TELEHUB COMMUNICATIONS CORP
8-K, 1999-06-02
TELEPHONE COMMUNICATIONS (NO RADIOTELEPHONE)
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                     U.S. SECURITIES AND EXCHANGE COMMISSION
                                Washington, D.C.



                                    FORM 8-K

  Current Report pursuant to Section 13 of the Securities Exchange Act of 1934




                          Date of Report: May 19, 1999


                       TELEHUB COMMUNICATIONS CORPORATION
             (Exact Name of Registrant as Specified in its Charter)

       Nevada                       333-61441                 36-413-6730
 (Jurisdiction of                 (Commission               (I.R.S. Employer
  incorporation)                  File Number)           Identification Number)

                                 CO-REGISTRANTS
                                 --------------
                      TeleHub Network Services Corporation
                        TeleHub Technologies Corporation
                           TeleHub Leasing Corporation
          (Exact Name of Co-Registrants as Specified in their Charters)
    Illinois                        333-61441                 36-406-6622
     Nevada                         333-61441                 36-421-3797
     Nevada                        333-61441                  36-335-3108
(Jurisdiction of                  (Commission               (I.R.S. Employer
 incorporation)                   File Number)           Identification Number)




                     John R. Lawson, Chief Financial Officer
                       TeleHub Communications Corporation
                             1175 Tri-State Parkway
                             Gurnee, Illinois 60031
                                 1 (800) TELEHUB
                (Address, including zip code, & telephone number,
                  of Registrants' principal executive offices)






<PAGE>


Item 2.  Acquisition or Disposition of Assets

         On  May  19,  1999,  TeleHub  Communications   Corporation,   a  Nevada
corporation   ("Registrant")  consummated  a  strategic  joint  venture  ("Joint
Venture")  with  Newbridge   Networks   Corporation,   a  Canadian   corporation
("Newbridge") as described in Item 2 of Registrant's  current report on SEC Form
8-K dated March 31, 1999.  Registrant  and  Newbridge  announced  closing of the
Joint  Venture on May 25, 1999,  through the  attached  Press  Release  (Exhibit
99.4).


Item 5.  Other Events

         Formation and implementation of the Joint Venture (Item 2) necessitated
amendments  ("Amendments",  described  below)  to  the  Indenture  ("Indenture",
Exhibit 4.1 to  Registration  Statement  #333-61441  on SEC Form S-4)  governing
Registrant's   Series  B  Senior   Notes   due   2005   ("Notes").   Registrant,
Co-Registrants  and  Trustee,  after  obtaining  consent  of  the  Note  holders
("Noteholders")  adopted the  Amendments  by  executing  the First  Supplemental
Indenture ("Supplemental Indenture", Exhibit 4.5).

         Adoption of the  Amendments  and  Supplemental  Indenture  required the
written  consent of the  holders of at least a majority in  principal  amount at
maturity of the outstanding Notes.  Accordingly,  Registrant  prepared a Consent
Solicitation   Statement  ("Consent   Solicitation")   specifying  the  proposed
Amendments.  In the Consent  Solicitation,  Registrants  offered a cash  payment
("Consent  Payment")  of  1.375%  of  the  Accreted  Value  (as  defined  in the
Indenture) of the Notes held by consenting Noteholders.  The Registrants offered
an  additional  0.125% cash  payment  ("Irrevocable  Consent  Payment")  to each
Noteholder  who  delivered an  irrevocable  Consent  prior to  expiration of the
consent  solicitation  period. The Consent  Solicitation  expressly informed the
Noteholders  that if the requisite  Consents were obtained,  Noteholders who did
not consent to the proposed Amendments would not receive any Consent Payment but
would nevertheless be bound by the proposed Amendments.

     The  Amendments  amended  certain  covenants  and other  provisions  in the
Indenture, principally:

o        The definition of  "Investment"  was   revised  to authorize the  Joint
         Venture.
o        The  definition  of  "Permitted   Investment"  was  revised  to  permit
         Registrant  to invest up to $10  million  in its  TeleHub  Technologies
         Corporation ("TTC") subsidiary and other affiliates.
o        The definition  of  "Subsidiary"  was  revised  to  exclude  TERAbridge
         Technologies Corporation ("TERAbridge") therefrom. This amendment means
         that TERAbridge will not guarantee the Notes.
o        Since  TERAbridge  will not  guarantee  the Notes,  Registrant  and TTC
         agreed to pledge their stock in TTC and  TERAbridge,  respectively,  to
         State  Street  Bank and  Trust  Company  ("Collateral  Agent")  for the
         benefit  of the  Noteholders.  Registrant,  TTC  and  Collateral  Agent
         executed a Pledge Agreement  (Exhibit 4.6) to effectuate this pledge. A
         new  Article 11  specifies  the  parties'  duties  with  respect to the
         pledged TTC and TERAbridge stock.




                                       1
<PAGE>

o        Article 11 also grants a continuing  first priority  security  interest
         under the Pledge  Agreement in favor of the  Noteholders  in any future
         investments by Registrants in TTC or TERAbridge.
o        Section 4.14,  "Asset  Sales" was revised to require  Registrant to use
         the  net  proceeds   from  any  future  sales  of  TTC  or   TERAbridge
         stock held by Registrant or any Subsidiary or from any TTC Distribution
         to make an offer  to purchase  Notes  pursuant  to  the  provisions  of
         Section 4.14.
o        The  Supplemental  Indenture did not,  among other  things,  reduce the
         principal  amount at maturity of the Notes, did not reduce the interest
         rate  under  the  Notes  and did not  change  the time for  payment  of
         interest under the Notes.
o        Section  4.8,  "Limitation  on the  Incurrence  of  Indebtedness,"  was
         modified  to  permit  the  Registrant  to  incur up to $30  million  of
         Indebtedness (including up to $20 million for equipment financing).

     Holders of  approximately  99.7% of the outstanding  Notes consented to the
Amendments.  Registrants  made the  Consent  Payments  and  Irrevocable  Consent
Payments to  consenting  Noteholders  as of May 19,  1999 when the  Supplemental
Indenture  became  effective.  Consequently,  the  Indenture  is now  amended as
specified in the Supplemental Indenture.


Item 7.    Financial Statements and Exhibits
       (a) Financial Statements of Businesses Acquired.    None Required.
       (b) Pro Forma Financial Information.  Not Applicable.
       (c) Exhibits
               (4)  Instruments defining the rights of security holders
                      (4.5)  Supplemental Indenture dated  May  19,  1999 by and
                             among  Registrant, Co-Registrants  and Trustee
                      (4.6)  Pledge  Agreement  dated May 19, 1999 by  and among
                             Registrant, TTC and Collateral Agent

               (99) Additional Exhibits
                      (99.4) Press  Release  announcing  consummation  of  Joint
                             Venture, dated May 25, 1999












                                       2
<PAGE>


                                    SIGNATURE

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrants  have duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorized.

                                 TELEHUB COMMUNICATIONS CORPORATION
                                 TELEHUB NETWORK SERVICES CORPORATION
                                 TELEHUB TECHNOLOGIES CORPORATION
                                 TELEHUB LEASING CORPORATION

June 2, 1999                     By: /s/ JOHN R. LAWSON
                                       ----------------------------------------
                                       John R. Lawson, Chief Financial Officer
                                       of each Registrant
















































                                       3
<PAGE>


                                  EXHIBIT INDEX

Exhibit
Category     Description and Exhibit Number
- --------     ------------------------------

(4)          Instruments defining the rights of security holders
               (4.5)    Supplemental Indenture dated May 19, 1999
                        by and among Registrant, Co-Registrants
                        and Trustee
               (4.6)    Pledge Agreement dated May 19, 1999
                        by and among Pledgors and Collateral Agent

(99)         Additional Exhibits
               (99.4)   Press Release announcing consummation of
                        Joint Venture, dated May 25, 1999






























                                       4



                                                                     EXHIBIT 4.5




                          FIRST SUPPLEMENTAL INDENTURE

                            Dated as of May 19, 1999

                                  by and among

                       TELEHUB COMMUNICATIONS CORPORATION,
                                   as Issuer,

                      TELEHUB NETWORK SERVICES CORPORATION,
                      TELEHUB TECHNOLOGIES CORPORATION, and
                          TELEHUB LEASING CORPORATION,
                                 as Guarantors,

                                       and

                      STATE STREET BANK AND TRUST COMPANY,
                                   as Trustee

                                       to

                                    INDENTURE

                            dated as of July 30, 1998

             Relating to $125,000,000 Aggregate Principal Amount of

                     13-7/8% Senior Discount Notes due 2005



<PAGE>




                          FIRST SUPPLEMENTAL INDENTURE

         This  FIRST  SUPPLEMENTAL  INDENTURE,  dated as of May 19,  1999  (this
"Supplement"),  by  and  among  TELEHUB  COMMUNICATIONS  CORPORATION,  a  Nevada
corporation (the "Company"),  TELEHUB NETWORK SERVICES CORPORATION,  an Illinois
Corporation  ("TNS"),  TELEHUB  TECHNOLOGIES  CORPORATION,  a Nevada Corporation
("TLC," and collectively with TNS and TTC, the  "Guarantors"),  and STATE STREET
BANK AND TRUST COMPANY, a Massachusetts trust company, as trustee ("Trustee").

                                   WITNESSETH:

         WHEREAS, the Company, the Guarantors and the Trustee are parties to the
Indenture,  dated as of July 30, 1998, pursuant to which $125,000,000  aggregate
principal  amount of the Company's 13-7/8% Senior  Discount  Notes due 2005 were
issued and with respect to which this Supplement relates;

         WHEREAS,  the Company  desires to amend the Indenture in the manner set
forth in this Supplement;

         WHEREAS, Section 9.2 of the Indenture provides that the Company and the
Trustee may from time to time amend or supplement the Indenture with the receipt
of consent of the Holders of at least a majority in aggregate  principal  amount
of the then outstanding Notes;

         WHEREAS,   the   Company   undertook   a  consent   solicitation   (the
"Solicitation")  seeking the written consent from Holders  pursuant to a Consent
Solicitation Statement dated April 5, 1999 (the "Solicitation Statement");

         WHEREAS, the Company has received in the Solicitation the valid written
consents of the Holders of more than a majority in aggregate principal amount of
the outstanding  Notes,  consenting to the substance of the amendments set forth
in this Supplement;

         WHEREAS,  all  conditions  and  requirements  necessary  to  make  this
Supplement a valid, binding and legal instrument in accordance with the terms of
the Indenture  have been  performed and fulfilled and the execution and delivery
hereof have been in all respect duly authorized; and

         WHEREAS, in accordance with the terms of the Indenture, the Company has
requested that the Trustee execute and deliver this Supplement;

         NOW  THEREFORE,  in  consideration  of the above  premises,  each party
agrees,  for the benefit of the other and for the equal and valuable  benefit of
the Holders of Notes, as follows:











                      First Supplemental Indenture: Page 1

<PAGE>




                       ARTICLE 1: DEFINITIONAL AMENDMENTS

         Section  1.1 First  Definitional  Amendment.  The  Indenture  is hereby
amended to modify the definition of "Asset Sale" to add new clauses (iv) and (v)
which will exclude the Newbridge  Transaction  and any Newco  Sale/Distribution,
respectively, from the definition thereof, as follows:

                  "Asset Sale" means (i) the sale,  lease,  conveyance  or other
         disposition of any assets (including,  without limitation,  by way of a
         sale and  leaseback),  other than sales of  inventory  in the  ordinary
         course of business  consistent  with past practices  (provided that the
         sale,  lease,  conveyance or other  disposition of all or substantially
         all of the assets of the Company and its Subsidiaries  taken as a whole
         will be governed by the  provisions  of Section  4.15 and/or  Article 5
         hereof,  and not by the provisions  Section 4.14 hereof),  and (ii) the
         issue  or sale by the  Company  or any of its  Subsidiaries  of  Equity
         Interests  of any of the  Company's  Subsidiaries,  whether in a single
         transaction  or a series of related  transactions  (a) that have a fair
         market  value in  excess of $1.0  million  or (b) for net  proceeds  in
         excess of $1.0 million.  Notwithstanding the foregoing:  (i) a transfer
         of assets by the Company to a Wholly  Owned  Subsidiary  or by a Wholly
         Owned Subsidiary to the Company or to another Wholly Owned  Subsidiary,
         (ii) a  Restricted  Payment  that is  permitted  by Section 4.9 hereof,
         (iii) a TNS/TTC  Transaction,  (iv) any sale of any Equity Interests of
         Newco by the Company or Newco in connection with the Newbridge  Initial
         Investment   and   the   Newbridge   Transaction,   and   (v)  a  Newco
         Sale/Distribution will not be deemed to be an Asset Sale.

         Section 1.2 Second  Definitional  Amendment.  The  Indenture  is hereby
amended to add a new defined term "Collateral" thereto, as follows:

                  "Collateral" has the meaning ascribed to such  term  under the
         Pledge Agreement.

         Section  1.3 Third  Definitional  Amendment.  The  Indenture  is hereby
amended to add a new defined term "Collateral Agent" thereto, as follows:

                  "Collateral  Agent" means State Street Bank and Trust Company,
         in its capacity as collateral agent under the Collateral Document until
         a successor  replaces it in accordance  with  applicable  provisions of
         this Indenture, and thereafter means the successor serving hereunder.

         Section 1.4 Fourth  Definitional  Amendment.  The  Indenture  is hereby
amended to add the new defined term "Collateral Document" thereto, as follows:





                      First Supplemental Indenture: Page 2

<PAGE>




                  "Collateral Document" means the Pledge Agreement,  dated as of
         May 19, 1999, by and between the Company, TTC and the Collateral Agent,
         granting and governing the Security Interest.

         Section  1.5 Fifth  Definitional  Amendment.  The  Indenture  is hereby
amended to modify the definition of "Investments" to add a proviso to the end of
the definition thereof which will authorize the Newbridge Initial Investment and
the Proposed Transaction, as follows:

                  "Investments"   means,   with  respect  to  any  Person,   all
         investments by such Person in other Persons  (including  Affiliates) in
         the  forms  of  direct  or  indirect  loans  (including  guarantees  of
         Indebtedness or other obligations),  advances or capital  contributions
         (excluding  commission,  travel and similar  advances  to officers  and
         employees made in the ordinary course of business),  purchases or other
         acquisitions for  consideration  of  Indebtedness,  Equity Interests or
         other  securities,  together  with  all  items  that  are or  would  be
         classified as  investments  on a balance  sheet  prepared in accordance
         with GAAP; provided that an acquisition of assets,  Equity Interests or
         other  securities  by  the  Company  or any  of  its  Subsidiaries  for
         consideration  consisting  of common  equity  securities of the Company
         shall  not  be  deemed  to be an  Investment.  If  the  Company  or any
         Subsidiary  of the Company  sells or  otherwise  disposes of any Equity
         Interests  of any direct or indirect  Subsidiary  of the  Company  such
         that, after giving effect to any sale or disposition, such Person is no
         longer a Subsidiary of the Company, the Company shall be deemed to have
         made an Investment on the date of any such sale or disposition equal to
         the fair market value of the Equity  Interests of such  Subsidiary  not
         sold or disposed of in an amount  determined as provided in Section 4.9
         hereof; provided, however, that the Newco Contribution and the issuance
         in exchange  therefore of Equity  Interests of Newco to the Company and
         TTC shall not be deemed to be an Investment.

         Section 1.6 Sixth Amendment  Definitional  Amendment.  The Indenture is
hereby amended to modify the  definition of "Net Proceeds" to include  reference
in the second, fourth and ninth lines thereof to proceeds received in respect of
a Newco Sale/Distribution, as follows:

                  "Net  Proceeds"  means the  aggregate  cash  proceeds or other
         value received by the Company or any of its  Subsidiaries in respect of
         any  Asset  Sale  or  Newco  Sale/  Distribution  (including,   without
         limitation, any cash received upon the sale or other disposition of any
         non-cash  consideration  received  in any  Asset  Sale or  Newco  Sale/
         Distribution),  net of the direct costs  relating to such Asset Sale or
         Newco  Sale/  Distribution  (including,   without  limitation,   legal,
         accounting and investment banking fees, and sales





                      First Supplemental Indenture: Page 3

<PAGE>




         commissions), any relocation expenses incurred as a result thereof, any
         taxes paid or payable by the  Company or any of its  Subsidiaries  as a
         result  thereof (after taking into account any available tax credits or
         deductions and any tax sharing  arrangements),  amounts  required to be
         applied to the repayment of Indebtedness secured by a Lien on the asset
         or assets  that were the subject of such Asset Sale and any reserve for
         adjustment  in  respect  of the  sale  price of such  asset  or  assets
         established in accordance with GAAP.

         Section 1.7 Seventh  Definitional  Amendment.  The  Indenture is hereby
amended to add a new defined term "Newbridge" thereto, as follows:

                  "Newbridge" shall mean Newbridge Networks Corporation, a
         Canadian corporation.

         Section 1.8 Eighth  Definitional  Amendment.  The  Indenture  is hereby
amended to add a new defined term "Newbridge  Initial  Investment"  thereto,  as
follows:

                  "Newbridge  Initial  Investment" shall mean the acquisition by
         Newbridge  of the initial 19%  interest  in Newco  contemplated  by the
         Newbridge Transaction pursuant to the Newbridge Transaction Agreement
         and Stockholders Agreement.

         Section  1.9 Ninth  Definitional  Amendment.  The  Indenture  is hereby
amended to add a new defined term "Newbridge Transaction" thereto, as follows:

                  "Newbridge Transaction" shall mean the strategic joint venture
         between Newbridge and the Company,  whereby (i) Newco will be formed as
         a  Nevada   corporation;   (ii)  the  Company  and  TTC  will  transfer
         substantially all of their respective VASP(TM)-related assets to Newco,
         in exchange for all of the outstanding Equity Interests of Newco; (iii)
         the Company will sell all of its Equity Interests in Newco to Newbridge
         thereby making  Newbridge and TTC the sole  shareholders  of Newco with
         TTC owning 81% and  Newbridge  owning 19% of the Common Stock  thereof;
         (iv) Newco will grant the Company  and TNS a  perpetual  license to use
         VASP(TM) as specified in such license in their  products and  services;
         (v) Newco will issue  certain  shares of its common stock to Newbridge;
         (vi) Newco will repay certain  Indebtedness owed by TTC to the Company;
         and (vii)  Newco will grant to  Newbridge  the option to  purchase  the
         number of Equity  Interests  necessary  for Newbridge to own 50% of the
         issued  and  outstanding   Equity  Interests  in  Newco,  all  as  more
         particularly  described in the  Newbridge  Transaction  Agreement,  the
         Stockholders  Agreement  and the Option  Agreement  (as  defined in the
         Newbridge Transaction Agreement).





