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.
Many phone companies offer "cheap" long distance call rates. However, Dukatech goes beyond that, by helping individuals, organizations and business clients get the true value of their money.