EXHIBIT 23.1 INDEPENDENT AUDITORS' CONSENT We consent to the incorporation by reference in Registration Statement No. 333-44058 of Carrier1 International S.A. and subsidiaries on Form S-3 of our report dated March 31, 2001, appearing in this Annual Report on Form 10-K of Carrier1 International S.A. and subsidiaries for the year ended December 31, 2000. DELOITTE & TOUCHE EXPERTA AG David Wilson Aniko Smith Zurich, Switzerland April 2, 2001