EXHIBIT 23.1

                         CONSENT OF INDEPENDENT AUDITORS


    We consent to the incorporation by reference in the Registration Statements
(Form S-8 Nos. 333-56496 and 333-99181) pertaining to the 1997 Stock Plan, 2000
Stock Plan, 2000 Employee Stock Purchase Plan, 2000 Director Option Plan and
2002 Stock Option Plan of CoSine Communications, Inc. of our report dated
February 6, 2004, with respect to the consolidated financial statements and
schedule of CoSine Communications, Inc. included in the Annual Report (Form
10-K) for the year ended December 31, 2003.



                                                           /s/ Ernst & Young LLP

San Jose, California
March 24, 2004