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.
International wholesale carrier services,(voip)A-Z CLI ,A-Z CC CLI routes
expert in dailer termination traffic (call center routes )
contact on skype :lisa.cognitell2
mail :cogsales9@cognitell.net