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.
NeuVoice is a service provided by NeuWorld Communications, inc. NeuWorld is headquartered in Tampa, FL, however NeuWorld maintains locations in Dallas, Cleveland (Akron) OH and Southern CA (Long Beach area).