An Internet Protocol telephone system and method uses a telephone (26) to place and receive voice over Internet Protocol (VoIP)-based telephone calls and public switched telephone network (PSTN)-based telephone calls. An off-hook condition with the telephone (26) is detected and a sequence of signals...http://www.google.com/patents/US6141341?utm_source=gb-gplus-sharePatent US6141341 - Voice over internet protocol telephone system and method