                      First Supplemental Indenture: Page 4

<PAGE>




         Section  1.10 Tenth  Definitional  Amendment.  The  Indenture is hereby
amended to add a new defined term "Newbridge  Transaction Agreement" thereto, as
follows:

                  "Newbridge  Transaction  Agreement"  shall  mean that  certain
         Organizational Agreement,  dated as of March 31, 1999, by and among the
         Company,  TTC,  Newco  and  Newbridge,  as in effect on the date of the
         Supplemental Indenture.

         Section 1.11 Eleventh Definitional  Amendment.  The Indenture is hereby
amended to add a new defined term "Newco" thereto, as follows:

         "Newco" means TERABridge Technologies Corporation, a Nevada
         corporation.

         Section 1.12 Twelfth  Definitional  Amendment.  The Indenture is hereby
amended to add a new defined term "Newco Contribution" thereto, as follows:

                  "Newco   Contribution"   shall   mean  the   contribution   of
         VASP(TM)-related assets to Newco by the Company and TTC as contemplated
         by the Newbridge Transaction Agreement.

         Section 1.13 Thirteenth Definitional Amendment. The Indenture is hereby
amended to add a new defined term "Newco Sale/Distribution" thereto, as follows:

                  "Newco Sale/Distribution" means the sale, lease, conveyance or
         other  disposition  by TTC or Newco of any assets of TTC or Newco other
         than in the ordinary course of business  consistent with past practice,
         in  which  (in  the  case  of  a  sale,  lease,  conveyance,  or  other
         disposition  by Newco only) Newco  dividends,  distributes or otherwise
         pays any net cash proceeds from such sale,  lease,  conveyance or other
         disposition,  as  the  case  may  be,  to  the  Company  or  any of its
         Subsidiaries.

         Section 1.14 Fourteenth Definitional Amendment. The Indenture is hereby
amended to modify the definition of "Permitted  Investments" to (a) increase the
amount that the  Company  may invest in TTC or Newco from $3.0  million to $10.0
million,  by  amending  the  proviso  in clause  (vi)  thereof  to delete  "$3.0
million," and insert in its place "$10.0 million," (b) permit any Investments in
Newco by TTC made  after the  Newbridge  Initial  Investment  and (c) permit the
Newco Contribution, as follows:

                  "Permitted  Investments"  means  (i)  any  Investment  in  the
         Company or in a Wholly  Owned  Subsidiary  of the  Company  (other than
         TTC); (ii) any Investment in Cash Equivalents;  (iii) any Investment by
         the Company or any of its  Subsidiaries  in a Person if, as a result of
         such Investment, (a) such







                      First Supplemental Indenture: Page 5

<PAGE>




         Person  becomes a Wholly  Owned  Subsidiary  of the Company or (b) such
         Person  is  merged,  consolidated  or  amalgamated  with  or  into,  or
         transfers  or  conveys  substantially  all  of  its  assets  to,  or is
         liquidated  into,  the  Company  or a Wholly  Owned  Subsidiary  of the
         Company;  (iv) any Investment  existing on the date of this  Indenture;
         (v)  any  Investment  made  as a  result  of the  receipt  of  non-cash
         consideration  from an Asset  Sale  that was  made  pursuant  to and in
         compliance  with  Section 4.14 hereof;  (vi) other  Investments  in any
         Person  (other  than (x) an  Affiliate  that is not a  Subsidiary  or a
         Person that is controlled by an Affiliate  that is not a Subsidiary and
         (y) Newco) engaged in a line of business that is similar, complementary
         or ancillary  to the business of the Company on the Issue Date,  not to
         exceed $3.0 million,  provided,  that,  every $1.00 of Investment above
         $7.0  million  made by the Company  under  clause  (vii) will reduce by
         $1.00 the amount  available for  Investment  under this clause (vi); or
         (vii) any  Investments  in  either  TTC or Newco  made  after the Newco
         Contribution  and the Newbridge  Initial  Investment  that,  when taken
         together with all other Investments made pursuant to this clause (vii),
         do not, in the aggregate, exceed $10.0 million, provided, however, that
         every $1.00 of Investment  by the Company or a Wholly Owned  Subsidiary
         under clause (vi) will reduce by $1.00 the amount  available under this
         clause (vii), and, provided  further,  however,  that to the extent the
         Company  makes any  Investment  in TTC, TTC shall  further  invest such
         Investment  in  Newco,  and,  provided  further,   however,  that  each
         Investment  under  this  clause  (vii) is  evidenced  by an  instrument
         pledged  under  the  Pledge  Agreement  so as to  create a valid  first
         priority Lien thereon for the benefit of the Holders.

         Section 1.15 Fifteenth Definitional Amendment.  The Indenture is hereby
amended to modify  definition  of  "Permitted  Liens" by adding (a) a new clause
(xiii) which will reference Liens on Collateral to the extent existing by virtue
of the  Collateral  Document and (b) a new clause (xiv) which will reference any
Liens to the extent granted under the Stockholders Agreement, as follows:

                  "Permitted  Liens"  means (i) Liens  securing  the Bank Credit
         Facility;   (ii)  Liens  in  favor  of  the   Company  or  any  of  its
         Subsidiaries;  (iii) Liens on property of a Person existing at the time
         such Person is merged into or  consolidated  with the Company or any of
         its  Subsidiaries,  provided that such Liens were in existence prior to
         the  contemplation of such merger or consolidation and do not extend to
         any assets other than those of the Person  merged into or  consolidated
         with  the  Company  or any such  Subsidiary;  (iv)  Liens  on  property
         existing  at the time of  acquisition  thereof by the Company or any of
         its  Subsidiaries,  provided that such Liens were in existence prior to
         the  contemplation  of  such  acquisition;  (v)  Liens  to  secure  the
         performance   of  statutory   obligations,   surety  or  appeal  bonds,
         performance bonds or other





                      First Supplemental Indenture: Page 6

<PAGE>




         obligations  of a like  nature  incurred  in  the  ordinary  course  of
         business;  (vi)  Liens to  secure  Indebtedness  permitted  by  Section
         4.8(iv)(A)   hereof   covering  only  the  assets  acquired  with  such
         Indebtedness;  (vii)  Liens  existing  on the  date of  this  Indenture
         excluding  Liens on  Indebtedness to be repaid with the proceeds of the
         Offering;  (viii) Liens for taxes,  assessments or governmental charges
         or claims that are not yet  delinquent  or that are being  contested in
         good  faith  by  appropriate   proceedings   promptly   instituted  and
         diligently  concluded,  provided that any reserve or other  appropriate
         provision as shall be required in conformity  with GAAP shall have been
         made therefor;  (ix) Liens incurred in the ordinary  course of business
         of the Company or any of its  Subsidiaries  with respect to obligations
         that do not exceed $2.0  million at any one time  outstanding  and that
         (a) are not incurred in  connection  with the borrowing of money or the
         obtaining  of  advances  or  credit  (other  than  trade  credit in the
         ordinary course of business) and (b) do not in the aggregate materially
         detract  from the value of the  property or  materially  impair the use
         thereof  in the  operation  of  business  by the  Company  or any  such
         Subsidiary;  (x)  renewals or  refundings  of any Liens  referred to in
         clauses  (iii)  through (ix) above,  provided  that any such renewal or
         refunding does not extend to any assets or secure any  Indebtedness not
         securing or secured by the Liens being renewed or refinanced;  (xi) any
         Lien  consisting of a deposit or pledge made in the ordinary  course of
         business in connection with, or to secure payment of, obligations under
         worker's  compensation,  unemployment insurance or similar legislation;
         (xii) any Lien  constituting  a renewal,  extension or replacement of a
         Lien  constituting  a Permitted  Lien, but only if (1) at the time such
         Lien is granted and immediately after giving effect thereto, no Default
         would exist,  (2) such Lien is limited to all or a part of the property
         or asset that was subject to the Lien so renewed,  extended or replaced
         and to fixed improvements thereafter erected on such property or asset,
         (3) the principal  amount of the obligations  secured by such Lien does
         not exceed the principal  amount of the obligation  secured by the Lien
         so renewed,  extended or replaced,  (4) the obligations secured by such
         Lien bear  interest at a rate per annum not exceeding the rate borne by
         the  obligations  secured by the Lien so renewed,  extended or replaced
         except for any increase that is commercially  reasonable at the time of
         such increase and (5) the  principal  amount of the  obligations  has a
         final  maturity  date of, and has a Weighted  Average  Life to Maturity
         equal to or greater than the  Weighted  Average Life to Maturity of the
         obligation secured by the Lien so renewed,  extended or replaced;(xiii)
         any Liens on  Collateral  to the extent  granted  under the  Collateral
         Document;  and  (xiv)  any  Liens  to  the  extent  granted  under  the
         Stockholders Agreement.

         Section 1.16 Sixteenth Definitional Amendment.  The Indenture is hereby
amended to add a new defined term "Security Interest" thereto, as follows:




                      First Supplemental Indenture: Page 7

<PAGE>




                  "Security   Interest"  means  the  security  interest  in  the
         Collateral or any part thereof  granted to the Collateral  Agent by the
         Company  or TTC for the  benefit  of the  Holders  under the  Indenture
         pursuant to the Collateral Document.

         Section  1.17  Seventeenth  Definitional  Amendment.  The  Indenture is
hereby amended to add a new defined term "Stockholders  Agreement"  thereto,  as
follows:

                  "Stockholders  Agreement"  means the  Stockholders  Agreement,
         dated as of May 19, 1999,  by and among Newco,  Newbridge,  TTC and the
         Company.

         Section 1.18 Eighteenth Definitional Amendment. The Indenture is hereby
amended to modify the definition of  "Subsidiary"  to exclude Newco therefrom by
adding a new second sentence to the definition, as follows:

                  "Subsidiary"  means,  with  respect  to any  Person,  (i)  any
         corporation,  association or other  business  entity of which more than
         50% of the  total  voting  power of shares of  Capital  Stock  entitled
         (without  regard to the occurrence of any  contingency)  to vote in the
         election of  directors,  managers  or  trustees  thereof is at the time
         owned or controlled,  directly or indirectly,  by such Person or one or
         more  of the  other  Subsidiaries  of  such  Person  (or a  combination
         thereof) and (ii) any  partnership  (a) the sole general partner or the
         managing  general  partner of which is such Person or a  Subsidiary  of
         such Person or (b) the only  general  partners of which are such Person
         and/or one or more  Subsidiaries  of such  Person  (or any  combination
         thereof).  Notwithstanding  the foregoing,  Newco shall not be deemed a
         "Subsidiary"  of the Company for  purposes  of this  Indenture,  unless
         after the  consummation  of the Newco  Contribution  and the  Newbridge
         Initial  Investment  it shall become a  Wholly-Owned  Subsidiary of the
         Company.

         Section 1.19 Nineteenth Definitional Amendment.  The title of the Notes
is hereby  amended to refer to the Notes as  "13-7/8%  Senior  Secured  Discount
Notes due 2005."

         Section 1.20 Twentieth Definitional Amendment.  The Indenture is hereby
amended to add a new defined term "Supplemental Indenture" thereto, as follows:

                  "Supplemental  Indenture"  means the  Supplemental  Indenture,
         dated May 19, 1999, by and among the Company, TNS, TCC, TeleHub Leasing
         Corporation, and the Trustee.





                      First Supplemental Indenture: Page 8

<PAGE>




         Section 1.21  Twenty-First  Definitional  Amendment.  The  Indenture is
hereby amended to modify the defined term "TNS/TTC Transaction," to provide that
the Newco  Contribution  will constitute a "TTC  Transaction"  and that the term
"TNS/TTC  Transaction"  will no longer apply to TTC or Newco under the Indenture
thereafter, as follows:

                  "TNS/TTC Transaction" means (i) a sale, assignment,  transfer,
         lease  conveyance or other  disposition  of all of the capital stock of
         TNS or all or  substantially  all of the  assets  comprising  TNS's ATM
         Network, and/or (ii) a sale, assignment, transfer, lease, conveyance or
         other  disposition  of  all  of  the  capital  stock  of  TTC or all or
         substantially  all of the assets  comprising  TTC's business;  provided
         that no asset of the Company or any of its Subsidiaries shall have been
         or will be  transferred  or licensed to the  Subsidiary  or business be
         divested by the Company  other than on an arm's length basis and in the
         ordinary  course of business  (other  than in respect of the  Newbridge
         Transaction and any of the transactions  contemplated thereby,  subject
         to Section 4.9 of this Indenture);  provided,  further;  that the Newco
         Contribution  constitutes a "TNS/TTC Transaction" for purposes thereof;
         and  provided,  further,  that  after  the  consummation  of the  Newco
         Contribution  no  subsequent  transaction  by the Company or any of its
         Subsidiaries   or  Affiliates  in  respect  of  the  assets  or  Equity
         Securities  of TTC or Newco will  constitute  a  "TNS/TTC  Transaction"
         unless Newco shall be, immediately prior to the consummation thereof, a
         Wholly-Owned  Subsidiary of the Company;  provided,  however,  that the
         immediately  preceding  proviso  shall not apply to the  provisions  of
         Section 5.1 of the Indenture.


                         ARTICLE 2: COVENANT AMENDMENTS

         Section 2.1 First Covenant  Amendment.  The Indenture is hereby amended
to modify  Section 4.4 thereof,  to add  references  in  paragraphs  (a) and (c)
thereof to the Collateral Document, as follows:

         SECTION 4.4.   Compliance Certificate.

                  (a) The Company shall  deliver to the Trustee,  within 90 days
         after the end of each fiscal year, but not less often than annually, an
         Officers'  Certificate  stating that a review of the  activities of the
         Company and its Subsidiaries  during the preceding fiscal year has been
         made  under the  supervision  of the  signing  Officers  with a view to
         determining  whether each of the Company and its Subsidiaries has kept,
         observed,  performed and fulfilled its obligations under this Indenture
         and the  Collateral  Document,  and  further  stating,  as to each such
         Officer  signing such  certificate,  that to the best of his  knowledge
         each of the Company and its Subsidiaries has kept, observed,  performed
         and fulfilled each and every covenant contained in this







                      First Supplemental Indenture: Page 9

<PAGE>




         Indenture  and the  Collateral  Document,  and is not in default in the
         performance  or  observance  of  any  of  the  terms,   provisions  and
         conditions  hereof or  thereof  (or,  if a Default  or Event of Default
         shall have occurred,  describing all such Defaults or Events of Default
         of which he may  have  knowledge  and what  action  each is  taking  or
         proposes to take with respect thereto).

                  (b)  So   long   as  not   contrary   to  the   then   current
         recommendations   of  the  American   Institute  of  Certified   Public
         Accountants,  the year-end financial  statements  delivered pursuant to
         Section 4.3(a) above shall be accompanied by a written statement of the
         Company's independent certified public accountants (who shall be a firm
         of  established  national  reputation  reasonably  satisfactory  to the
         Trustee) that in making the examination  necessary for certification of
         such financial  statements  nothing has come to their  attention  which
         would  lead them to  believe  that  either  the  Company  or any of its
         Subsidiaries  has violated any  provisions of Article 4, 5 or 6 of this
         Indenture or, if any such violation has occurred, specifying the nature
         and  period  of  existence  thereof,  it  being  understood  that  such
         accountants  shall not be liable  directly or  indirectly to any Person
         for any failure to obtain knowledge of any such violation.

                  (c)  The  Company  will,  so  long  as any of  the  Notes  are
         outstanding,  deliver  to  the  Trustee,  forthwith  upon  any  Officer
         becoming  aware of (i) any Default or Event of Default;  (ii) any event
         of default under any other mortgage,  indenture or instrument  referred
         to in  Section  6.1(5),or  (iii) any other  default or event of default
         under the Collateral Document, an Officers' Certificate specifying such
         Default, Event of Default or other default or event of default and what
         action the Company is taking or proposes to take with respect thereto;

         Section 2.2 Second Covenant Amendment.  The Indenture is hereby amended
to modify  Section 4.8  thereof,  to  increase  the  Company's  ability to incur
indebtedness,  notwithstanding  that the  Company  may not be able to incur such
Indebtedness  under the first  paragraph of Section 4.8,  from $10.0  million to
$30.0  million,  by amending the proviso in clause (iv) thereof to delete "$10.0
million," and insert in its place "$30.0  million," and to limit the use of such
additional borrowing capacity to financing for property,  plant or equipment, as
follows:

         SECTION 4.8.   Limitation on the Incurrence of Indebtedness.

                  The  Company  shall  not,  and  shall  not  permit  any of its
         Subsidiaries to, directly or indirectly,  create, incur, issue, assume,
         guarantee  or  otherwise   become   directly  or   indirectly   liable,
         contingently or otherwise, with respect






                      First Supplemental Indenture: Page 10

<PAGE>




         to (collectively,  "incur") any Indebtedness (including Acquired Debt);
         provided,  however, that, so long as no Default or Event of Default has
         occurred and is  continuing,  the Company and any  Guarantor  may incur
         Indebtedness  (including  Acquired Debt) if the  Consolidated  Leverage
         Ratio is less than or equal to 5.50 to 1.00.

                  The foregoing provisions will not apply to:

                  (i)  the  incurrence  by the  Company  and the  Guarantors  of
         Indebtedness  pursuant  to the Bank  Credit  Facility  in an  aggregate
         principal  amount not to exceed 80% of the Company's  receivables  that
         are less than 60 days past due at any one time outstanding less any Net
         Proceeds of Asset Sales applied to  permanently  reduce the Bank Credit
         Facility pursuant to the provisions described under Section 4.14.

