In a multi-channel mobile radio telephone system with multiple base stations covering different geographical areas, mobiles may move freely from area to area and automatically originate and receive calls to and from a landswitched telephone network by direct dialing to and from anywhere in the system...http://www.google.com.tw/patents/US4233473?utm_source=gb-gplus-share專利 US4233473 - Comprehensive automatic mobile radio telephone system
