UMTS telecommunications system for enabling a mobile station to receive voice-over internet protocol calls when roaming

摘要

A telecommunication system including a mobile station, and means for a mobile station to receive voice-over Internet Protocol (VoIP) calls when it is roaming away from a home network, comprising: means for informing a serving GGSN of the International Mobile subscriber Identity (IMSI) of the called mobile station, and means for enabling a local VoIP control server to map a called MSISDN number to the IMSI number.