Some telephones, depending on the brand and model, have the intercom function, which allows to begin communication by sending the signal. When the signal comes, the telephone set rings a signal different from the standard ring tone call. After that the telephone temporarily switches off from the telephone line and works as an intercom.
WavNet Communications, Inc., (WavNet-US) designs, supplies and operates fixed wireless broadband networks for service delivery of voice, video and data services utilizing WiMAX technology