Abstract: A method for effecting the communication of digital signals over telephone lines includes the steps of generating a voltage at a first level for providing an inactive state signal directed to a plurality of slave transceiver units and generating a voltage at a second level for provding a first carrier detect signal directed to the slave units. A digitally encoded first data signal is then generated, has a peak amplitude at a third voltage level and is also directed to the slave units. In response to the first carrier detect and first data signals, a voltage will be generated at a fourth level for providing a second carrier detect signal directed to a master transceiver unit. Thereupon, a digitally encoded second data signal will be generated to have a peak amplitude at a fifth voltage level and is also directed to the master transceiver unit.