXCHANGE ALL OUTSTANDING
                    13 1/4% SENIOR DOLLAR NOTES DUE 2009 AND
                 13 1/4% SENIOR EURO NOTES DUE 2009 (DTC HELD)
                                      FOR
                    13 1/4% SENIOR DOLLAR NOTES DUE 2009 AND
                 13 1/4% SENIOR EURO NOTES DUE 2009 (DTC HELD)
                        WHICH HAVE BEEN REGISTERED UNDER
                           THE SECURITIES ACT OF 1933

TO OUR CLIENTS:

    Enclosed for your consideration is a Prospectus, dated         , 1999 (the
"Prospectus"), and the related Letter of Transmittal (the "Letter of
Transmittal"), relating to the offer (the "Exchange Offer") of Carrier1
International S.A. (the "Company") to exchange (i) its 13 1/4% Senior Dollar
Notes due 2009, which have been registered under the Securities Act of 1933, as
amended (the "New Dollar Notes"), for its outstanding 13 1/4% Senior Dollar
Notes due 2009 (the "Old Dollar Notes") and (ii) its 13 1/4% Senior Euro Notes
due 2009, which have been registered under the Securities Act of 1933, as
amended (the "Securities Act") and which are to be deposited with a custodian
for, and registered in the name of, The Depository Trust Company ("DTC") or its
nominee (the "New DTC Euro Notes" and, together with the New Dollar Notes, the
"New Notes"), for its outstanding 13 1/4% Senior Euro Notes due 2009, which have
been deposited with a custodian for, and registered in the name of, DTC or its
nominee (the "Old DTC Euro Notes" and, together with the Old Dollar Notes, the
"Old Notes"), upon the terms and subject to the conditions described in the
Prospectus and the Letter of Transmittal. The Exchange Offer is being made in
order to satisfy certain obligations of the Company contained in the Notes
Registration Rights Agreement dated February 12, 1999, by and among the Company
and the placement agents referred to therein.

    This material is being forwarded to you as the beneficial owner of the Old
Notes held by us for your account but not registered in your name. A TENDER OF
SUCH OLD NOTES MAY ONLY BE MADE BY US AS THE HOLDER OF RECORD AND PURSUANT TO
YOUR INSTRUCTIONS.

    Accordingly, we request instructions as to whether you wish us to tender on
your behalf the Old Notes held by us for your account, pursuant to the terms and
conditions set forth in the enclosed Prospectus and Letter of Transmittal.

    Your instructions should be forwarded to us as promptly as possible in order
to permit us to tender the Old Notes on your behalf in accordance with the
provisions of the Exchange Offer. The Exchange Offer will expire at 5:00 P.M.,
New York City time, on       , 1999, unless extended by the Company. Any Old
Notes tendered pursuant to the Exchange Offer may be withdrawn at any time
before the Expiration Date.

    Your attention is directed to the following:

1.  The Exchange Offer is for any and all Old Notes.

2.  The Exchange Offer is subject to certain conditions set forth in the
    Prospectus in the section captioned "The Exchange Offer--Conditions."

3.  Any transfer taxes incident to the transfer of Old Notes from the holder to
    the Company will be paid by the Company, except as otherwise provided in the
    Instructions in the Letter of Transmittal.

4.  The Exchange Offer expires at 5:00 P.M., New York City time, on       ,
    1999, unless extended by the Company.

    If you wish to have us tender your Old Notes, please so instruct us by
completing, executing and returning to us the instruction form on the back of
this letter. THE LETTER OF TRANSMITTAL IS FURNISHED TO YOU FOR INFORMATION ONLY
AND MAY NOT BE USED DIRECTLY BY YOU TO TENDER OLD NOTES.
<PAGE>
                          INSTRUCTIONS WITH RESPECT TO
                               THE EXCHANGE OFFER

    The undersigned acknowledge(s) receipt of your letter and the enclosed
material referred to therein relating to the Exchange Offer made by Carrier1
International S.A. with respect to its Old Notes.

    This will instruct you to tender the Old Notes held by you for the account
of the undersigned, upon and subject to the terms and conditions set forth in
the Prospectus and the related Letter of Transmittal.

    The aggregate principal amount of Old Notes held by you for the account of
the undersigned is (fill in amounts, as applicable):

    $ _________ of 13 1/4% Senior Dollar Notes due 2009.

    / / _________ of 13 1/4% Senior Euro Notes due 2009 (DTC Held).

