The invention is based on the concept of operating a transceiver such that the service features or services, respectively, which are not supported in an interruption-free manner by the mobile radio system in which the transceiver is currently registered are automatically blocked....http://www.google.com.hk/patents/US6549777?utm_source=gb-gplus-share專利 US6549777 - Transceiver and a base station system
