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.
(TGLA)Telegestiones Latinoamericanas is a 100% Spanish company that in recent years, has been providing integrated telecommunications solutions to leading companies in different economic sectors in Latin America, North America and Europe