Exhibit 23 INDEPENDENT AUDITORS' CONSENT We consent to the incorporation by reference in Registration Statement No. 333-46954 on Form S-3 and Registration Statement Nos. 33-64611 and 333-79165 on Form S-8 of Covista Communications, Inc. (formerly Total-Tel USA Communications, Inc.) of our report dated April 11, 2001, appearing in this Annual Report on Form 10-K of Covista Communications, Inc. for the year ended January 31, 2001. /s/ DELOITTE & TOUCHE LLP New York, New York April 24, 2001