Abstract: A general global gateway (GGG) uses shared secret data to authenticate between a CDMA network and a GSM network such that a mobile station having a subscription in a GSM network can roam into a CDMA network and be authenticated to use the CDMA network without having a complete ANSI-41 subscription. The goal of authenticating a GSM subscriber in an ANSI-41 network using GSM authentication credentials is achieved by substituting encryption key Kc as SSD-A in the standard ANSI-41 computation of AUTHR using a CAVE algorithm.