How to prevent miscall of dedicated line

摘要

1. TECHNICAL FIELD OF THE INVENTION;How to prevent miscalls that occur during a private exchange.;2. The technical problem to be solved by the invention;In the related art, the incoming line service is performed even when the signal line detects a call by grounding and the M line of the transmitting private exchange or the E line of the receiving private exchange is grounded by a malfunction rather than a call.;3. Summary of the Solution of the Invention;In a private exchange period connected between a signal line and a voice line, if a specific DTMF is received from the transmitting side private exchange through the voice line within a predetermined time after a call is made from the transmitting side private exchange through the signal line, the receiving side private line is received. An exchange, providing an incoming service in response to said call.;4. Important uses of the invention;Private exchange.