                  (ii)     the incurrence by the Company and its Subsidiaries of
         Existing Indebtedness;

                  (iii) the  incurrence by the Company and its  Subsidiaries  of
         Indebtedness  represented by the Notes,  the  Guarantees,  the Exchange
         Notes and the Guarantees thereunder, and this Indenture;

                  (iv) the incurrence by the Company or any of its  Subsidiaries
         of Indebtedness (A) represented by Capital Lease Obligations,  mortgage
         financings or purchase money obligations, in each case incurred for the
         purpose of financing  all or any part of the purchase  price or cost of
         construction or improvement of property, plant or equipment used in the
         business of the Company or such  Subsidiary or (B) in  connection  with
         the  acquisition  of assets  or a new  Subsidiary;  provided,  that the
         aggregate  principal  amount (or  accreted  value,  as  applicable)  of
         Indebtedness  incurred  pursuant  to clause (A) and (B) of this  clause
         (iv),  together  with  any  other  outstanding   Indebtedness  incurred
         pursuant to this clause (iv),  does not exceed $30.0 million at any one
         time outstanding;  provided further that, of such $30.0 million,  $20.0
         million shall only be available, and used by the Company, for financing
         of acquisitions of property,  plant or equipment;  and provided further
         that, if any such  Indebtedness is or has been refinanced  under clause
         (vi),  the  amount  of  Indebtedness  that may be  incurred  and may be
         outstanding  under this  clause  (iv) shall be reduced by the amount of
         such Permitted Refinancing Debt;

                  (v) the  incurrence of  intercompany  Indebtedness  between or
         among the Company and any of its Wholly  Owned  Subsidiaries;  provided
         that any  subsequent  issuance  or transfer  of Equity  Interests  that
         results in any





                      First Supplemental Indenture: Page 11

<PAGE>




         such  Indebtedness  being held by a Person  other than the Company or a
         Wholly Owned  Subsidiary of the Company,  or any sale or other transfer
         of any such  Indebtedness to a Person that is neither the Company nor a
         Wholly Owned  Subsidiary of the Company,  shall be deemed to constitute
         an incurrence of such  Indebtedness by the Company or such  Subsidiary,
         as the case may be;

                  (vi) the incurrence by the Company or any of its  Subsidiaries
         of Permitted  Refinancing  Debt in exchange for, or the net proceeds of
         which are used to extend, refinance,  renew, replace, defease or refund
         Indebtedness that was permitted by this Indenture to be incurred (other
         than Indebtedness incurred under clause (i) above);

                  (vii) the incurrence by the Company or any of its Subsidiaries
         of Hedging  Obligations  that are incurred for the purpose of fixing or
         hedging   interest   rate  risk  with  respect  to  any  floating  rate
         indebtedness  that is  permitted  by the terms of this  Indenture to be
         outstanding; and

                  (viii) the  incurrence by the Company of  Indebtedness  (other
         than secured  Acquired  Debt) in an aggregate  principal  amount not to
         exceed  1.0  times  the sum of the net cash  proceeds  received  by the
         Company  after the date of this  Indenture  (other  than in  respect of
         Disqualified  Stock) in connection with any Public Offerings;  provided
         that such Indebtedness (i) does not mature prior to the maturity of the
         Notes, (ii) has a Weighted Average Life to Maturity at greater than the
         Notes and (iii) is made expressly subordinated to the Notes.

         Section 2.3 Third Covenant  Amendment . The Indenture is hereby amended
to modify  Section 4.11  thereof,  to authorize the  Newbridge  Transaction,  by
adding a new clause (b) to the last sentence thereof, as follows:

         SECTION 4.11.   Limitation on Transactions with Affiliates.

                  The  Company  shall  not,  and  shall  not  permit  any of its
         Subsidiaries to, directly or indirectly,  make any payment to, or sell,
         lease, transfer or otherwise dispose of any of its properties or assets
         to, or purchase any  property or assets from,  or enter into or make or
         amend  any  transaction,  contract,  agreement,   understanding,  loan,
         advance or guarantee  with, or for the benefit of, any Affiliate  (each
         of  the  foregoing,  an  "Affiliate  Transaction"),   unless  (i)  such
         Affiliate  Transaction  is on terms that are no less  favorable  to the
         Company  or the  relevant  Subsidiary  than  those that would have been
         obtained in a comparable  transaction  (as  determined in good faith by
         the Board of Directors) with an unrelated Person and (ii) the





                      First Supplemental Indenture: Page 12

<PAGE>




         Company  delivers  to the  Trustee  (a) with  respect to any  Affiliate
         Transaction  or  series of  related  Affiliate  Transactions  involving
         aggregate  consideration in excess of $1.0 million, a resolution of the
         Board of  Directors  set forth in an Officers'  Certificate  certifying
         that such Affiliate Transaction complies with clause (i) above and that
         such  Affiliate  Transaction  has been  approved  by a majority  of the
         disinterested members of the Board of Directors and (b) with respect to
         any Affiliate  Transaction or series of related Affiliate  Transactions
         involving aggregate consideration in excess of $5.0 million, an opinion
         as to the fairness to the Holders of such Affiliate  Transaction from a
         financial point of view issued by an unaffiliated accounting, appraisal
         or investment  banking firm of national standing.  Notwithstanding  the
         foregoing,  (a)  transactions  between  or among  the  Company  and its
         Subsidiaries and Restricted Payments and Permitted Investments that are
         permitted  by  the  provisions  under  Section  4.9  hereof,   and  (b)
         transactions  between  the  Company,  TTC  and  Newco  as  part  of the
         Newbridge   Transaction,   including   transactions   pursuant  to  the
         Stockholders  Agreement  as in effect  on the date of the  Supplemental
         Indenture,  in each case  shall not be deemed  Affiliate  Transactions,
         subject to Section 4.9 of this Indenture.

         Section 2.4 Fourth Covenant Amendment.  The Indenture is hereby amended
to modify  Section 4.13  thereof to restrict  TTC's  ability to own,  control or
possess any assets other than certain  Investments in Newco or otherwise  engage
in any type of business  activity,  by adding a new subsection  (b) thereto,  as
follows:

         SECTION 4.13.   Business Activities.

                  (a) The Company shall not,  directly or indirectly,  engage in
         any business other than the Telecommunications Business.

                  (b) Notwithstanding anything to the contrary set forth in this
         Indenture,  (A)  TTC  shall  not  (i) own any  assets  other  than  any
         Investments in Newco permitted hereunder,  (ii) and shall not otherwise
         engage  in  any  type  of   business   activity   or  (iii)  incur  any
         Indebtedness;  and (B) all  Investments in Newco of the Company and its
         Subsidiaries  shall be held  directly by TTC (except for the  temporary
         Investment  to be held by the Company as  described  in the  definition
         herein of "Newbridge Transaction").

         Section 2.5 Fifth Covenant  Amendment.  The Indenture is hereby amended
to modify  Section  4.14  thereof  to require  the  Company,  subsequent  to the
Newbridge Initial  Investment,  to use the net proceeds from any sales of Equity
Interests  of TTC or Newco  held by the  Company or any  Subsidiary  or from any
Newco  Sale/Distribution,  to make an offer to  purchase  Notes  pursuant to the
provisions  of Section  4.14 (and allow the  Company to use  proceeds  remaining
thereafter for working capital and general corporate purposes) by





                      First Supplemental Indenture: Page 13

<PAGE>




amending  the  second  paragraph  of Section  4.14 to add a new second  sentence
thereto, as follows:

         SECTION 4.14.   Asset Sales.

                  The  Company  shall  not,  and  shall  not  permit  any of its
         Subsidiaries to, engage in an Asset Sale unless (i) the Company or such
         Subsidiary,  as the case may be, receives  consideration at the time of
         such Asset Sale at least equal to the fair market value (evidenced by a
         resolution  of  the  Board  of  Directors  set  forth  in an  Officers'
         Certificate delivered to the Trustee) of the assets or Equity Interests
         issued or sold or  otherwise  disposed  of and (ii) at least 80% of the
         consideration therefor received by the Company or such Subsidiary is in
         the  form of Cash  Equivalents;  provided  that the  amount  of (a) any
         liabilities (as shown on the Company's or such Subsidiary's most recent
         balance sheet) of the Company or any Subsidiary  (other than contingent
         liabilities and liabilities that are by their terms subordinated to the
         Notes) that are assumed by the  transferee of any such assets  pursuant
         to a customary  novation  agreement  that  releases the Company or such
         Subsidiary   from  further   liability  and  (b)  any  notes  or  other
         obligations  received  by the  Company  or such  Subsidiary  from  such
         transferee  that  are  immediately  converted  by the  Company  or such
         Subsidiary  into Cash  Equivalents (to the extent of the cash received)
         shall be deemed to be Cash Equivalents for purposes of this provision.

                  Within 270 days after the receipt of any Net Proceeds  from an
         Asset Sale, the Company or such  Subsidiary may apply such Net Proceeds
         (i) to permanently  reduce  borrowings  under the Bank Credit  Facility
         (and to  correspondingly  reduce  commitments  with respect thereto) or
         (ii) to make capital  expenditures or acquire  long-term  assets in the
         same line of business as the Company was engaged  immediately  prior to
         such Asset  Sale or, in the case of a sale of  accounts  receivable  in
         connection with any accounts receivable financing,  for working capital
         purposes. Subsequent to the consummation of the Newco Contribution, the
         Newco Initial Investment and the repayment of Indebtedness described in
         clause (v) of the definition herein of "Newbridge  Transaction," in the
         event  (i) that  the  Company  or any  Subsidiary  sells  or  otherwise
         disposes of any Equity  Interests or other  Investments  in TTC or (ii)
         there shall occur any Newco  Sale/Distribution,  the Company shall with
         the Net Proceeds  derived  therefrom to make offers to Holders of Notes
         consistent  with the Asset Sale Offer  provisions  of this Section 4.14
         and with  Section  3.9;  provided,  however,  that if any Net  Proceeds
         remain after the Company  complies with such Asset Sale Offer provision
         the Company may use such  remaining  proceeds  for working  capital and
         general corporate purposes. Pending the final application of any such






                      First Supplemental Indenture: Page 14

<PAGE>




         Net Proceeds, the Company may temporarily reduce senior indebtedness or
         otherwise invest such Net Proceeds in any manner that is not prohibited
         by this  Indenture.  Any Net  Proceeds  from  Asset  Sales that are not
         applied or invested as provided in the first or second sentence of this
         paragraph  will be deemed to  constitute  "Excess  Proceeds."  When the
         aggregate amount of Excess Proceeds  exceeds $2.0 million,  the Company
         will be  required  to make an offer to all  Holders of Notes (an "Asset
         Sale  Offer") to purchase the maximum  principal  amount at maturity of
         Notes that may be  purchased  out of the Excess  Proceeds,  at an offer
         price  in cash in an  amount  equal  to  101% of the  principal  amount
         thereof,  plus accrued and unpaid interest and Liquidated  Damages,  if
         any,  thereon  (or, in the case of an offer to  purchase  that would be
         consummated  prior to July 31, 2001, at a purchase  price equal to 101%
         of the Accreted Value thereof, plus Liquidated Damages thereon, if any)
         to the date of purchase, in accordance with the procedures set forth in
         this  Indenture.  To the extent that the  aggregate  Accreted  Value of
         Notes tendered  pursuant to an Asset Sale Offer is less than the Excess
         Proceeds, the Company may use any remaining Excess Proceeds for general
         corporate purposes (subject to the restrictions of this Indenture).  If
         the Accreted Value of Notes  surrendered by Holders thereof exceeds the
         amount of Excess  Proceeds,  the Trustee  shall  select the Notes to be
         purchased  on a pro  rata  basis.  Upon  completion  of such  offer  to
         purchase, the amount of Excess Proceeds shall be reset at zero.

                  The  Asset  Sale  Offer  must  be  commenced  within  30  days
         following the Asset Sale or Newco  Sale/Distribution  that triggers the
         Company's  obligation  to make the Asset Sale Offer and remain open for
         at least 30 and not more than 40 days  (unless  required by  applicable
         law).  The Company  shall  comply with the  requirements  of 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
         connection  with the  repurchase  of Notes  pursuant  to an Asset  Sale
         Offer.

         Section 2.6 Sixth Covenant  Amendment.  The Indenture is hereby amended
to modify Section 4.15 thereof, to clarify that the Company will not be required
to make a TNS/TTC Put Option Offer as a result of the Newbridge Transaction,  by
adding a new sixth paragraph thereto, as follows:

         SECTION 4.15.   Change of Control or a TNS/TTC Transaction.

                  Upon the  occurrence  of a Change of  Control,  each Holder of
         Notes will have the right to require the Company to  repurchase  all or
         any part (equal to $1,000 face amount or an integral  multiple thereof)
         of such  Holder's  Notes  pursuant  to the offer  described  below (the
         "Change of Control Offer") at an






                      First Supplemental Indenture: Page 15

<PAGE>




         offer  price in cash equal to 101% of the  aggregate  principal  amount
         thereof,  plus  accrued  and unpaid  interest  and  Liquidated  Damages
         thereon,  if  any,  to the  date  of  repurchase  (or,  in the  case of
         repurchase of Notes prior to July 31, 2001,  at a purchase  price equal
         to 101% of the Accreted Value thereof, plus Liquidated Damages thereon,
         if any, to the date of repurchase) (the "Change of Control Payment"). A
         notice of a Change of Control  Offer  shall be  prepared by the Company
         and shall be mailed by the  Company  with a copy to the  Trustee or, at
         the option of the  Company and at the  expense of the  Company,  by the
         Trustee  within 10 days following a Change of Control to each Holder of
         the Notes and such  Change of  Control  Offer must  remain  open for at
         least 30 and not more than 40 days (unless required by applicable law).

                  Upon the occurrence of a TNS/TTC  Transaction,  if the Company
         does not exercise its right to redeem the Notes  concurrently  with the
         consummation  of the  TNS/TTC  Transaction  or has not made an offer to
         each Holder of Notes to repurchase the Notes at the TNS/TTC Transaction
         Purchase Price  concurrently  with the consummation of such transaction
         in a manner that otherwise  complies with the notice  requirements  and
         clauses  (a) and (b)  below  of this  sentence,  the  Company  shall be
         required to (a)  deposit  with the Trustee  upon  consummation  of such
         transaction  sufficient  monies  to  redeem  in  full  the  Notes,  (b)
         delivered  to the Trustee  with a solvency  opinion  (from a nationally
         recognized  investment bank with expertise in giving solvency opinions)
         dated the date of the consummation of such transaction and stating that
         after giving effect to the  redemption of the Notes the Company will be
         solvent and (c) within ten days of the consummation of such transaction
         make an  offer  (a  "TNS/TTC  Put  Option  Offer")  to each  Holder  to
         repurchase  all or any part (equal to $1,000 face amount or an integral
         multiple  thereof)  of each  Holder's  Notes  at an  offer  price  (the
         "TNS/TTC  Transaction Purchase Price") in cash equal to, at any time on
         or prior to July 31, 2002, the Accreted Value thereof, plus accrued and
         unpaid  interest  and  Liquidated  Damages,  if any  thereon,  and  the
         applicable  Make-  Whole  Premium  and after such date the amount  that
         would be payable to the  Holders  of each Note to be  purchased  if the
         Company on such date were to redeem the Notes (the  "TNS/TTC Put Option
         Payment").  The  Company  shall  have the right to make a  TNS/TTC  Put
         Option  Offer  not  more  than 60 nor  less  than 30 days  prior to the
         consummation of the TNS/TTC Transaction.

                  The notice to each Holder of the Notes shall  state:  (1) that
         the Change of Control  Offer or the TNS/TTC  Put Option  Offer is being
         made pursuant to this Section 4.15 and that all Notes  tendered and not
         withdrawn  will  be  accepted  for  payment;  (2) the  purchase  price,
         separately  stating the amount of any accrued and unpaid  interest  and
         Liquidated Damages, if any,




                      First Supplemental Indenture: Page 16

<PAGE>




         and the purchase date,  which will be no earlier than 30 days nor later
         than 60 days  from the date  such  notice is  mailed  (the  "Change  of
         Control  Payment Date" or the "TNS/TTC Put Option Payment  Date");  (3)
         that any Note not tendered will continue to accrue or accrete interest,
         as the case may be;  (4)  that,  unless  the  Company  defaults  in the
         payment  of the Change of Control  Payment  or the  TNS/TTC  Put Option
         Payment,  all Notes  accepted  for  payment  pursuant  to the Change of
         Control  Offer or the TNS/TTC Put Option  Offer will cease to accrue or
         accrete  interest,  as the case may be,  after the  Change  of  Control
         Payment Date or the TNS/TTC Put Option  Payment Date;  (5) that Holders
         electing  to have any Notes  purchased  pursuant to a Change of Control
         Offer or the TNS/TTC Put Option Offer will be required to surrender the
         Notes,  with the form entitled  "Option of Holder to Elect Purchase" on
         the reverse of the Notes completed,  to the Paying Agent at the address
         specified  in the notice  prior to the close of  business  on the third
         Business  Day  preceding  the  Change of  Control  Payment  Date or the
         TNS/TTC Put Option  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 second  Business Day  preceding the Change
         of Control  Payment  Date or the TNS/TTC  Put Option  Payment  Date,  a
         telegram,  telex,  facsimile  transmission  or letter setting forth the
         name  of the  Holders,  the  principal  amount  at  maturity  of  Notes
         delivered for purchase, and a statement that such Holder is withdrawing
         his election to have such Notes purchased; (7) that Holders whose Notes
         are being  purchased  only in part will be  issued  new Notes  equal in
         principal  amount at maturity to the  unpurchased  portion of the Notes
         surrendered,  which  unpurchased  portion  must be equal to  $1,000  in
         principal amount at maturity or an integral multiple  thereof;  and (8)
         the circumstances and material facts regarding the Change of Control or
         TNS/TTC  Transaction  (including  but not limited to  information  with
         respect to the  historical  consolidated  financial  information of the
         Company and pro forma consolidated financial information of the Company
         after  giving  effect to the Change of Control or TNS/TTC  Transaction,
         information  regarding the Person or Persons acquiring control,  to the
         extent reasonably  available,  and the business plans of such Person or
         Persons  with  respect  to  the  Company,   to  the  extent  reasonably
         available).  The Company  shall  comply with the  requirements  of 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 connection with the repurchase of the Notes in connection
         with a Change of Control or TNS/TTC Transaction.

                  On the  Change of  Control  Payment  Date or the  TNS/TTC  Put
         Option  Payment  Date,  as the case may be, the Company  shall,  to the
         extent  lawful,  (i)  accept  for  payment  Notes or  portions  thereof
         properly  tendered  pursuant to the Change of Control  Offer or TNS/TTC
         Put Option Offer, as the case





                      First Supplemental Indenture: Page 17

<PAGE>




         may  be,  (ii)  deposit  with  the  Paying  Agent,   unless  previously
         deposited,  an amount  equal to the  Change of  Control  Payment or the
         TNS/TTC Put Option Payment, as the case may be, in respect of all Notes
         or  portions  thereof  so  tendered  and (iii)  deliver  or cause to be
         delivered  to the  Trustee  the  Notes  so  accepted  together  with an
         Officers'  Certificate  stating the aggregate  principal  amount of the
         Notes or portions  thereof being  purchased by the Company.  The Paying
         Agent  shall  promptly  mail to each  Holder of Notes so  tendered  the
         Change of Control  Payment or the  TNS/TTC Put Option  Payment,  as the
         case  may  be,  for  such  Notes,   and  the  Trustee  shall   promptly
         authenticate  and mail (or cause to be  transferred  by  book-entry) to
         each  Holder a new Note equal in  principal  amount to any  unpurchased
         portion of the Notes  surrendered,  if any; provided that each such new
         Note will be in a principal amount at maturity of $1,000 or an integral
         multiple  thereof.  Prior  to  complying  with the  provisions  of this
         Section  4.15,  and in any event  within 90 days  following a Change of
         Control,  the Company shall either repay all outstanding Senior Debt of
         the  Company  or  obtain  the  requisite  consents,  if any,  under all
         agreements  governing  outstanding Senior Debt of the Company to permit
         the  repurchase  of Notes  required by this Section  4.15.  The Company
         shall  publicly  announce the results of the Change of Control Offer or
         TNS/TTC  Put  Option  Offer,  as the  case  may  be,  on or as  soon as
         practicable after the Change of Control Payment Date or the TNS/TTC Put
         Option Payment Date, as the case may be.

