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.
Spirited Broadband provides Business class services either by tradional circuitry or via IP. SBB specializes in trunking existing PBX`s and will be happy to serve your Business needs today.