A method for powering a system for transmitting and receiving multiple telephone transmission signals over a single twisted pair. The method also powers down a portion of the system. An analog signal from a local switching station is converted to an 80 kbits/sec signal for transmission over a twisted...http://www.google.de/patents/US5627833?utm_source=gb-gplus-sharePatent US5627833 - Digital added main line system with power-up and power-down features