                  Other than as specifically  provided in this Section 4.15, any
         purchase  pursuant to this Section  4.15 shall be made  pursuant to the
         provisions of Section 3.1 through 3.6 hereof.

                  Notwithstanding  any  provision  herein to the  contrary,  the
         Company  will not be required  to make a TNS/TTC Put Option  Offer as a
         result  of any  of  the  transactions  contemplated  by  the  Newbridge
         Transaction, including without limitation the Newco Contribution.

         Section 2.7 Seventh Covenant Amendment. The Indenture is hereby amended
to modify  Section  6.1  thereof,  to include as an "Event of Default" a default
under the Collateral Document, by adding a new clause (10) thereto, as follows:

         SECTION 6.1.  Events of Default.

                  An "Event of Default" occurs if:

                           (1)  the  Company  defaults  in  the  payment  of the
                  principal  of or  premium,  if any,  on any Note when the same
                  becomes due and payable (upon Stated  Maturity,  acceleration,
                  optional redemption,




                      First Supplemental Indenture: Page 18

<PAGE>




                  required purchase (whether pursuant to  Sections 4.14  or 4.15
                  or otherwise) or otherwise); or

                           (2)  the  Company  defaults  in  the  payment  of  an
                  installment  of interest on, or  Liquidated  Damages,  if any,
                  with  respect to, any of the Notes,  when the same becomes due
                  and payable,  which default continues for a period of 30 days;
                  or

                           (3) the Company  fails to comply with the  provisions
                  described  under  Sections 4.9,  4.14,  4.15,  4.1or Article 5
                  hereof; or

                           (4) the Company or a Guarantor, if applicable,  fails
                  to comply with any of its covenants or agreements contained in
                  the Notes or this Indenture (other than a default specified in
                  clause (1), (2) or (3) above) and such default continues for a
                  period of 30 days after notice of such default  requiring  the
                  Company  to  remedy  the same  shall  have  been  given to the
                  Company; or

                           (5)  a  default  under  any  mortgage,  indenture  or
                  instrument  under  which there may be issued or by which there
                  may  be  secured  or  evidenced  any  Indebtedness  for  money
                  borrowed  by the  Company or any of its  Subsidiaries  (or the
                  payment of which is  guaranteed  by the  Company or any of its
                  Subsidiaries),  whether such  Indebtedness  or  guarantee  now
                  exists, or is created after the date of this Indenture,  which
                  default  (a) is  caused  by  failure  to pay  principal  of or
                  premium, if any, or interest on such Indebtedness prior to the
                  expiration of the grace period  provided in such  Indebtedness
                  (a "Payment  Default") or (b) results in the  acceleration  of
                  such  Indebtedness  prior to its express maturity and, in each
                  case described in clauses (a) and (b) of this  subsection (5),
                  the principal amount of any such  Indebtedness,  together with
                  the  principal  amount of any other  such  Indebtedness  under
                  which  there has been a Payment  Default  or the  maturity  of
                  which has been so  accelerated,  aggregates  $2.0  million  or
                  more; or

                           (6) the Company or any of its  Subsidiaries  fails to
                  pay one or more final  judgments  against  the  Company or any
                  Subsidiary  in an  aggregate  amount in excess of $2.0 million
                  and either (a) any creditor commences enforcement  proceedings
                  upon any such  judgment  or (b) such  judgments  are not paid,
                  discharged  or  stayed  for a period of 60 days from the entry
                  thereof;

                           (7) any of the Guarantees of the Guarantors ceases to
                  be in full  force  and  effect  or any of such  Guarantees  is
                  declared to be





                     First Supplemental Indenture: Page 19

<PAGE>




                  null and void and  unenforceable  or any of such Guarantees is
                  found to be invalid or any Guarantor,  or any Person acting on
                  behalf of a Guarantor, denies such Guarantor's liability under
                  its Guarantee  (other than by reason of release of a Guarantor
                  in accordance with the terms of this Indenture);

                           (8) the Company or any of its Subsidiaries,  pursuant
                  to or within the meaning of any Bankruptcy Law:

                  (i)      commences a voluntary case or proceeding,

                  (ii)  consents to the entry of an order for relief  against it
                  in an involuntary case or proceeding,

                  (iii) consents to the  appointment of a Custodian of it or for
                  all or substantially all of its property,

                  (iv)  makes  a  general  assignment  for  the  benefit  of its
                  creditors, or

                  (v) admits in writing its  inability  to pay debts as the same
                  become due; or

                           (9) a court of competent jurisdiction enters an order
                  or decree under any Bankruptcy Law that:

                           (a) is for relief  against the Company or any of  its
                  Subsidiaries in an involuntary case or proceeding,

                           (b) appoints a Custodian  of the  Company,  or any of
                  its  Subsidiaries,   for  all  or  substantially  all  of  its
                  property,

                           (c) orders the  liquidation  of the Company or any of
                  its  Subsidiaries,  and in each  case,  the  order  or  decree
                  remains unstayed and in effect for 60 days; or

                           (10) there exists any of the following:

                           (a) any  failure  by the  Company  or any  Subsidiary
                  thereof to deposit with the Collateral  Agent under the Pledge
                  Agreement  any Equity  Interest or other  Investment in TTC or
                  Newco held by the Company or any of its  Subsidiaries so as to
                  create a valid first priority  perfected Lien therein;  or the
                  Security Interest in any Collateral is declared to be null and
                  void and unenforceable, is found to be invalid





                      First Supplemental Indenture: Page 20

<PAGE>




                  or  ceases  to be a  first  priority  perfected  Lien  in  the
                  Collateral;  or the Company or any Person  acting on behalf of
                  the Company denies the  enforceability of the Pledge Agreement
                  or the  enforceability or perfection of such Security Interest
                  (other  than,  in  each  case,  by  reason  of  a  release  of
                  Collateral  in  accordance   with  the  terms  of  the  Pledge
                  Agreement and this Indenture);

                           (b) a  default  by  the  Company  or  any  Subsidiary
                  thereof  under  Sections  1, 5(b),  5(c) or 5(d) of the Pledge
                  Agreement; or

                           (c) any  default  by the  Company  or any  Subsidiary
                  thereof  under  the  Collateral  Document  (other  than  as  a
                  consequence of a "Default" or "Event of Default"  described in
                  clauses (1)-(9),  (10)(a) or (10)(b) of this Section 6.1), and
                  such default  remains  continuing  for a period of thirty (30)
                  days  after  notice  of such  default  to the  Company  by the
                  Trustee  or  Collateral  Agent or by Holders of 25% or more of
                  the  aggregate  principal  amount of the Notes shall have been
                  given.

                  The term  "Bankruptcy  Law" means title 11,  U.S.  Code or any
         similar  Federal  or state  law for the  relief  of  debtors.  The term
         "Custodian"  means  any  receiver,  trustee,  assignee,  liquidator  or
         similar official under any Bankruptcy Law.

                  In the case of any Event of Default pursuant to the provisions
         of this  Section  6.1  occurring  by reason of any  willful  action (or
         inaction)  taken (or not  taken) by or on behalf of the  Company or the
         Guarantors  with the intention of avoiding  payment of the premium that
         the Company  would have had to pay if the  Company  then had elected to
         redeem the Notes pursuant to Section 3.7 hereof, an equivalent  premium
         shall also  become  and be  immediately  due and  payable to the extent
         permitted  by law upon the  acceleration  of the Notes.  If an Event of
         Default  occurs prior to July 31, 2002, by reason of any willful action
         (or  inaction)  taken (or not taken) by or on behalf of the  Company or
         the  Guarantors  with the  intention  of avoiding  the  prohibition  on
         redemption of the Notes prior to such date, then the premium  specified
         in this Indenture shall also become  immediately due and payable to the
         extent permitted by law upon the acceleration of the Notes.

         Section 2.8 Eighth Covenant Amendment.  The Indenture is hereby amended
to modify Section 6.3 thereof to add a reference to the  Collateral  Document in
the sixth line of the first paragraph thereof, as follows:

         SECTION 6.3.   Other Remedies.





                      First Supplemental Indenture: Page 21

<PAGE>




                  If an Event of Default occurs and is  continuing,  the Trustee
         may and  shall at the  direction  of the  Holders  of 25% in  principal
         amount at maturity of the then  outstanding  Notes pursue any available
         remedy  (under this  Indenture or  otherwise) to collect the payment of
         principal,  premium,  interest or  Liquidated  Damages,  if any, on the
         Notes or to enforce the performance of any provision of the Notes, this
         Indenture,  the  Registration  Rights  Agreement  and/or the Collateral
         Document.

                  The Trustee and  Collateral  Agent may  maintain a  proceeding
         even if it does not possess any of the Notes or does not produce any of
         them  in  the  proceeding.  A  delay  or  omission  by the  Trustee  or
         Collateral  Agent or any  Holder  of Notes in  exercising  any right or
         remedy  accruing upon an Event of Default shall not impair the right or
         remedy  or  constitute  a waiver  of or  acquiescence  in the  Event of
         Default. All remedies are cumulative to the extent permitted by law.

         Section 2.9  Ninth Covenant Amendment.  The Indenture is hereby amended
to modify Section 7.8 thereof to include references therein  to  the  Collateral
Agent, as follows:

         SECTION 7.8. Replacement of Trustee or Collateral Agent.

                  A resignation  or removal of the Trustee or Collateral  Agent,
         as the case may be, and appointment of a successor Trustee or successor
         Collateral  Agent, as the case may be, shall become effective only upon
         the successor  Trustee's or successor  Collateral  Agent's, as the case
         may be, acceptance of appointment as provided in this Section.

                  The Trustee may resign at any time and be discharged  from the
         trust hereby created,  and the Collateral  Agent may resign at any time
         and be discharged of its  responsibilities  under the Pledge Agreement,
         by so  notifying  the  Company  by at least 30  days'  advance  written
         notice.  The  Holders of a  majority  in  principal  amount of the then
         outstanding  Notes may remove the Trustee or the Collateral  Agent,  as
         the case may be, by so notifying the Trustee or the  Collateral  Agent,
         as the case may be, and the Company in writing.  The Company may remove
         the Trustee or the Collateral Agent, as the case may be, if:

                           (a)  in the case of the Trustee, the Trustee fails to
                  comply with Section  7.10;

                           (b) the Trustee or the Collateral  Agent, as the case
                  may be, is adjudged a bankrupt or an insolvent or an order for
                  relief is







                      First Supplemental Indenture: Page 22

<PAGE>




                  entered with respect to the Trustee or  Collateral  Agent,  as
                  the case may be, under any Bankruptcy Law;

                           (c) a Custodian or public officer takes charge of the
                  Trustee or the Collateral  Agent, as the case may be, or their
                  respective properties; or

                           (d) the Trustee or the Collateral  Agent, as the case
                  may be, becomes incapable of acting.

                  If the Trustee or the  Collateral  Agent,  as the case may be,
         resigns or is  removed or if a vacancy  exists in the office of Trustee
         or the  Collateral  Agent,  as the case  may be,  for any  reason,  the
         Company  shall  promptly  appoint  a  successor  Trustee  or  successor
         Collateral  Agent,  as the  case may be.  Within  one  year  after  the
         successor  Trustee or successor  Collateral  Agent, as the case may be,
         takes office, the Holders of a majority in principal amount of the then
         outstanding   Notes  may  appoint  a  successor  Trustee  or  successor
         Collateral  Agent, as the case may be, to replace the successor Trustee
         or successor  Collateral  Agent,  as the case may be,  appointed by the
         Company.

                  If a successor  Trustee or successor  Collateral Agent, as the
         case may be,  does not take  office  within 60 days after the  retiring
         Trustee or retiring Collateral Agent, as the case may be, resigns or is
         removed, the retiring Trustee or retiring Collateral Agent, as the case
         may be, the Company or the Holders of at least 10% in principal  amount
         of the then  outstanding  Notes may  petition  any  court of  competent
         jurisdiction  for the  appointment of a successor  Trustee or successor
         Collateral Agent, as the case may be.

                  If the Trustee or Collateral  Agent, as the case may be, after
         written  request  by any Holder of Notes who has been a Holder of Notes
         for at least six months fails to comply with Section 7.10,  such Holder
         of Notes may, on behalf of himself and all others  similarly  situated,
         petition  any court of  competent  jurisdiction  for the removal of the
         Trustee or Collateral Agent, as the case may be, and the appointment of
         a successor Trustee or successor Collateral Agent, as the case may be.

                  The  Company  shall  give or cause to be given  notice of each
         resignation and each removal of the Trustee or Collateral Agent, as the
         case may be, to all Holders in the manner provided herein.  Each notice
         shall include the name of the successor Trustee or successor Collateral
         Agent,  as the case may be,  and the  address  of its  Corporate  Trust
         Office.






                      First Supplemental Indenture: Page 23

<PAGE>




                  A successor Trustee or successor Collateral Agent, as the case
         may be, shall deliver a written  acceptance of its  appointment  to the
         retiring Trustee or retiring  Collateral Agent, as the case may be, and
         to the Company.  Thereupon,  the resignation or removal of the retiring
         Trustee or retiring  Collateral Agent, as the case may be, shall become
         effective,  and the successor Trustee or successor Collateral Agent, as
         the  case  may be,  shall,  in the  case of the  Trustee,  have all the
         rights,  powers and duties of the  Trustee  under  this  Indenture  and
         shall, in the case of the Collateral Agent, have all the rights, powers
         and duties of the  Collateral  Agent  under the Pledge  Agreement.  The
         successor  Trustee or successor  Collateral  Agent, as the case may be,
         shall mail a notice of its succession to Holders of Notes. The retiring
         Trustee  or  retiring  Collateral  Agent,  as the  case  may be,  shall
         promptly  transfer  all  property  held by it as Trustee or  Collateral
         Agent,  as the case  may be,  to the  successor  Trustee  or  successor
         Collateral  Agent,  as the  case may be,  provided,  in the case of the
         Trustee,  all sums owing to the  Trustee  hereunder  have been paid and
         subject  to the  Lien  provided  for in  Section  7.7.  Notwithstanding
         replacement  of the Trustee or  Collateral  Agent,  as the case may be,
         pursuant to this Section 7.8, the Company'  obligations  under  Section
         7.7 hereof shall  continue  for the benefit of the retiring  Trustee or
         Collateral Agent, as the case may be. No successor Trustee or successor
         Collateral  Agent,  as the case may be,  shall  accept its  appointment
         unless  at the  time of  such  acceptance  such  successor  Trustee  or
         successor  Collateral Agent, as the case may be, shall be qualified and
         eligible under this Article 7.

         Section 2.10 Tenth Covenant Amendment . The Indenture is hereby amended
to modify Section 7.9 thereof,  to include  references therein to the Collateral
Agent, as follows:

         SECTION 7.9.   Successor Trustee or Collateral Agent by Merger, etc.

                  If the  Trustee  or  Collateral  Agent,  as the  case  may be,
         consolidates,   merges  or  converts   into,   or   transfers   all  or
         substantially   all  of  its  corporate   trust  business  to,  another
         corporation, the successor corporation without any further act shall be
         the successor  Trustee or successor  Collateral  Agent, as the case may
         be; provided that such successor is otherwise eligible hereunder.

         Section  2.11  Eleventh  Covenant  Amendment.  The  Indenture is hereby
amended to modify  Section  9.1  thereof,  to add the phrase "or the  Collateral
Document" in the second line of the first paragraph thereof, as follows:

         SECTION 9.1.   Without Consent of Holders.






                      First Supplemental Indenture: Page 24

<PAGE>




                  The  Company,  the  Guarantors  and the  Trustee  may amend or
         supplement  this  Indenture,  the  Notes,  or the  Collateral  Document
         without the consent of any Holder of Notes:

                  (1) to cure any ambiguity,  defect or inconsistency;  provided
                  that such  amendment or supplement  does not adversely  affect
                  the rights of any Holder;

                  (2) to comply with Article 5;

                  (3) to provide for  uncertificated  Notes in addition to or in
                  place of certificated Notes;

                  (4) to provide for the  assumption  of the  Company's  and the
                  Guarantor's obligations to Holders of the Notes in the case of
                  a merger or consolidation;

                  (5) to provide additional security for the Notes;

                  (6) to add Guarantees with respect to the Notes;

                  (7) to make any  change  that  would  provide  any  additional
                  rights or  benefits  to the  Holders of the Notes or that does
                  not adversely  affect the legal rights hereunder of any Holder
                  of the Notes; or

                  (8) to comply with  requirements of the SEC in order to effect
                  or maintain the qualification of this Indenture under the TIA.

                  Upon the request of the Company,  accompanied  by a resolution
         of the Board of Directors of the Company,  authorizing the execution of
         any such supplemental  indenture or amendment,  and upon receipt by the
         Trustee of the  documents  described in Section 9.6 hereof  required or
         requested  by the Trustee,  the Trustee  shall join with the Company in
         the execution of any supplemental  indenture or amendment authorized or
         permitted  by the  terms  of this  Indenture  and to make  any  further
         appropriate agreements and stipulations which may be therein contained,
         but the Trustee shall not be obligated to enter into such  supplemental
         indenture  or  amendment  which  affects  its  own  rights,  duties  or
         immunities under this Indenture or otherwise.






                     First Supplemental Indenture: Page 25

<PAGE>




         Section  2.12  Twelfth  Covenant  Amendment.  The  Indenture  is hereby
amended to modify  Section 9.2  thereof,  to include  references  therein to the
Collateral Agent and the Collateral Document, as follows:

         SECTION 9.2.   With Consent of Holders.

                  Except as  otherwise  provided  herein,  the  Company  and the
         Trustee may amend or supplement  this  Indenture or the Notes,  and the
         Company and the Collateral Agent may amend or supplement the Collateral
         Document,  in each case with the  written  consent of the Holders of at
         least  a  majority  in  principal   amount  at  maturity  of  the  then
         outstanding Notes (including, without limitation,  consents obtained in
         connection  with a purchase of, or tender  offer or exchange  offer for
         the Notes).