    With respect to the Exchange Offer, the undersigned hereby instructs you
(check appropriate box):

        / / To TENDER the following Old Notes held by you for the account of the
            undersigned (insert principal amount of each series of Old Notes to
            be tendered (if any)):

               $ _________ of 13 1/4% Senior Dollar Notes due 2009.

               / / _________ of 13 1/4% Senior Euro Notes due 2009 (DTC Held).

           / / NOT to TENDER any Old Notes held by you for the account of the
       undersigned.

    If the undersigned instructs you to tender Old Notes held by you for the
account of the undersigned, it is understood that you are authorized to make, on
behalf of the undersigned (and the undersigned, by its signature below, hereby
makes to you), the representations and warranties contained in the Letter of
Transmittal that are to be made with respect to the undersigned as a beneficial
owner, including but not limited to the representations that (i) the New Notes
acquired pursuant to the Exchange Offer are being acquired in the ordinary
course of business of the person receiving such New Notes, whether or not such
person is the undersigned, (ii) neither the undersigned nor any such other
person is participating in, intends to participate in or has an arrangement or
understanding with any person to participate in the distribution (within the
meaning of the Securities Act) of Old Notes or New Notes, (iii) neither the
undersigned nor any such other person is an "affiliate," as defined in Rule 405
under the Securities Act, of the Company, and (iv) neither the undersigned nor
any such other person is acting on behalf of any person who could not truthfully
make the foregoing representations and warranties. If the undersigned is a
broker-dealer that will receive New Notes for its own account in exchange for
Old Notes, it represents that the Old Notes to be exchanged for the New Notes
were acquired by it as a result of market-making activities or other trading
activities and acknowledges that it will deliver a prospectus meeting the
requirements of the Securities Act in connection with any resale of such New
Notes; however, by so acknowledging and by delivering a prospectus meeting the
requirements of the Securities Act, the undersigned will not be deemed to admit
that it is an "underwriter" within the meaning of the Securities Act.
<PAGE>
                                   SIGN HERE

Dated: __________________________________________________________________ , 1999

Signature(s): __________________________________________________________________

Print name(s) here: ____________________________________________________________

Print Address(es): _____________________________________________________________

Area Code and Telephone Number(s): _____________________________________________

Tax Identification or Social Security Number(s): _______________________________

    None of the Old Notes held by us for your account will be tendered unless we
receive written instructions from you to do so. Unless a specific contrary
instruction is given in the space provided, your signature(s) hereon shall
constitute an instruction to us to tender all the Old Notes held by us for your
account.

<PAGE>
                                                                    EXHIBIT 99.6

                          CARRIER1 INTERNATIONAL S.A.
                       OFFER TO EXCHANGE ALL OUTSTANDING
               13 1/4% SENIOR EURO NOTES DUE 2009 (NON-DTC HELD)
                                      FOR
               13 1/4% SENIOR EURO NOTES DUE 2009 (NON-DTC HELD)
                        WHICH HAVE BEEN REGISTERED UNDER
                           THE SECURITIES ACT OF 1933

TO OUR CLIENTS:

    Enclosed for your consideration is a Prospectus, dated         , 1999 (the
"Prospectus"), and the related Letter of Transmittal (the "Letter of
Transmittal"), relating to the offer (the "Exchange Offer") of Carrier1
International S.A. (the "Company") to exchange its 13 1/4% Senior Euro Notes due
2009, which have been registered under the Securities Act of 1933, as amended
(the "Securities Act"), and which are to be deposited with a custodian for, and
registered in the name of, The Depository Trust Company or its nominee (the "New
Notes"), for its outstanding 13 1/4% Senior Euro Notes due 2009, which have been
deposited with a custodian for, and registered in the name of, The Depository
Trust Company or its nominee (the "Old Notes"), upon the terms and subject to
the conditions described in the Prospectus and the Letter of Transmittal. The
Exchange Offer is being made in order to satisfy certain obligations of the
Company contained in the Notes Registration Rights Agreement dated February 12,
1999, by and among the Company and the placement agents referred to therein.

    This material is being forwarded to you as the beneficial owner of the Old
Notes held by us for your account but not registered in your name. A TENDER OF
SUCH OLD NOTES MAY ONLY BE MADE BY US AS THE HOLDER OF RECORD AND PURSUANT TO
YOUR INSTRUCTIONS.

