EXHIBIT 23.1


                    CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS


As independent public accountants, we hereby consent to the use of our report
dated May 24, 1999 (except for the matters discussed in Note 16 to the
Consolidated Financial Statements, as to which the date is August 17, 1999) and
to all references to our Firm included in this Report on Form 8-K/A. Our initial
report dated January 26, 1999 included in Excel Switching Corporation's Form
10-K for the year ended December 31, 1998 is no longer appropriate since
restated financial statements have been presented giving effect to a business
combination accounted for as a pooling-of-interests.


                                                            ARTHUR ANDERSEN LLP



Boston, Massachusetts
August 26, 1999