| 摘要 |
PURPOSE:To process normally an outgoing/incoming call with high reliability by devising the controller such that a succeeding step is proceeded to process an incoming/outgoing call even when a line current or a dial tone or the like from an analog exchange network cannot be detected and confirmed. CONSTITUTION:No polarity inversion function is included for the specification of an analog exchange network 2, a tone frequency is selected for 500Hz and a mail equipment is going to send a facsimile mail to a facsimile equipment. In this case, a call is given to the exchange network 2 and when a line of a communication controller 4 is broken on the way, monitoring for a time t1 is started after the start of dialing and when a line current is detected and confirmed within the time t1, the dial tone is monitored. When the line current cannot be detected and confirmed in the time t1, a line current detection flag is set and the dial tone is monitored similarly. The operation is implemented by a similar step in the network 2 and even in the absence of a delay in the exchange network, difference from a tone frequency and a polarity inversion function, the incoming/outgoing call is processed by a usual step. |
