A multiple mode, personal, wireless communications system exists within a radiotelephone network serving general customers and provides additional services to a select group of customers. The system uses handsets (32) which automatically switch between a standard cellular radiotelephone mode of operation...http://www.google.com.tw/patents/US6243593?utm_source=gb-gplus-share專利 US6243593 - Module for providing wireless call communication services through wire-connected telephone equipment
