Simulating changes in telephone subscriber line

Abstract From the Canadian patent

A fixed wireless access subscriber unit containing a wireless transceiver and a telephone subscriber line interface circuit which supports privacy and remote release of hold between the subscriber unit and extension telephones are disclosed. The subscriber unit detects when the primary handset, or an extension telephone set goes off-hook. In response the subscriber unit modifies the voltage and/or current characteristics on the telephone subscriber line which connects the extension sets to the subscriber unit in such a manner that extension sets connected to the telephone subscriber line will sense when the primary handset goes off-hook.