AUTOMATIC PRIORITY CONNECTION SYSTEM

摘要

PURPOSE:To prevent a malicious or mischievous call for a public telephone network by providing an operator telephone between telephone at the originating and incoming sides. CONSTITUTION:The connection is impossible when a telephone 1 of the originating side gives a call to a telephone 2 of the incoming side while the telephone 2 is talking to a telephone 3. Therefore, the telephone 1 calls an operator telephone 4 to request the call-back service. Then an operator registers the call- back service to an exchange 6 of the incoming side. The exchange 6 sends a ring-off signal to the operator when a ring-off state is detected. Thus the exchange 1 is called to secure a calling state between telephones 1 and 2.