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.
Prime Time Telecoms Inc, is a privately-held telecommunications service provider and one of the leading companies in the rapidly growing VoIP interconnectivity market in Japan. A registered (ITSPs) and VoIP Wholesale Providers.