                  Upon the request of the Company,  accompanied  by a resolution
         of the Board of Directors of the Company  authorizing  the execution of
         any such  supplemental  indenture  or  amendment  or  amendment  to the
         Collateral  Document,  and upon the filing with the Trustee of evidence
         satisfactory  to the  Trustee of the consent of the Holders of Notes as
         aforesaid,  and upon receipt by the Trustee of the documents  described
         in Section 9.6 hereof,  in respect of the  Indenture  the Trustee shall
         join with the Company in the execution of such  supplemental  indenture
         or amendment unless such  supplemental  indenture or amendment  affects
         the Trustee's own rights,  duties or immunities under this Indenture or
         otherwise,  in which case the Trustee may in its discretion,  but shall
         not be obligated  to,  enter into such  supplemental  indenture  and in
         respect of the Collateral Document the Collateral Agent shall join with
         the Company in the  execution  of an  amendment  unless such  amendment
         affects the Collateral  Agent's own rights,  duties or immunities under
         the  Collateral  Document or  otherwise,  in which case the  Collateral
         Agent may in its discretion,  but shall not be obligated to, enter into
         such amendment.

                  It shall not be necessary for the consent of the Holders under
         this  Section  9.2 to  approve  the  particular  form  of any  proposed
         supplemental indenture or amendment, but it shall be sufficient if such
         consent approves the substance thereof.

                  After a supplemental indenture or amendment under this Section
         becomes  effective,  the Company shall mail to the Holders of each Note
         affected  thereby a notice briefly  describing the amendment or waiver.
         Any failure of the Company to mail such notice,  or any defect therein,
         shall not,  however,  in any way impair or affect the  validity  of any
         such supplemental  indenture,  amendment or waiver. Subject to Sections
         6.4 and 6.7 hereof, the




                     First Supplemental Indenture: Page 26

<PAGE>




         Holders of a majority in principal amount at maturity of the Notes then
         outstanding  may  waive  compliance  in a  particular  instance  by the
         Company  with any  provision of this  Indenture or the Notes.  However,
         without the consent of each Holder of Notes  affected,  an amendment or
         waiver under this Section may not (with  respect to any Notes held by a
         non-consenting Holder of Notes):

                  (1) reduce the  principal  amount at  maturity  of Notes whose
                  Holders must consent to an amendment, supplement or waiver;

                  (2)  reduce  the rate of or  change  the time for  payment  of
                  interest or  Liquidated  Damages,  if any,  including  default
                  interest, on any Note or change or have the effect of changing
                  the definition of Accreted Value;

                  (3) reduce the  principal  of or change the fixed  maturity of
                  any  Note  or  alter  the  provisions   with  respect  to  the
                  redemption  of the Notes  (other than  provisions  relating to
                  Sections  4.14 and  4.15) or  reduce  the  prices at which the
                  Company  shall  offer  to  purchase  such  Notes  pursuant  to
                  Sections 3.9, 4.14 or 4.15 hereof;

                  (4) make any Note  payable in money  other than that stated in
                  the Note;

                  (5) make any  change in  Section  6.4 or 6.7 hereof or in this
                  sentence of this Section 9.2;

                  (6) waive a Default  or Event of  Default  in the  payment  of
                  principal  or  Accreted  Value  of  or  premium,  interest  or
                  Liquidated Damages, if any, on the Notes (other than a Default
                  in the payment of an amount due as a result of an acceleration
                  if the Holders of Notes rescind such acceleration  pursuant to
                  Section 6.2);

                  (7) waive a redemption payment with respect to any Note (other
                  than a payment required under Section 4.14 or 4.15);

                  (8) release any Guarantor  from any of its  obligations  under
                  its Guarantee or this  Indenture  otherwise than in accordance
                  with the terms of this Indenture; or

                  (9) release any of the Security  Interests  in the  Collateral
                  otherwise  than in  accordance  with the  terms of the  Pledge
                  Agreement and this Indenture.





                      First Supplemental Indenture: Page 27

<PAGE>




         Section 2.13  Thirteenth  Covenant  Amendment.  The Indenture is hereby
amended  to  modify  10.1  thereof,  to  include  references  to the  Collateral
Document, as follows:

         SECTION 10.1.   Unconditional Guarantee.

                  Each Guarantor hereby unconditionally,  jointly and severally,
         guarantees (such guarantee to be referred to herein as the "Guarantee")
         to each Holder of a Note authenticated and delivered by the Trustee and
         to the  Trustee  and its  successors  and  assigns,  the  Notes and the
         Obligations of the Company  hereunder,  thereunder and under the Pledge
         Agreement, and that (without limiting the generality of the foregoing):
         (i) the principal of and interest on the Notes will be promptly paid in
         full when due,  subject  to any  applicable  grace  period,  whether at
         maturity,  by  acceleration  or  otherwise  and interest on the overdue
         principal,  if any, and interest on any interest, to the extent lawful,
         of the Notes and all other obligations of the Company to the Holders or
         the Trustee  hereunder or  thereunder  will be promptly paid in full or
         performed, all in accordance with the terms hereof and thereof; (ii) in
         case of any  extension of time of payment or renewal of any Notes or of
         any such other obligations, the same will be promptly paid in full when
         due or  performed  in  accordance  with the terms of the  extension  or
         renewal,  subject to any  applicable  grace  period,  whether at stated
         maturity, by acceleration or otherwise and (iii) the obligations of the
         Company and its  Subsidiaries  under the  Collateral  Document shall be
         performed in accordance with the terms thereof;  subject,  however,  in
         the case of clauses (i) and (ii) above, to the limitations set forth in
         Section  10.5.  Each  Guarantor  hereby  agrees  that  its  obligations
         hereunder  shall  be  unconditional,   irrespective  of  the  validity,
         regularity  or  enforceability  of the  Notes,  this  Indenture  or the
         Collateral  Document,  as the case may be, the absence of any action to
         enforce the same, any waiver or consent by any Holder of the Notes with
         respect  to any  provisions  hereof or  thereof,  the  recovery  of any
         judgment  against  the  Company,  any action to enforce the same or any
         other  circumstance  which  might  otherwise   constitute  a  legal  or
         equitable  discharge or defense of a guarantor.  Each Guarantor  hereby
         waives diligence, presentment, demand of payment, filing of claims with
         a court in the event of insolvency  or  bankruptcy of the Company,  any
         right to require a  proceeding  first  against  the  Company,  protest,
         notice and all demands  whatsoever  and covenants  that this  Guarantee
         will  not  be  discharged   except  by  complete   performance  of  the
         obligations  contained in the Notes,  this  Indenture,  the  Collateral
         Document and in this  Guarantee.  If any  Noteholder  or the Trustee is
         required  by any  court or  otherwise  to return  to the  Company,  any
         Guarantor,  or any  custodian,  trustee,  liquidator  or other  similar
         official acting in relation to the Company or any Guarantor, any amount
         paid by the Company or any Guarantor to the Trustee or such Noteholder,
         this Guarantee, to the extent theretofore





                      First Supplemental Indenture: Page 28

<PAGE>




         discharged,  shall  be  reinstated  in  full  force  and  effect.  Each
         Guarantor  further agrees that, as between each  Guarantor,  on the one
         hand,  and the Holders  and the  Trustee,  on the other  hand,  (x) the
         maturity of the  obligations  guaranteed  hereby may be  accelerated as
         provided   in   Article  6  for  the   purposes   of  this   Guarantee,
         notwithstanding  any stay,  injunction or other prohibition  preventing
         such acceleration in respect of the obligations  guaranteed hereby, and
         (y) in the event of any acceleration of such obligations as provided in
         Article 6, such  obligations  (whether  or not due and  payable)  shall
         forthwith  become due and payable by each  Guarantor for the purpose of
         this Guarantee.

         Section 2.14  Fourteenth  Covenant  Amendment.  The Indenture is hereby
amended to modify Section 10.5(b) thereof, to exclude the Newbridge  Transaction
from the provisions thereof, as follows:

         SECTION 10.5.   Guarantors May Consolidate, etc. on Certain Terms.

                           (a) Nothing  contained in this Indenture or in any of
                  the  Notes  shall  prevent  any  consolidation  or merger of a
                  Guarantor  with or into the  Company or another  Guarantor  or
                  shall prevent any sale of assets or conveyance of the property
                  of a Guarantor as an entirety or substantially as an entirety,
                  to  the   Company   or  another   Guarantor.   Upon  any  such
                  consolidation, merger, sale or conveyance, the Guarantee given
                  by such Guarantor shall no longer have any force or effect.

                           (b)  Except as set forth in  Articles 4 and 5 hereof,
                  nothing  contained  in this  Indenture  or in any of the Notes
                  shall prevent any  consolidation or merger of a Guarantor with
                  or into a corporation or  corporations  other than the Company
                  or  another  Guarantor  (whether  or not  affiliated  with the
                  Guarantor)  or shall  prevent any sale of assets or conveyance
                  of the property of a Guarantor as an entirety or substantially
                  as an entirety,  to a corporation or  corporations  other than
                  the Company or another  Guarantor  (whether or not  affiliated
                  with the  Guarantor);  provided,  however,  that,  subject  to
                  Sections 10.3 and 10.5(a), immediately after such transaction,
                  and  giving  effect  thereto  such  transaction  does  not (a)
                  violate  any  covenants  set forth  herein or (b) results in a
                  Default  or Event of  Default  under  this  Indenture  that is
                  continuing.  Nothing  in  this  Indenture  shall  prevent  the
                  transfer  of   VASP(TM)-related   assets  or  sale  of  Equity
                  Interests  pursuant to the Newco  Contribution  in  connection
                  with the Newbridge Transaction.





                      First Supplemental Indenture: Page 29

<PAGE>




         Section 2.15 Fifteenth Covenant  Amendment to Indenture.  The Indenture
is hereby amended to add a new Section 12.1 thereto,  which will provide for the
execution  and delivery of the  Collateral  Document,  which will  establish the
means of securing the performance of the Company's  obligations  under the Notes
through a pledge of Investments in TTC by the Company, as follows:

         SECTION 12.1.    Collateral Document.

                  The due and punctual  payment of the principal of and interest
         on the Notes when and as the same shall be due and payable,  whether on
         an interest  payment date, at maturity,  by  acceleration,  repurchase,
         redemption or otherwise,  and interest on the overdue  principal of and
         interest (to the extent permitted by law), if any, on the Notes and the
         performance of all other  obligations of the Company and the Guarantors
         to the  Holders  of Notes  under  this  Indenture,  the  Notes  and the
         Collateral  Document,  according to the terms  hereunder or thereunder,
         shall be secured as  provided  in the  Collateral  Document,  which the
         Company has  entered  into  simultaneously  with the  execution  of the
         Supplemental  Indenture.  Each  Holder  of  Notes,  by  its  acceptance
         thereof,  consents and agrees to the terms of the  Collateral  Document
         (including,   without   limitation,   the   provisions   providing  for
         foreclosure  and release of Collateral) as the same may be in effect or
         (subject to Article 9) may be amended  from time to time in  accordance
         with its terms and authorizes and directs the Collateral Agent to enter
         into  the  Collateral  Document  and to  perform  its  obligations  and
         exercise its rights  thereunder  in accordance  therewith.  The Company
         shall  do or  cause to be done  all  such  acts  and  things  as may be
         necessary  or proper,  or as may be required by the  provisions  of the
         Collateral Document,  to assure and confirm to the Collateral Agent the
         security  interest  in  the  Collateral  contemplated  hereby,  by  the
         Collateral  Document  or  any  part  thereof,  as  from  time  to  time
         constituted,  so as to render the same  available  for the security and
         benefit of this  Indenture,  and of the Notes and  Collateral  Document
         secured thereby, according to the intent and purposes herein expressed.
         The Company shall take,  or shall cause TTC to take,  and, if requested
         by the Collateral  Agent,  shall request Newbridge and/or Newco to take
         (in respect of the  Collateral  consisting  of Equity  Interests of, or
         Investments  in,  Newco),  any and all actions  reasonably  required to
         cause the Collateral  Document to create and maintain,  as security for
         the Obligations of the Company and Guarantors hereunder and thereunder,
         a valid and enforceable first priority perfected Lien in and on all the
         Collateral,  in favor of the  Collateral  Agent for the  benefit of the
         Holders  of Notes,  superior  to and  prior to the  rights of all third
         Persons  and  subject to no other Liens  (other  than  Permitted  Liens
         described in clauses (v) (in respect of statutory obligations),  (viii)
         and (xiv) of the definition of Permitted Liens).





                      First Supplemental Indenture: Page 30

<PAGE>




         Section 2.16  Sixteenth  Covenant  Amendment . The  Indenture is hereby
amended to add a new  Section  12.2  thereto,  which will  require an opinion of
Company's  counsel as to  creation  and  maintenance  of the  Security  Interest
effected by the Collateral Document, as follows:

         SECTION 12.2.   Recording and Opinions.

                           (a) The Company shall furnish to the Collateral Agent
                  simultaneously   with  the   execution  and  delivery  of  the
                  Supplemental  Indenture  an  Opinion  of  Counsel,  which  may
                  contain customary qualifications,  stating that in the opinion
                  of such  counsel  (i) the  Collateral  Document  has been duly
                  executed and delivered by the Company and TTC and  constitutes
                  the legal,  valid and binding  obligations  of the Company and
                  TTC enforceable against the Company and TTC in accordance with
                  its terms, (ii) the Security Interests purportedly granted and
                  created  by the  Company  and TTC are  valid  and  enforceable
                  security   interests  in  the  Collateral   described  in  the
                  Collateral  Document for the benefit of the Holders under this
                  Indenture, and (iii) with respect to the Security Interests in
                  the Collateral,  all action has been taken with respect to the
                  recording,  registering and filing of the Collateral Document,
                  financing  statements or other  instruments  necessary to make
                  effective  the first  priority  perfected  Lien intended to be
                  created by the  Collateral  Document,  and the details of such
                  action.

                           (b)  The  Company  shall  furnish  to the  Collateral
                  Agent,   simultaneously   with  the  pledge  and  delivery  as
                  additional  Collateral  under the  Collateral  Document of any
                  Investments (or evidences  thereof) made by the Company or any
                  Subsidiary in TTC or Newco after the date of the  Supplemental
                  Indenture (1) in the event that such Subsidiary is not already
                  a party to the Collateral Document,  an instrument  reasonably
                  satisfactory to the Collateral  Agent by which such Subsidiary
                  shall agree to become an additional  "Pledgor"  party thereto,
                  and (2) an Opinion of  Counsel,  which may  contain  customary
                  qualifications,  stating  that in the opinion of such  counsel
                  (i) if  applicable,  the  Collateral  Document  has been  duly
                  executed and delivered by such  Subsidiary and constitutes the
                  legal,   valid  and  binding  obligation  of  such  Subsidiary
                  enforceable  against such  Subsidiary in  accordance  with its
                  terms,  (ii) the Security  Interests  purportedly  granted and
                  created  by such  Pledgor  are  validly  created  and  binding
                  security  interests  in such  Investments  for the  benefit of
                  Holders  under this  Indenture,  and (iii) with respect to the
                  Security  Interests in such  Investments,  all action has been
                  taken with respect




                      First Supplemental Indenture: Page 31

<PAGE>




                  to the  recording,  registering  and filing of the  Collateral
                  Document,  financing statements or other instruments necessary
                  to make effect the first  priority  perfected Lien intended to
                  be created by the Collateral Document in such Investments, and
                  the details of such action.

                           (c) The Company shall furnish to the Collateral Agent
                  on May 31 in each year  beginning with May 31, 1999 an Opinion
                  of  Counsel,  dated as of such date,  either  (i) (A)  stating
                  that,  in the  opinion  of such  counsel,  all action has been
                  taken as is necessary to maintain the first priority perfected
                  status of the Lien of the Collateral Document and reciting the
                  details  of such  action or  referring  to prior  Opinions  of
                  Counsel  in which  such  details  are  given  and (B) based on
                  relevant  laws as in  effect  on the date of such  Opinion  of
                  Counsel, all financing statements and continuation  statements
                  have been  executed  and filed that are  necessary  as of such
                  date and during the succeeding 12 months fully to preserve and
                  protect,  to the extent such protection and  preservation  are
                  possible by filing, the rights of the Holders of Notes and the
                  Collateral  Agent hereunder and under the Collateral  Document
                  with respect to the Security  Interests in the Collateral,  or
                  (ii) stating  that,  in the opinion of such  counsel,  no such
                  action is  necessary  to  maintain  such  Lien and such  first
                  priority perfected status.

         Section 2.17 Seventeenth  Covenant  Amendment.  The Indenture is hereby
amended to add a new Section 12.3  thereto,  which will  establish  the means by
which the Security Interest may be released, as follows:

         SECTION 12.3.   Release of Collateral.

                           (a) Subject to  subsections  (b), (d) and (e) of this
                  Section  12.3,  Collateral  may be released  from the Lien and
                  Security  Interest  created by the Collateral  Document at any
                  time or from time to time in accordance with the provisions of
                  the  Collateral  Document  and as  provided  hereby.  Upon the
                  request of the Company  pursuant to an  Officers'  Certificate
                  certifying and Opinion of Counsel  opining that all conditions
                  precedent  hereunder have been met and stating  whether or not
                  such  release  is in  connection  with an Asset  Sale or Newco
                  Sale/Distribution,  the Collateral Agent shall release (at the
                  sole cost and  expense  of the  Company)  Collateral  which is
                  sold,   conveyed  or  disposed  of  in  compliance   with  the
                  provisions of this Indenture.  Without limiting the generality
                  of the  foregoing,  if such sale,  conveyance  or  disposition
                  constitutes an Asset Sale or Newco




                      First Supplemental Indenture: Page 32

<PAGE>




                  Sale/Distribution, the Company shall apply the Net Proceeds in
                  accordance  with Section 4.14.  Upon receipt of such Officers'
                  Certificate and Opinion of Counsel, the Collateral Agent shall
                  execute,  deliver  or  acknowledge  any  necessary  or  proper
                  instruments  of   termination,   satisfaction  or  release  to
                  evidence  the  release  of  any  Collateral  permitted  to  be
                  released   pursuant  to  this  Indenture  and  the  Collateral
                  Document.