    Accordingly, we request instructions as to whether you wish us to tender on
your behalf the Old Notes held by us for your account, pursuant to the terms and
conditions set forth in the enclosed Prospectus and Letter of Transmittal.

    Your instructions should be forwarded to us as promptly as possible in order
to permit us to tender the Old Notes on your behalf in accordance with the
provisions of the Exchange Offer. The Exchange Offer will expire at 5:00 P.M.,
New York City time, on             , 1999, unless extended by the Company. Any
Old Notes tendered pursuant to the Exchange Offer may be withdrawn at any time
before the Expiration Date.

    Your attention is directed to the following:

    1. The Exchange Offer is for any and all Old Notes.

    2. The Exchange Offer is subject to certain conditions set forth in the
Prospectus in the section captioned "The Exchange Offer--Conditions."

    3. Any transfer taxes incident to the transfer of Old Notes from the holder
to the Company will be paid by the Company, except as otherwise provided in the
Instructions in the Letter of Transmittal.

    4. The Exchange Offer expires at 5:00 P.M., New York City time, on
            , 1999, unless extended by the Company.

    If you wish to have us tender your Old Notes, please so instruct us by
completing, executing and returning to us the instruction form on the back of
this letter. THE LETTER OF TRANSMITTAL IS FURNISHED TO YOU FOR INFORMATION ONLY
AND MAY NOT BE USED DIRECTLY BY YOU TO TENDER OLD NOTES.
<PAGE>
                          INSTRUCTIONS WITH RESPECT TO
                               THE EXCHANGE OFFER

    The undersigned acknowledge(s) receipt of your letter and the enclosed
material referred to therein relating to the Exchange Offer made by Carrier1
International S.A. with respect to its Old Notes.

    This will instruct you to tender the Old Notes held by you for the account
of the undersigned, upon and subject to the terms and conditions set forth in
the Prospectus and the related Letter of Transmittal.

    The aggregate principal amount of Old Notes held by you for the account of
the undersigned is (fill in amounts, as applicable):

    / / _________ of 13 1/4% Senior Euro Notes due 2009.

    With respect to the Exchange Offer, the undersigned hereby instructs you
(check appropriate box):

           / / To TENDER the following Old Notes held by you for the account of
               the undersigned (insert principal amount of Old Notes to be
               tendered (if any)):

               / / _________ of 13 1/4% Senior Euro Notes due 2009.

           / / NOT to TENDER any Old Notes held by you for the account of the
       undersigned.

    If the undersigned instructs you to tender Old Notes held by you for the
account of the undersigned, it is understood that you are authorized to make, on
behalf of the undersigned (and the undersigned, by its signature below, hereby
makes to you), the representations and warranties contained in the Letter of
Transmittal that are to be made with respect to the undersigned as a beneficial
owner, including but not limited to the representations that (i) the New Notes
acquired pursuant to the Exchange Offer are being acquired in the ordinary
course of business of the person receiving such New Notes, whether or not such
person is the undersigned, (ii) neither the undersigned nor any such other
person is participating in, intends to participate in or has an arrangement or
understanding with any person to participate in the distribution (within the
meaning of the Securities Act) of Old Notes or New Notes, (iii) neither the
undersigned nor any such other person is an "affiliate," as defined in Rule 405
under the Securities Act, of the Company, and (iv) neither the undersigned nor
any such other person is acting on behalf of any person who could not truthfully
make the foregoing representations and warranties. If the undersigned is a
broker-dealer that will receive New Notes for its own account in exchange for
Old Notes, it represents that the Old Notes to be exchanged for the New Notes
were acquired by it as a result of market-making activities or other trading
activities and acknowledges that it will deliver a prospectus meeting the
requirements of the Securities Act in connection with any resale of such New
Notes; however, by so acknowledging and by delivering a prospectus meeting the
requirements of the Securities Act, the undersigned will not be deemed to admit
that it is an "underwriter" within the meaning of the Securities Act.
<PAGE>
                                   SIGN HERE

Dated: __________________________________________________________________ , 1999

Signature(s): __________________________________________________________________

Print name(s) here: ____________________________________________________________

Print Address(es): _____________________________________________________________

Area Code and Telephone Number(s): _____________________________________________

Tax Identification or Social Security Number(s): _______________________________

    None of the Old Notes held by us for your account will be tendered unless we
receive written instructions from you to do so. Unless a specific contrary
instruction is given in the space provided, your signature(s) hereon shall
constitute an instruction to us to tender all the Old Notes held by us for your
account.


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