A call shop is a business that provides physical phones for the purpose of making long-distance telephone calls. There are two main types of call shop payment methods; prepaid and postpaid.
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.