                           (b) The Company may at any time after the date hereof
                  transfer,  assign,  sell or otherwise dispose of any or all of
                  the  Collateral;  provided  that  (i) no  Default  or Event of
                  Default  shall have  occurred and be continuing or would occur
                  as a consequence thereof, (ii) without limiting the generality
                  of the  foregoing,  such transfer,  assignment,  sale or other
                  disposition  (as the case may be) shall be in compliance  with
                  Section  4.14 and  (iii) the  Company  must give ten (10) days
                  prior notice to Collateral Agent of the terms,  conditions and
                  proposed  date of such  transfer,  assignment,  sale or  other
                  disposition  (as the case may be). In such  event,  Collateral
                  Agent shall (a) make  available  to the Company at the closing
                  of such transfer,  assignment,  sale or other  disposition (as
                  the  case may be)  certificates  representing  the  Collateral
                  proposed  to be  sold in such  transfer,  assignment,  sale or
                  other  disposition  (as the case may be);  and (b) release the
                  Security  Interest in such Collateral  against delivery of the
                  proceeds  from  such  transfer,   assignment,  sale  or  other
                  disposition  (as the case  may be)  (net of the  out-of-pocket
                  costs incurred in connection  with such transfer,  assignment,
                  sale or other  disposition (as the case may be)). The proceeds
                  of any such transfer,  assignment,  sale or other  disposition
                  (as the case may be) shall be  immediately  transferred to the
                  Pledge  Account  (as  defined  in  the  Collateral  Document).
                  Promptly  (but in any case  within 30 days)  after  receipt of
                  such  proceeds,  the Company shall make an offer to Holders of
                  Notes to  purchase  the Notes  consistent  with the Asset Sale
                  Offer  provisions  of Section 4.14 of this  Indenture.  If any
                  proceeds  remain after  compliance  with such Asset Sale Offer
                  provisions,  the Collateral Agent shall transfer such proceeds
                  to the  Company,  which may use such  remaining  proceeds  for
                  working capital and general corporate purposes.

                           (c)  Except  to  the  extent  that  any  Lien  on the
                  proceeds of Collateral is automatically  released by operation
                  of  Section  9-306  of the  Uniform  Commercial  Code or other
                  similar law, no Collateral shall be released from the Lien and
                  Security Interest created by the




                      First Supplemental Indenture: Page 33

<PAGE>




                  Collateral   Document   pursuant  to  the  provisions  of  the
                  Collateral  Document unless in compliance with Section 12.3(a)
                  and (b).

                           (d) Notwithstanding  anything in the Indenture or the
                  Collateral  Document  to  the  contrary,  at any  time  when a
                  Default or an Event of  Default  shall  have  occurred  and be
                  continuing,  no Collateral shall be released from the Lien and
                  Security Interest pursuant to the provisions of the Collateral
                  Document,  and no release of  Collateral in  contravention  of
                  this Section 11.3(d) shall be effective as against the Holders
                  of Notes.

                           (e) The release of any Collateral  from the Liens and
                  Security   Interests   created  by  this   Indenture  and  the
                  Collateral Document shall not be deemed to impair the security
                  under this Indenture in contravention of the provisions hereof
                  if and to the extent the  Collateral  is released  pursuant to
                  the  terms   hereof  or,   subject  to   complying   with  the
                  requirements  of this Section  12.3,  pursuant to the terms of
                  the Collateral Document. To the extent applicable, the Company
                  shall  cause  TIA  ss.  314(d),  relating  to the  release  of
                  property or securities from the Lien and Security  Interest of
                  the  Collateral  Document  and  relating  to the  substitution
                  therefor of any property or  securities to be subjected to the
                  Lien and Security Interest of the Collateral  Document,  to be
                  complied with. Any certificate or opinion  required by TIA ss.
                  314(d)  may be made by an  Officer  of the  Company  except in
                  cases where TIA ss. 314(d)  requires that such  certificate or
                  opinion be made by an independent  Person,  which Person shall
                  be an  independent,  appraiser  or other  expert  selected  or
                  approved by the Collateral Agent in the exercise of reasonable
                  care.

         Section 2.18  Eighteenth  Covenant  Amendment.  The Indenture is hereby
amended to add a new Section 12.4 thereto,  which will require  compliance  with
the reporting provisions of the Trust Indenture Act of 1939, as follows:

         SECTION 12.4.   Certificates of the Company.

         The  Company  shall  furnish  to the  Collateral  Agent,  prior to each
         proposed release of Collateral pursuant to the Collateral Document, (i)
         all documents required by Section 314(d) of the TIA, (ii) an Opinion of
         Counsel, to the effect that such accompanying  documents constitute all
         documents required by Section 314(d) of the TIA and (iii) an Opinion of
         Counsel  and  Officer's  Certificate  to the  effect  that the  release
         complies with the  requirements  of the  Indenture  and the  Collateral
         Document. The Collateral Agent may, to the






                      First Supplemental Indenture: Page 34

<PAGE>




         extent  permitted by Sections 7.1 and 7.2 hereof,  accept as conclusive
         evidence of compliance  with the foregoing  provisions the  appropriate
         statements  contained in such documents and such Opinion of Counsel and
         Officer's Certificate.

         Section 2.19  Nineteenth  Covenant  Amendment.  The Indenture is hereby
amended to add a new Section  12.5  thereto,  which will  permit the  Collateral
Agent to take actions that it deems  necessary or appropriate in connection with
the Collateral Document, as follows:

         SECTION 12.5.  Authorization  of Actions to be Taken by the  Collateral
         Agent Under the Collateral Document.

                  Subject to the  provisions of Section 7.1 and 7.2 hereof,  the
         Collateral Agent may, in its sole discretion and without the consent of
         the  Holders  of Notes,  on behalf of the  Holders  of Notes,  take all
         actions it deems  necessary or  appropriate in order to (a) enforce any
         of the terms of the Collateral Document and (b) collect and receive any
         and all amounts  payable in respect of the  Obligations  of the Company
         and Guarantors  hereunder and  thereunder.  The Collateral  Agent shall
         have the power to institute and maintain such suits and  proceedings as
         it may deem  expedient to prevent any  impairment of the  Collateral by
         any  acts  that  may be  unlawful  or in  violation  of the  Collateral
         Document  or this  Indenture,  and such  suits and  proceedings  as the
         Collateral  Agent  may  deem  expedient  to  preserve  or  protect  its
         interests and the  interests of the Holders of Notes in the  Collateral
         (including  power to institute  and maintain  suits or  proceedings  to
         restrain the enforcement of or compliance with any legislative or other
         governmental  enactment,  rule or order that may be unconstitutional or
         otherwise  invalid if the  enforcement  of, or  compliance  with,  such
         enactment,  rule or order would impair the security interest  hereunder
         or be  prejudicial  to the  interests of the Holders of Notes or of the
         Collateral Agent).

         Section 2.20  Twentieth  Covenant  Amendment.  The  Indenture is hereby
amended to add a new Section 12.6 thereto,  relating to  termination of Security
Interest granted under the Collateral Document, as follows:

         SECTION 12.6.   Termination of Security Interest.

                  Upon (a) the payment in full of all Obligations of the Company
         and  Guarantors  under this  Indenture and the Notes and the Collateral
         Document,  or (b) the sale of all the  Collateral  pursuant  to Section
         12.3(b) and the  consummation  of the offer to purchase  Notes acquired
         under Section 4.14 in connection therewith, the Collateral Agent shall,
         at the  request  of the  Company,  and after  receipt  of an  Officers'
         Certificate and Opinion of






                     First Supplemental Indenture: Page 35

<PAGE>




         Counsel  stating  that  all  conditions  to  release  set  forth in the
         Indenture and the Collateral  Document have been met, release the Liens
         pursuant to this Indenture and the Collateral Document.

         Section 2.21 Twenty-first  Covenant Amendment.  The Indenture is hereby
amended to amend the form of Note to  eliminate  the  reference  in  Paragraph 4
thereof to the Notes as  "unsecured"  general  obligations  of the  Company,  as
follows:

         4. Indenture. The Company issued the Notes under an Indenture, dated as
of July 30, 1998 (the  "Indenture"),  among the Company,  the Guarantors and the
Trustee.  Capitalized  terms herein are used as defined in the Indenture  unless
otherwise  defined  herein.  The terms of the Notes  include those stated in the
Indenture  and  those  made  part of the  Indenture  by  reference  to the Trust
Indenture Act of 1939 (15 U.S. Code ss.ss. 77aaa-77bbb) as in effect on the date
of the Indenture. Notwithstanding anything to the contrary herein, the Notes are
subject to all such terms,  and Holders are referred to the  Indenture  and such
Act for a statement of such terms.  The Notes are senior general  obligations of
the Company,  secured to the extent provided in Article 12 of the Indenture, and
limited to  $125,000,000  aggregate  principal  amount at  maturity  (subject to
Section 2.7 of the Indenture).


                       ARTICLE 3: NOTIFICATION OF HOLDERS

         Section 3.1  Notification of Holders.  The Company shall notify Holders
in  accordance  with  Section  9.2 of the  Indenture  of the  execution  of this
Supplement.  Any  failure  of the  Company  to mail such  notice,  or any defect
therein,  shall not,  however,  in any way impair or affect the validity of this
Supplement.


                            ARTICLE 4: MISCELLANEOUS

         Section 4.1 Notices.  Any notice or communication  by the Company,  the
Guarantors  or the  Trustee  to the  others  is duly  given  if in  writing  and
delivered by hand delivery, by first-class mail (registered or certified, return
receipt requested),  by facsimile or by overnight air courier  guaranteeing next
day delivery, to the others' addresses as follows:

If to the Company or any Guarantor:

                  TeleHub Communications Corporation
                  1175 Tristate Parkway
                  Gurnee, Illinois 60031
                  Attention: Chief Financial Officer
                  Telecopier No: [(847) 623-1616]










                      First Supplemental Indenture: Page 36

<PAGE>


If to the Trustee:

                  State Street Bank and Trust Company
                  Two International Place-4th Floor
                  Boston, MA 02110
                  Attention: Corporate Trust Division:
                  TeleHub Communications Corporation--
                  13-7/8% Senior Discount Notes due 2005
                  Telecopier No.: (617) 664-5151

         The Company,  the  Guarantors or the Trustee,  by notice to the others,
may  designate  additional  or  different  addresses  of  subsequent  notices or
communications.

         All  notices  and  communications  (other than those sent to Holders of
Notes)  shall be deemed to have been duly  received:  at the time  delivered  by
hand, if personally  delivered;  five Business Days after being deposited in the
mail,  postage  prepaid,  if  mailed;  when  receipt  is  confirmed,  if sent by
facsimile;  and the next Business Day after timely  delivery to the courier,  if
sent by overnight air courier guaranteeing next day delivery.

         Any  notice or  communication  to a Holder of Notes  shall be mailed by
first-class mail, certified or registered requested, to his address shown on the
register kept by the Registrar.  Failure to mail a notice or  communication to a
Holder of Notes or any  defect  in it shall  not  affect  its  sufficiency  with
respect to other Holders of Notes.

         If a notice or  communication  is mailed in the manner  provided  above
within the time  prescribed,  it is duly  given,  whether  or not the  addressee
receives it.

         If the Company mails a notice or  communication to Holders of Notes, it
shall mail a copy to the Trustee and each Agent at the same time.

         Section 4.2       Governing Law.  THIS SUPPLEMENT SHALL BE GOVERNED
BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF
NEW YORK, AS APPLIED TO CONTRACTS MADE AND PERFORMED  ENTIRELY  WITHIN THE STATE
OF NEW YORK,  WITHOUT  REGARD TO  PRINCIPLES  OF CONFLICT  OF LAWS.  EACH OF THE
PARTIES HERETO AGREES TO SUBMIT TO THE TO THE  JURISDICTION OF THE COURTS OF THE
STATE OF NEW YORK IN ANY ACTION OR PROCEEDING ARISING OUT OF OR RELATING TO THIS
SUPPLEMENT.

         Section  4.3  No  Adverse  Interpretation  of  Other  Agreements.  This
Supplement  may  not be  used  to  interpret  another  indenture,  loan  or debt
agreement of the Company or its Subsidiaries.  Any such indenture,  loan or debt
agreement may not be used to interpret this Supplement.






                      First Supplemental Indenture: Page 37

<PAGE>




         Section  4.4  Successors.   All  agreements  of  the  Company  in  this
Supplement  shall bind its  successor.  All  agreements  of the  Trustee in this
Supplement shall bind its successor.

         Section 4.5 Severability.  In case any one or more of the provisions in
this  Supplement  shall  be  held  invalid,  illegal  or  unenforceable  in  any
jurisdiction,  in any  respect  for  any  reason,  the  validity,  legality  and
enforceability  of any such provision in every other  jurisdiction  and in every
other respect, and of the remaining provisions, shall not in any way be affected
or impaired  thereby,  it being intended that all of the provisions hereof shall
be enforceable to the full extent permitted by law.

         Section 4.6 Counterpart  Originals.  This Supplement may be executed in
any number of counterparts, each of which shall be deemed to be an original, but
all of them together shall represent the same agreement.

         Section 4.7 Table of  Contents,  Headings,  etc. The Table of Contents,
Cross-  Reference  Table and  Headings  of the  Articles  and  Sections  of this
Supplement  have been inserted for  convenience of reference only, are not to be
considered a part hereof and shall in no way modify or restrict any of the terms
or provisions hereof.

         Section 4.8 Indenture.  Except as amended hereby, the Indenture and the
Notes are in all  respects  ratified  and  confirmed  and all their  terms shall
remain in full  force and  effect.  From and  after  the  effectiveness  of this
Supplement,  any  reference  to the  Indenture  or to the Notes  shall  mean the
Indenture or the Notes,  as the case may be, as so amended by this Supplement or
the Notes, as the case may be, as so amended by this Supplement.

         Section 4.9 Effectiveness.  The provisions of this Supplement will take
effect  immediately upon its execution and delivery by the Trustee in accordance
with the provisions of Section 9.2 of the Indenture.

                      [signatures appear on following page]


















                      First Supplemental Indenture: Page 38

<PAGE>




                  IN  WITNESS   WHEREOF,   the  undersigned   have  caused  this
Supplement to be executed as of the date first above written.

                               TELEHUB COMMUNICATIONS CORPORATION


                               By:___________________________________________
                                        Donald H. Sledge
                                        President and Chief Executive Officer


                               TELEHUB NETWORK SERVICES CORPORATION


                               By:___________________________________________
                                        Donald H. Sledge
                                        Chairman

                               TELEHUB TECHNOLOGIES CORPORATION


                               By:___________________________________________
                                        Donald H. Sledge
                                        Chairman


                               TELEHUB LEASING CORPORATION


                               By:___________________________________________
                                        Donald H. Sledge
                                        Chairman


                               STATE STREET BANK AND TRUST COMPANY,
                               as trustee

                               By:___________________________________________
                                        Chi Ma
                                        Assistant Vice President




                                                                     EXHIBIT 4.6




                                PLEDGE AGREEMENT

         PLEDGE AGREEMENT ("Pledge Agreement"), dated as of May 19, 1999, by and
among TELEHUB COMMUNICATIONS  CORPORATION, a Nevada corporation ("TCC"), TELEHUB
TECHNOLOGIES  CORPORATION,  a Nevada corporation  (("TTC, and together with TCC,
collectively,  the "Pledgors"), and STATE STREET BANK AND TRUST COMPANY ("SSB"),
as collateral agent (the "Collateral  Agent"),  for the holders of the Notes (as
defined herein).

                              W I T N E S S E T H:

         WHEREAS,  TCC,  TeleHub  Network  Services  Corporation,   an  Illinois
corporation,  TTC, TeleHub Leasing Corporation, a Nevada corporation and SSB, as
Trustee (the "Parties"),  are a party to that certain Indenture dated as of July
30, 1998 (as amended, restated,  supplemented or otherwise modified from time to
time,  the  "Indenture"),  pursuant to which TCC issued  $125,000,000  aggregate
principal amount of 13-7/8% Senior Discount Notes due 2005 (the "Notes");

         WHEREAS, on the date hereof, TCC is the sole legal and beneficial owner
of certain  shares of common  stock of TTC, as more  particularly  described  in
Exhibit A hereto (the ("TTC Pledged Securities");

         WHEREAS,  on the date hereof,  TTC is the legal and beneficial owner of
certain shares of common stock of Terabridge  Corporation,  a Nevada corporation
(("Newco"),  as more  particularly  described  in Exhibit B hereto (the  ("Newco
Pledged   Securities,"   and,   together   with  the  TTC  Pledged   Securities,
collectively, the ("Pledged Securities");

         WHEREAS, the TTC Pledged Securities represent, on the date hereof, 100%
of the  outstanding  shares  of  Capital  Stock  of TTC  and the  Newco  Pledged
Securities  represent,  on the date  hereof,  81% of the  outstanding  shares of
Capital Stock of Newco;

         WHEREAS,  the  Parties,  on the  date  hereof,  are  entering  into the
Supplemental Indenture,  and in connection therewith,  the Pledgors are required
to execute and deliver this Pledge Agreement; and

         WHEREAS,  to secure the payment  and  performance  by TCC,  TTC and the
other Guarantors of their respective obligations under the Indenture,  the Notes
and this Pledge Agreement (collectively,  the "Obligations"),  including without
limitation,  the due and  punctual  payment of  principal of and interest on the
Notes  when and as the same  shall be due and  payable  whether  on an  interest
payment date, at maturity, by acceleration, repurchase, redemption or otherwise,
and on overdue  principal of and interest on the Notes, the Pledgors have agreed
to place the Pledged  Securities in the Pledge Account (as defined herein) to be
held by the Collateral Agent for the ratable benefit of Holders of the Notes and
to pledge  and grant to the  Collateral  Agent for the  ratable  benefit  of the
Holders of the Notes a  security  interest  in the  Pledged  Securities  and the
Pledge Account and to execute and deliver this Pledge Agreement.








                                       1
<PAGE>

         NOW, THEREFORE,  Pledgors and Collateral Agent, intending legally to be
bound, hereby agree as follows:

     1.  Pledge and Grant of Security Interest.

         (a) The Pledgors hereby pledge and deliver to the Collateral  Agent for
the  ratable  benefit  of the  Holders of the  Notes,  and  hereby  grant to the
Collateral  Agent  for  the  ratable  benefit  of the  Holders  of the  Notes  a
continuing first priority  security interest in and to, (i) all of the Pledgors'
rights,  title and  interest  in, to and under the  Pledged  Securities  and the
Pledge  Account,   (ii)  all   certificates  or  other  evidences  of  ownership
representing the Pledged Securities  (including one or more undated stock powers
executed  in blank by the  appropriate  Pledgor),  and  (iii) all  products  and
proceeds of any of the Pledged  Securities  and/or  Pledged  Account,  including
without limitation, all dividends,  interest, principal payments, cash, options,
warrants, rights, instruments, subscriptions and other property or proceeds from
time to time received,  receivable or otherwise  distributed or distributable in
respect of or in exchange for any or all of the Pledged Securities (the "Initial
Collateral")  and  collectively,  with  any  additional  Collateral  pledged  or
required  to be pledged  under  Section  1(b),  and the  products  and  proceeds
thereof, the "Collateral").

