<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE COSINE
COMMUNICATIONS, INC. CONDENSED CONSOLIDATED BALANCE SHEET AS OF SEPTEMBER 30,
2000 (UNAUDITED) AND THE STATEMENT OF OPERATIONS FOR THE NINE MONTHS ENDED
SEPTEMBER 30, 2000 (UNAUDITED) AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000

                             
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-2000
<PERIOD-START>                             JAN-01-2000
<PERIOD-END>                               SEP-30-2000
<CASH>                                         285,012
<SECURITIES>                                    56,971
<RECEIVABLES>                                   19,078
<ALLOWANCES>                                         0
<INVENTORY>                                      9,051
<CURRENT-ASSETS>                               356,602
<PP&E>                                          30,760
<DEPRECIATION>                                   7,152
<TOTAL-ASSETS>                                 381,270
<CURRENT-LIABILITIES>                           42,072
<BONDS>                                              0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                            10
<OTHER-SE>                                     325,609
<TOTAL-LIABILITY-AND-EQUITY>                   381,270
<SALES>                                         14,823
<TOTAL-REVENUES>                                14,823
<CGS>                                           14,266
<TOTAL-COSTS>                                   14,266
<OTHER-EXPENSES>                               112,242
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                               1,257
<INCOME-PRETAX>                              (109,308)
<INCOME-TAX>                                         0
<INCOME-CONTINUING>                          (109,308)
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                (2,500)
<CHANGES>                                            0
<NET-INCOME>                                 (111,808)
<EPS-BASIC>                                     (1.50)
<EPS-DILUTED>                                   (1.50)