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.
Founded in 1988, Citilink Group is today one of the leading lights in the Nigerian business community. It is a multi-investment company with interests in communications, information technology, finance, travels and tours, and consultancy.