Exhibit 23.2 CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS As independent public accountants, we hereby consent to the incorporation by reference in this registration statement on Form S-8 of our reports dated January 21, 1998 included in Excel Switching Corporation's Annual Report on Form 10-K for the fiscal year ended December 27, 1997 and to all references to our Firm included in this Registration Statement. ARTHUR ANDERSEN LLP Boston, Massachusetts May 1, 1998