An unlicensed wireless service is adapted to generate the interface protocols of a licensed wireless service to provide transparent transition of communication sessions between a licensed wireless service and an unlicensed wireless service. In one embodiment, a mobile station includes level 1, level...http://www.google.com.hk/patents/US7212819?utm_source=gb-gplus-share專利 US7212819 - GPRS signaling protocol architecture for an unlicensed wireless communication system