         (b) If either Pledgor or any other Subsidiary of the Company shall make
any additional  Investments in Newco, at any time or from time to time after the
date hereof,  such Pledgor or Subsidiary as the case may be, will  forthwith (i)
pledge and deposit such Investments as additional  Collateral hereunder with the
Collateral  Agent and  deliver to the  Collateral  Agent  certificates  therefor
accompanied  by  undated  stock or bond  powers  duly  executed  in blank by the
appropriate Pledgor or Subsidiary, as the case may be, or such other instruments
of  transfer  as are  acceptable  to the  Collateral  Agent,  and will  promptly
thereafter deliver to the Collateral Agent a certificate  executed by any of the
President,  any  Vice  President,  or  the  Treasurer  of  TCC  describing  such
Investments  and  certifying  that  the  same has  been  duly  pledged  with the
Collateral  Agent  hereunder and (ii) take such other and further actions as may
be required under the terms of the Indenture in connection therewith.

         (c) This Pledge Agreement and the Collateral secure the Obligations.

     2.  Delivery of  Collateral;  Pledge  Account;  Interest;  Substitution  of
Collateral; Release of Collateral.

         (a) All  certificates  or  instruments  representing  or evidencing any
Collateral  shall be  delivered  to and held by or on behalf  of the  Collateral
Agent  pursuant  hereto and shall be in suitable form for transfer and delivery,
and shall be accompanied by undated instruments of transfer or assignment,  duly
executed in blank,  all in form and  substance  satisfactory  to the  Collateral
Agent.

         (b)  Concurrent   with  the  execution  and  delivery  of  this  Pledge
Agreement,  the  Collateral  Agent  shall  establish  an  account  entitled  the
("TELEHUB  PLEDGE  ACCOUNT"  for the  deposit  of the  Collateral  (the  "Pledge
Account") at its office at Two International Place, Boston, Massachusetts 02110.
Subject to the other terms and conditions of this Pledge Agreement, all funds or
other  property  accepted  by the  Collateral  Agent  pursuant  to  this  Pledge
Agreement  shall be held in the Pledge  Account for the  ratable  benefit of the
Holders of the Notes,  and any  proceeds  of or  constituting  Collateral  shall
remain on deposit in the Pledge Account until  withdrawn in accordance with this
Pledge Agreement.






                                       2
<PAGE>


         (c) All stock dividends and other securities  issued with respect to or
otherwise  constituting  Collateral  shall be retained in the Pledge Account and
shall be accompanied by an instrument of transfer contemplated by Section 2(a).

         (d) All  interest on or other cash  dividends  paid with respect to any
Collateral shall be paid over to and retained by the appropriate Pledgor subject
to compliance with Section 4.14 of the Indenture.

         (e) Pledgors  shall have the right at any time after the date hereof to
transfer,  assign,  sell or otherwise dispose of any or all of the Collateral (a
"Collateral Sale");  provided that (i) no Default or Event of Default shall have
occurred  and be  continuing  or shall occur as a result  thereof,  (ii) without
limiting the  generality  of the  foregoing,  such  Collateral  Sale shall be in
compliance  with  the  Asset  Sale  Offer  provisions  of  Section  4.14  of the
Indenture,  and (iii)  Pledgors shall give ten (10) days prior written notice to
Collateral  Agent of the terms,  conditions and proposed date of such Collateral
Sale. In such event,  the Collateral  Agent shall (i) make available to Pledgors
at the closing of such Collateral Sale certificates  representing the Collateral
proposed to be sold in such  Collateral  Sale;  and (ii)  release  the  Security
Interest  in  such  Collateral  against  delivery  of  the  proceeds  from  such
Collateral Sale (net of the out-of-pocket costs incurred in connection with such
Collateral  Sale). The proceeds of any such Collateral Sale shall be immediately
transferred  to the Pledge  Account.  Promptly  (but in any case within 30 days)
after  receipt of such  proceeds,  the  Company  shall make offers to Holders of
Notes  consistent  with the Asset Sale Offer  provisions  of Section 4.14 of the
Indenture.  If any proceeds  remain after  compliance with such Asset Sale Offer
provisions,  the  Collateral  Agent shall transfer such proceeds to the Company,
which may use such remaining  proceeds for working capital and general corporate
purposes.

     3.  Representations  and Warranties.  The Pledgors,  jointly and severally,
hereby represent and warrant that:

         (a) The  execution,  delivery and  performance  by the Pledgors of this
Pledge  Agreement  has  been  duly  authorized  by the  Pledgors  and  does  not
contravene  or  constitute  a default  under any  provision of  applicable  law,
regulation  or the  certificate  of  incorporation  or  bylaws  of either of the
Pledgors,  or of  any  judgment,  injunction,  order,  decree  or  any  material
agreement or instrument  binding upon the  Pledgors,  and does not result in the
creation of imposition of any Lien on any asset of the Pledgors,  except for the
security interests granted under this Pledge Agreement.

         (b) No financing  statement  covering any  Collateral is on file in any
public  office,  other than financing  statements  filed pursuant to this Pledge
Agreement.

         (c) The  pledge  of the  Initial  Collateral  pursuant  to this  Pledge
Agreement  constitutes,  and upon the  delivery to the  Collateral  Agent of the
certificates,  or other  evidences,  of any additional  Collateral  constituting
("securities"  under the Uniform  Commercial  Code  (("UCC"),  and the filing of
financing  statements  required  by the UCC with  respect  to  other  additional
Collateral the pledge of such other Collateral pursuant to this Pledge Agreement
will constitute,  a valid and perfected first priority  security interest in and
to the  Collateral,  securing the payment and performance of the Obligations for
the ratable benefit of the Holders of the Notes, enforceable as such against all
creditors  of the  Pledgors  and any persons  purporting  to purchase any of the
Collateral from the Pledgors.






                                       3
<PAGE>


         (d) No  consent  of any other  Person  and no  consent,  authorization,
approval,  or other action by, and no notice to or filing with, any governmental
authority  or  regulatory  body,  is  required  either (i) for the pledge by the
Pledgors  of the  Collateral  pursuant  to  this  Pledge  Agreement  or for  the
execution,  delivery or performance of this Pledge  Agreement by the Pledgors or
(ii) for the exercise by the Collateral Agent of the rights provided for in this
Pledge Agreement of the remedies in respect of the Collateral  pursuant to or in
connection with this Pledge Agreement.

         (e) The pledge of the Collateral  pursuant to this Pledge  Agreement is
not  prohibited  by  any  applicable  law  or  government  regulation,  release,
interpretation  or  opinion of the Board of  Governors  of the  Federal  Reserve
System or other regulatory agency (including, without limitation, Regulations G,
T, U and X of the Board of Governors of the Federal Reserve System).

         (f) The statements  made in the six "Whereas"  clauses  hereinabove are
true, correct and complete.

         (g) Except for the  Stockholders  Agreement (as defined below), a true,
correct and complete copy of which has been delivered to the Collateral Agent on
or prior to the date hereof,  there is no agreement or  instrument  binding upon
the Collateral Agent (including,  without limitation, the charter and by-laws of
Newco) that  restricts  or  purports  to  restrict  the ability and power of the
Collateral  Agent hereunder from taking  ownership and control of any Collateral
or  from  effecting  a  Disposition  thereof  (as  defined  in the  Stockholders
Agreement).

     4. Further  Assurances.  The Pledgors agree to promptly take such other and
further  actions  and to  execute  and  deliver  or  cause  to be  executed  and
delivered,  such other and further stock or bond powers,  proxies,  assignments,
instruments  and  writings,  as the  Collateral  Agent  may  from  time  to time
reasonably  request,  all in form and substance  satisfactory  to the Collateral
Agent,  deliver  any  instruments  to the  Collateral  Agent  and take any other
actions that are  necessary  to perfect,  continue the  perfection  of,  confirm
evidence,  and/or assure the first priority of the Collateral  Agent's  security
interest in the Collateral, to protect the Collateral against the rights, claims
or interests  of third  Persons,  and/or or to otherwise  effect the purposes of
this Pledge Agreement. Notwithstanding the foregoing, the Collateral Agent shall
have no duty or  obligation  to ensure  the  maintenance  or  perfection  of any
security interest hereunder.

     5.  Covenants.  The Pledgors,  jointly and severally,  hereby  covenant and
agree with the Collateral  Agent for the benefit of the Holders of the Notes, as
follows:

         (a) The  Pledgors  (i) will not create or permit to exist any Lien upon
or with respect to any of the Collateral,  except for the Liens created pursuant
to this  Pledge  Agreement,  and (ii) will at all times be the sole  record  and
beneficial owner of the Collateral.

         (b) The  Pledgors  will not (i) enter into,  approve or permit to exist
any agreement,  instrument or understanding  (including without limitation,  the
charter and by-laws of Newco,  but excluding the  Stockholders  Agreement)  that
purports to or may restrict or inhibit the Collateral Agent's rights or remedies
hereunder,  including,  without limitation, the Collateral Agent's right to sell
or otherwise  Dispose of the Collateral,  or (ii) with regard to the Collateral,
fail to pay or discharge any tax,  assessment or levy of any nature then due and
payable  with  respect  thereto  later  than five days  prior to the date of any
proposed sale under any judgment, writ or warrant of attachment.





                                       4
<PAGE>


         (c) The  Pledgors  will not (I) amend or permit the  amendment  of that
certain Stockholders Agreement, dated May 19, 1999, by and among TTC, Newco, and
Newbridge Networks  Corporation (the ("Stockholders  Agreement"),  in any manner
which  would  actually  or in effect  (A) amend  Section  14.24  thereof  or (B)
otherwise materially adversely affect (i) the Collateral Agent's ability to sell
or otherwise  Dispose of any of the Collateral under this Pledge Agreement or to
otherwise  exercise  its rights and  remedies  hereunder,  (ii) the ability of a
purchaser of any Collateral in any sale  contemplated or permitted under Section
10 to acquire the  unencumbered  title  thereto  subject only to, in the case of
Newco Pledged  Securities or other Equity  Interests in Newco,  (x) Stockholders
Agreement  restrictions on transfer in effect on the date hereof (as affected by
Section 14.24  thereof),  and (y) other  Stockholder  Agreement  provisions  not
prohibited  hereunder,  or (iii) the payment or funding  requirements  and other
liabilities and obligations of the Collateral Agent or any such purchaser as the
direct or indirect transferee,  successor and/or assign of TTC; or (II) take any
action,  or  otherwise  permit  to  exist  any  other  agreement  or  instrument
(including,  without  limitation,  the charter and by-laws of Newco) having that
purpose or effect.

         (d) The Pledgors will provide the  Collateral  Agent with a copy of any
notice delivered to or by either of the Pledgors under Sections 5, 7, 9 or 13 or
after a Default  or Event of  Default  shall have  occurred  and be  continuing,
Sections 2.3 or 3 of the Stockholders  Agreement,  within five (5) business days
of the delivery of any such notice.

      6. Power of Attorney.

         (a) Each Pledgor hereby  constitutes and appoints the Collateral  Agent
as such Pledgor's agent and attorney-in-fact to exercise,  to the fullest extent
permitted  by law,  all of the  following  powers upon and at any time after the
occurrence  and during the  continuance of an Event of Default or upon Pledgors'
failure to take any of the following actions:

           (i)    collection of proceeds of any Collateral;

           (ii)   conveyance of any item of Collateral to any purchaser  thereof
                  as specified herein;

           (iii)  giving of any notices or  recording  of any Liens  pursuant to
                  Sections 1, 2 or 4 hereof;

           (iv)   taking any other  acts  required  to be taken by the  Pledgors
                  pursuant to this Pledge Agreement; and

           (v)    paying or discharging taxes or Liens levied or placed upon the
                  Collateral,  the legality or validity  thereof and the amounts
                  necessary  to  discharge  the  same  to be  determined  by the
                  Collateral Agent in its sole discretion, and any such payments
                  made by the Collateral  Agent shall become  Obligations of the
                  Pledgors to the Collateral Agent, due and payable  immediately
                  upon demand.







                                       5
<PAGE>


         (b)  The  Collateral  Agent's  authority  under  this  Section  6 shall
include,  without limitation,  the authority to endorse and negotiate any checks
or instruments representing proceeds of Collateral in the names of the Pledgors,
execute and give  receipt  for any  certificate  of  ownership  or any  document
constituting Collateral, transfer title to any item of Collateral, to the extent
permitted by applicable law, sign the Pledgors' names on all stock powers,  bond
powers, or other instruments of assignment or transfer,  financing statements or
any other documents  deemed  necessary or appropriate by the Collateral Agent to
preserve,  process or perfect the security  interest in the  Collateral,  and to
file the  same,  and to  prepare,  sign the names of the  Pledgors  and file any
notice of Lien,  and to take any other  actions  arising from or incident to the
powers granted to the Collateral Agent in this Pledge  Agreement.  This power of
attorney is coupled with an interest and shall be irrevocable by the Pledgors.

     7.  Collateral  Agent May  Perform.  If the  Pledgors  fail to perform  any
agreement contained herein, the Collateral Agent may, but shall not be obligated
to,  itself  perform  or cause  performance  of such  agreement  (as  agent  and
attorney-in-fact  under  Section  6  hereof,  or  otherwise),  and the  expenses
incurred by or on behalf of the Collateral  Agent in connection  therewith shall
be payable by the Pledgors under Section 10 hereof.


     8. No Assumption of Duties;  Reasonable Care. The rights and powers granted
to the  Collateral  Agent  hereunder  are being granted in order to preserve and
protect the security interest of the Collateral Agent for the ratable benefit of
the Holders of Notes in and to the  Collateral  granted  hereby and shall not be
interpreted to, and shall not, impose any duties on the Collateral Agent or such
holders in connection therewith.


     9. Indemnity.  The Pledgors shall pay to the Collateral  Agent from time to
time  reasonable  compensation  for its acceptance of this Pledge  Agreement and
services hereunder.  Except as otherwise expressly provided herein, the Pledgors
shall  reimburse the  Collateral  Agent promptly upon request for all reasonable
disbursements,  advances and expenses  incurred or made by it in addition to the
compensation  for its services in  accordance  with any provision of this Pledge
Agreement (including, without limitation, the reasonable compensation,  expenses
and  disbursements  of its  counsel  and of all  agents  and other  persons  not
regularly in its employ (A) in connection  with the  preparation,  execution and
delivery  of this  Pledge  Agreement,  any  waiver  or  consent  hereunder,  any
modification or termination  hereof, or any Event of Default or alleged Event of
Default;  (B) if an Event of Default  occurs,  in connection  with such Event of
Default and collection, bankruptcy, insolvency and other enforcement proceedings
relating  thereto;  (C) in connection with the  administration of the Collateral
Agent's rights  pursuant  hereto;  or (D) in connection  with any removal of the
Collateral  Agent,  except such  disbursements,  advances and expenses as may be
attributable to its gross negligence or bad faith.

         The Pledgors shall  indemnify the Collateral  Agent against any and all
losses, liabilities, obligations, damages, penalties, judgments, actions, suits,
proceedings,  reasonable  costs  and  expenses  (including  reasonable  fees and
disbursements  of counsel) of any kind  whatsoever  which may be incurred by the
Collateral  Agent  in  connection  with  any  investigative,  administrative  or
judicial proceeding (whether or not such indemnified party is designated a party
to such  proceeding)  arising out of or in  connection  with the  acceptance  or
administration  of its duties under this Pledge  Agreement;  PROVIDED,  HOWEVER,
that the Pledgors need not reimburse any expense or indemnify  against any loss,







                                       6
<PAGE>


obligation, damage, penalty, judgment, action, suit, proceeding, reasonable cost
or expense (including  reasonable fees and disbursements of counsel) of any kind
whatsoever  which may be incurred by the Collateral Agent in connection with any
investigative,  administrative  or  judicial  proceeding  (whether  or not  such
indemnified  party  is  designated  a party to such  proceeding)  in which it is
determined that the Collateral Agent acted with gross  negligence,  bad faith or
willful  misconduct.  The Collateral Agent shall notify the Pledgors promptly of
any claim for which it may seek indemnity. Failure by the Collateral Agent to so
notify  the  Pledgors  shall  not  relieve  the  Pledgors  of  their  respective
obligations  hereunder.  The Pledgors  shall defend the claim and the Collateral
Agent shall  cooperate in the defense.  Unless  otherwise set forth herein,  the
Collateral  Agent  may have  separate  counsel  and the  Pledgors  shall pay the
reasonable  fees and  expenses of such  counsel.  Pledgors  need not pay for any
settlement  made without its consent,  which consent  shall not be  unreasonably
withheld.

         The  obligations  of the Company under this Section 9 shall survive the
satisfaction and discharge of this Pledge Agreement.

         When the Collateral Agreement incurs expenses or renders services after
an Event of Default,  the  expenses  and the  compensation  for the services are
intended  to  constitute   expenses  of  administration   under  any  applicable
Bankruptcy Law.

     10. Remedies upon Event of Default.

         (a) Upon the  occurrence of a ("Default"  or ("Event of Default"  under
the  Indenture,  including as a result of a default by the  Pledgors  under this
Pledge Agreement (as further  described in Sections  6.1(10)(a),  (b) and (c) of
the Indenture),  the Collateral Agent shall have and may exercise with reference
to the Collateral any or all of the rights and remedies of a secured party under
the UCC in effect in the Commonwealth of Massachusetts, and as otherwise granted
herein or under any other applicable law,  including,  without  limitation,  the
right  and  power to sell,  at public or  private  sale or sales,  or  otherwise
dispose of, or otherwise  utilize the  Collateral and any part or parts thereof,
in any manner  authorized or permitted under said UCC after default by a debtor,
and to apply the proceeds  thereof  toward payment of any costs and expenses and
attorneys' fees and expenses thereby incurred by the Collateral Agent and toward
payment of the  Obligations in such order or manner as the Collateral  Agent may
elect.  Specifically,  and without limiting the foregoing,  the Collateral Agent
shall have the right to take  possession of all or any part of the Collateral or
any security  therefor and of all books,  records,  papers and  documents of the
Pledgors or in the Pledgors'  possession or control  relating to the  Collateral
that are not already in the Collateral Agent's possession,  and for such purpose
may enter upon any  premises  upon which any of the  Collateral  or any security
therefor or any of said books,  records,  papers and  documents are situated and
remove the same therefore  without any liability for trespass or damages thereby
occasioned.  The Collateral  Agent shall give Pledgors  twenty (20) days notice,
given in the manner  provided  in Section 16 hereof  before the time of any such
sale or disposition.  Pledgors agree that such notice shall be deemed reasonable
and  shall  fully  satisfy  any  requirement  for  giving  of said  notice.  The
Collateral  Agent  shall  not be  obligated  to  make  any  sale  of  Collateral
regardless of notice of sale having been given. The Collateral Agent may adjourn
any public or private sale. The Pledgors  further agree to use their  respective
best  efforts to do or cause to be done all such other acts as may be  necessary
to effect the intention of this Section 10.






