<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE SONUS
NETWORKS, INC. CONDENSED CONSLOIDATED BALANCE SHEET AS OF JUNE 30, 2000
(UNAUDUTED) AND THE STATEMENT OF OPERATIONS FOR THE SIX MONTHS JUNE 30, 2000
(UNAUDITED) AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL
STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-START> JAN-01-2000
<PERIOD-END> JUN-30-2000
<CASH> 142,987
<SECURITIES> 12,714
<RECEIVABLES> 2,644
<ALLOWANCES> (200)
<INVENTORY> 7,704
<CURRENT-ASSETS> 166,610
<PP&E> 11,234
<DEPRECIATION> (3,440)
<TOTAL-ASSETS> 175,100
<CURRENT-LIABILITIES> 19,377
<BONDS> 0
0
0
<COMMON> 61
<OTHER-SE> 155,662
<TOTAL-LIABILITY-AND-EQUITY> 175,100
<SALES> 7,604
<TOTAL-REVENUES> 7,604
<CGS> 6,017
<TOTAL-COSTS> 6,017
<OTHER-EXPENSES> 34,923
<LOSS-PROVISION> 0
<INTEREST-EXPENSE> 209
<INCOME-PRETAX> (31,389)
<INCOME-TAX> 0
<INCOME-CONTINUING> (31,389)
<DISCONTINUED> 0
<EXTRAORDINARY> 0
<CHANGES> 0
<NET-INCOME> (31,389)
<EPS-BASIC> (2.15)
<EPS-DILUTED> (2.15)
</TABLE>