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.
RocTel International was established in 2002, a wholly owned Irish company with the vision of becoming the best in class service provider to business customers in the Irish and UK marketplace.