Method of processing intelligent network service call with DTMF subscriber signalling in electronic switching system for toll/tandem

摘要

A method of processing an intelligent network service call in a service switching point (SSP) which has a DTMF processor and is connected to the originating local exchange/transit exchange to provide an intelligent network service. The SSP receives a digit from the other exchange in a R2MFC signalling mode to process a trunk signal from the other exchange upon generation of a trunk line seizure request from the other exchange. The SSP analyzes the received digit to check whether a call from the other exchange is a normal call or an intelligent network service call in which subscriber's information must be received in the middle of the service. If the call from the other exchange is the intelligent network service call, the SSP collects a calling number and a calling category from the other exchange, releases the R2MFC signalling mode and forms a speech path with the other exchange to communicate directly with a service user. Then, the SSP operates the DTMF processor and an announcement sending device to instruct the service user to transmit desired information and collects the desired information from the service user. Then, the SSP releases the announcement sending device and the DTMF processor and processes an out-going trunk call for routing to the terminating local exchange/transit exchange to which a called subscriber belongs.