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.
IPness is a product of The Phone Company nv/sa, The Phone Company of Belgium was formed in 1996, and has been serving large international carriers with high-tech innovative solutions and special value-added services.