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.
Telecom Call Center services are based on SIP platform for access and Class 4 Switch for multiprotocol interconnections with all major fixed and mobile operators from Romania and worldwide.