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.
History of NGTEC Corporation goes back to 1993 and closely connected with foundation of the Newcom Group (www.newcom.mn), a first company to provide telecom solutions and system integrations which then has grown into today