                                       7

<PAGE>


         (b) All rights to marshalling of assets of the Pledgors,  including any
such right with respect to the  Collateral,  are hereby  waived by the Pledgors.
The  Pledgors  shall not contest or support any other person in  contesting  the
validity  or  priority  of the  security  interests  created  under this  Pledge
Agreement.

     11.  Fees  and  Expenses.  The  Pledgors  shall,  upon  demand,  pay to the
Collateral Agent the amount of the fees (which shall be in an amount  previously
agreed by the  Pledgors  and the  Collateral  Agent) and any and all  reasonable
expenses  (including,  without  limitation,  the reasonable  fees,  expenses and
disbursements of counsel,  experts and agents retained by the Collateral  Agent)
that the Collateral Agent may incur in connection with (i) the administration of
this  Pledge  Agreement,  (ii) the custody or  preservation  of, or the sale of,
collection  from, or other  realization  upon, any of the Collateral,  (iii) the
exercise or  enforcement  of any of the rights of the  Collateral  Agent and the
holders of the Notes  hereunder,  or (iv) the failure by the Pledgors to perform
or observe any of the provisions hereof.


     12. Security Interest Absolute.  All rights of the Collateral Agent and the
holders of the Notes,  and the security  interests  created  hereunder,  and all
obligations  of the  Pledgors  hereunder,  shall be absolute  and  unconditional
irrespective of any:

         (a) invalidity or unenforceability  of the Indenture,  the Supplemental
Indenture,  the  Notes,  any  of  the  Guarantees,  or any  other  agreement  or
instrument relating thereto;

         (b) change in the time,  manner or place of payment of, or in any other
term of, all or any of the  Obligations,  or any other amendment or waiver of or
any consent to any departure from the Indenture or Notes;

         (c) exchange,  surrender, release or non-perfection of any Liens on any
other  collateral  for  all  or any of the  Obligations  or any  release  of any
Guarantor; or

         (d)  other  action,   event  or  circumstances   that  might  otherwise
constitute a defense  available  to, or a discharge  of,  Pledgors in respect to
Obligations or of this Pledge Agreement.

     13. Continuing Security Interest; Termination.

         (a) This Pledge  Agreement  shall  create a first  priority  continuing
security interest in and to the Collateral and shall,  unless otherwise provided
in the Indenture or in this Pledge  Agreement,  be released (i) upon the payment
in full of all Obligations due and owing or (ii) to the extent of any Collateral
Sale in compliance  with Section 2(e).  This Pledge  Agreement  shall be binding
upon the Pledgors,  their  respective  successors and assigns,  and shall inure,
together with the rights and remedies of the Collateral Agent hereunder,  to the
benefit  of the  Collateral  Agent  and  the  holders  of the  Notes  and  their
respective successors, transferees and assigns.

         (b) This  Pledge  Agreement  shall  terminate  upon the  earlier of (i)
payment  in full in cash of all  Obligations;  and  (ii)  the sale of all of the
Collateral  pursuant to a Collateral  Sale in  compliance  with Section 2(e). At
such time, the Collateral  Agent shall,  at the written request of the Pledgors,
reassign and redeliver to the Pledgors all of the Collateral  hereunder that has
not been sold,  disposed  of,  retained  or applied by the  Collateral  Agent in
accordance  with the terms of this  Pledge  Agreement  and the  Indenture.  Such
reassignment  and  redelivery  shall be  without  warranty  (either  express  or
implied) by or recourse to the Collateral Agent, except as to the absence of any
prior assignments by the Collateral Agent of its interest in the Collateral, and
shall be at the expense of the Pledgors.






                                       8
<PAGE>


     14. Authority of the Collateral Agent.

         (a) The  Collateral  Agent shall have and be  entitled to exercise  all
powers  hereunder that are  specifically  granted to the Collateral Agent by the
terms hereof,  together with such powers as are reasonably incident thereto. The
Collateral  Agent may perform any of its duties  hereunder or in connection with
the Collateral by or through agents or employees and shall be entitled to retain
counsel and to act in reliance  upon the advice of counsel  concerning  all such
matters. None of the Collateral Agent, any director, officer, employee, attorney
or agent of the Collateral Agent nor the holders of the Notes shall be liable to
the  Pledgors  for any action taken or omitted to be taken by Pledgors or either
of them hereunder, except for Pledgors' or their own bad faith, gross negligence
or willful  misconduct,  nor shall the Collateral  Agent be responsible  for the
validity,  effectiveness  or  sufficiency  hereof or of any document or security
furnished  pursuant hereto.  The Collateral  Agent and its directors,  officers,
employees,  attorneys and agents shall be entitled to rely on any communication,
instrument  or document  believed by it or them to be genuine and correct and to
have been signed or sent by the proper Person or Persons.

         (b) The Pledgors  acknowledge that the rights and  responsibilities  of
the  Collateral  Agent under this Pledge  Agreement  with  respect to any action
taken by the Collateral  Agent or the exercise or non-exercise by the Collateral
Agent of any option, right, request,  judgment or other right or remedy provided
for herein or  resulting  or arising  out of this  Pledge  Agreement  shall,  as
between the  Collateral  Agent and the holders of the Notes,  be governed by the
Indenture and by such other  agreements  with respect  thereto as may exist from
time to time among them, but, as between the Collateral  Agent and the Pledgors,
the Collateral  Agent shall be  conclusively  presumed to be acting as agent for
the holders of the Notes with full and valid authority so to act or refrain from
acting,  and the Pledgors shall not be obligated or entitled to make any inquiry
respecting such authority.

         (c) The  Collateral  Agent  undertakes  to perform such duties and only
such  duties as are  specifically  set  forth in this  Pledge  Agreement  and no
implied  covenants  or  obligations  shall be read  into this  Pledge  Agreement
against the Collateral  Agent.  The Collateral Agent shall not be deemed to have
knowledge of an Event of Default under the Indenture  unless informed in writing
by a Pledgor or the Holder of any Note.

         (d)  Collateral  Agent shall not be required to exercise  any  remedies
hereunder  unless  requested in writing to do so by the holders of a majority in
principal  amount of the outstanding  Notes and only if furnished with indemnity
satisfactory to the Collateral Agent.  Collateral Agent may consult with counsel
and shall not be liable for any  action  taken in good  faith in  reliance  upon
advice of  counsel,  except  for gross  negligence  or willful  misconduct.  The
Collateral  Agent  makes  no  representation  or  warranty  and  shall  have  no
responsibility  concerning  the  value  or  validity  of the  Collateral  or the
validity or perfection of the pledge thereof.

         (e) The Collateral  Agent shall be deemed to have exercised  reasonable
care in the custody and  preservation of the Collateral in its possession if the
Collateral is accorded treatment  substantially  equal to that which an ordinary
person accords its own property, it being understood that neither the Collateral
Agent  nor  the  holders  of  the  Notes  shall  have   responsibility  for  (i)
ascertaining  or taking  action with respect to calls,  conversions,  exchanges,
maturities,  tenders or other matters relative to any Collateral, whether or not
any such  Person has or is deemed to have  knowledge  of such  matters,  or (ii)
taking any necessary  steps to preserve  rights against any parties with respect
to any Collateral.





                                       9

<PAGE>


        (f) Any resignation or removal of the Collateral  Agent and appointment
of a successor  Collateral  Agent shall become effective only in accordance with
the provisions of Section 7.8 of the Indenture.

     15.  Notices.  Any  communication,  notice or demand to be given  hereunder
shall be duly given  hereunder  if given in the form and manner  required by the
Indenture,  and  delivered  to  any  recipient's  address  as set  forth  in the
Indenture, or in such other form and manner or to such other address as shall be
designated  by any party hereto to each other party  hereto in a written  notice
delivered in accordance with the terms of the Indenture.


     16. No Waiver;  Cumulative Rights. No failure on the part of the Collateral
Agent  to  exercise  and no delay  in  exercising  any  right,  remedy  or power
hereunder  shall  operate as a waiver  thereof,  nor shall any single or partial
exercise  by the  Collateral  Agent or any  right,  remedy  or  power  hereunder
preclude any other or future exercise of any other right,  remedy or power. Each
and every right,  remedy and power  hereby  granted to the  Collateral  Agent or
allowed it by law under this Pledge Agreement or under any other agreement shall
be cumulative  and not exclusive,  and may be exercised by the Collateral  Agent
from time to time.

     17. Benefits of Pledge Agreement.

         Nothing in this Pledge  Agreement,  whether  express or implied,  shall
give to any Person other than the parties hereto and their successors hereunder,
and the  holders of the Notes,  any  benefit  or any legal or  equitable  right,
remedy or claim under this Pledge Agreement.

     18.  Voting.  Unless  and until a Default  or Event of  Default  shall have
occurred and be  continuing,  the Pledgors shall be entitled to vote any and all
Pledged  Securities and to give consents,  waivers or  ratifications  in respect
thereof,  provided  that  no  vote  shall  be cast  or any  consent,  waiver  or
ratification  given or any action taken which would  violate or be  inconsistent
with any of the terms of this Pledge  Agreement.  In the event that a Default or
Event of Default shall have occurred and be  continuing,  all such rights of the
Pledgors to vote and to give consents,  waivers and  ratifications  shall cease,
and shall be exercisable exclusively by the Collateral Agent.


     19. Applicable Law; Consent to Jurisdiction; Waiver of Jury Trial.

         (a) THIS PLEDGE AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES
HEREUNDER  SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE  WITH, THE INTERNAL
LAWS OF THE STATE OF NEW YORK. TO INDUCE THE COLLATERAL AGENT TO ENTER INTO THIS
PLEDGE AGREEMENT,  THE PLEDGORS HEREBY  IRREVOCABLY  AGREE THAT,  SUBJECT TO THE
COLLATERAL AGENT'S SOLE AND ABSOLUTE  ELECTION,  ALL ACTIONS OR PROCEEDINGS THAT








                                       10
<PAGE>


IN ANY MANNER  ARISE OUT OF OR IN  CONNECTION  WITH OR ARE IN ANY WAY RELATED TO
THIS PLEDGE  AGREEMENT SHALL BE LITIGATED IN COURTS LOCATED WITHIN THE COUNTY OF
NEW YORK,  STATE OF NEW YORK. THE PLEDGORS HEREBY CONSENT TO THE JURISDICTION OF
ANY STATE OR FEDERAL COURT LOCATED  WITHIN THE COUNTY OF NEW YORK,  STATE OF NEW
YORK. THE PLEDGORS HEREBY  IRREVOCABLY  CONSENT TO THE SERVICE OF PROCESS OF ANY
OF THE AFOREMENTIONED  COURTS IN ANY SUCH ACTION OR PROCEEDING BY THE MAILING OF
COPIES THEREOF BY REGISTERED OR CERTIFIED  MAIL TO THE PLEDGORS'  NOTICE ADDRESS
SPECIFIED HEREIN.  THE PLEDGORS HEREBY WAIVE ANY RIGHT THEY MAY HAVE TO TRANSFER
OR CHANGE THE VENUE OF ANY  LITIGATION  BETWEEN THE  PLEDGOR AND THE  COLLATERAL
AGENT IN ACCORDANCE WITH THIS PARAGRAPH. EACH OF THE PLEDGORS AND THE COLLATERAL
AGENT HEREBY KNOWINGLY,  VOLUNTARILY AND INTENTIONALLY WAIVES ANY RIGHT TO TRIAL
BY JURY IN ANY  ACTION OR  PROCEEDING  THAT IN ANY  MANNER  ARISES  OUT OF OR IN
CONNECTION WITH OR IS IN ANY WAY RELATED TO THIS PLEDGE  AGREEMENT OR ANY OF THE
TRANSACTIONS CONTEMPLATED HEREIN.


         (b) THE PROVISIONS OF THIS SECTION 19 ARE A MATERIAL INDUCEMENT FOR THE
COLLATERAL  AGENT  ENTERING  INTO THIS  PLEDGE  AGREEMENT  AND THE  TRANSACTIONS
CONTEMPLATED HEREBY. THE PLEDGORS HEREBY ACKNOWLEDGE THAT THEY HAVE REVIEWED THE
PROVISIONS OF THIS SECTION 19 WITH INDEPENDENT COUNSEL.

     20. Execution in Counterparts. This Pledge Agreement may be executed in any
number  of  counterparts,   each  of  which  shall  be  an  original,  but  such
counterparts shall together constitute one and the same instrument.

     21.  Settlement.  Amounts,  if any,  held  in the  Pledge  Account  pending
settlement of purchase of the Pledged  Securities  shall  constitute  Collateral
hereunder,  shall be held by the Collateral Agent for the benefit of the Holders
of the Notes and a portion  thereof equal to the  aggregate  price paid for such
Pledged  Securities  shall be released by the Collateral  Agent (without further
direction or instruction  required from any other party hereto) against delivery
of such Pledged Securities, and any excess funds remaining in the Pledge Account
after  giving  effect to such  settlement  shall be  promptly  forwarded  to the
Pledgors.

     22. Defined Terms.  Capitalized terms used but not otherwise defined herein
shall have the meanings given to such terms in the Indenture.









                                       11
<PAGE>


                             Stock Pledge Agreement
         IN WITNESS  WHEREOF,  the  parties  hereto  have  executed  this Pledge
Agreement as of the date first above written.


                               TELEHUB COMMUNICATIONS CORPORATION


                                 By:_________________________________________
                                    John R. Lawson, Chief Financial Officer



                               TELEHUB TECHNOLOGIES CORPORATION


                                 By:_________________________________________
                                    John A. Strand, III, President



                               STATE STREET BANK AND TRUST COMPANY,
                                    as Collateral Agent


                                 By:___________________________________________
                                    Chi Ma
                                    Assistant Vice President



                                                                    EXHIBIT 99.4


Newbridge Networks and TeleHub Technologies  Complete Joint Venture;  TeraBridge
Technologies is Officially Formed

May 25, 1999 9:13 AM EDT
New Company Makes Network Convergence a Reality;  Call-Control  Software Enables
Switched Voice and Data Over a Single On-Demand Network

GURNEE,  Ill.,  May 25  /PRNewswire/  -- To meet the  growing  demand  for high-
bandwidth, switched voice and data over a single network architecture, Newbridge
Networks (NYSE: NN; Toronto:  NNC) and TeleHub  Technologies  have announced the
completion of the new joint venture company, TeraBridge Technologies. TeraBridge
will market a Virtual Access Services Platform (VASP(TM)), commercially known as
PathMinder(TM), a suite of software-based intelligent call control products that
provide a graceful  migration  path from  narrowband  circuit  switching to next
generation,  on-demand broadband  networks.  The software enables voice and data
service   convergence  over  an  integrated  and  flexible   broadband   network
architecture while protecting  service provider  investment in legacy narrowband
circuit switches.

"We are quite  pleased that the joint venture has been  consummated  so quickly.
Newbridge Networks,  leaders of the ATM-switch market, and TeleHub's vision of a
software driven network, come to fruition through this joint venture," said John
Strand, president and COO of TeraBridge. "Adding our software capabilities turns
an ATM  switch  from a piece of  hardware  into a service  platform  capable  of
providing a new generation of integrated, on- demand services."

When combined with an ATM switch,  PathMinder(TM)  is the first service  control
platform capable of provisioning, managing, monitoring and billing voice or data
calls -- from dial tone to  termination  -- over a public  or  private  switched
network.  Running in parallel with any transport network,  PathMinder offers the
capabilities  of a  facilities-based  network  on  a  virtual  basis,  providing
narrowband-to-broadband  interworking to dynamically  allocate  bandwidth across
any multiservice network.

The PathMinder software collects the necessary information from Signaling System
7 (SS7)  and  standard  broadband  interfaces  to set up  calls  across  any ATM
network,  as well as send  necessary  provisioning  and  connection  commands to
various  network  elements.  This enables  network  providers to tailor services
quickly, thereby gaining competitive advantages by reducing their time to market
in delivering multiple services  transparently,  while network managers monitor,
track  and  complete   billing  records  of  all   transactions  in  millisecond
increments.

The software was  initially  developed  and tested over an ATM backbone  network
owned and  operated  by  TeleHub  Network  Services  -- now a sister  company to
TeraBridge  --  to  demonstrate  advanced  signaling  concepts  in  a  switched,
broadband  network,  while  maintaining  high levels of reliability  and service
quality. TeraBridge will now sell the software to major switch vendors, carriers
and service providers looking to migrate to next generation,  switched voice and
data service  capabilities through data-base  technology,  rather than having to
rely on existing network-based solutions or further hardware-based investment in
legacy infrastructure.

Siemens  Information and  Communications  Networks recently signed a three- year
OEM   contract   for  the   PathMinder   software   to  enhance   its  suite  of
MainStreetXpress ATM switches.

The  joint  venture  management  will  report  to a board of  directors  equally
comprised  of  Newbridge  and  TeleHub  executives:  Brian  Jervis,  Chairman of
TeraBridge,  and currently  the Executive  Vice  President,  Switching  Products
Group, Newbridge Networks;  Tibor Schonfeld,  Member of the Chairman's Executive
Council,  TeraBridge and Newbridge Networks;  Kenneth Wigglesworth,  VP and CFO,
Newbridge  Networks;  John  Strand,   President  and  Chief  Operating  Officer,
TeraBridge  Technologies;  Michael McLaughlin,  Senior Vice President,  Advanced
Research and Chief  Technology  Officer for TeraBridge  Technologies and TeleHub
Communications; and William Becker, Chairman of TeleHub Communications.

Privately  held and  located  just  outside  of  Chicago  in  Gurnee,  Illinois,
TeraBridge  Technologies  Corporation is a software  development  and networking
technology company dedicated to providing cost-effective, intelligent networking
solutions  for the carrier  and  network  markets.  For more  information,  call
TeraBridge   at   1-800-782-2000    or   visit    TeraBridge's   Web   site   at
www.terabridge.com.
- -------------------
SOURCE TeraBridge  Technologies (C) PR Newswire. All rights reserved.



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