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.
Mabrook Voip is a company established in 2009 with 1 customer for a month and now holding hands together with 300 partners from different part of the World.
Read more