Signaled Telephony Events in the Session Initiation Protocol(SIP)
Cisco Systems
This document demonstrates a way for interested SIP User Agents which are not a party to the media of a call or session, to receive SIP event notifications when signaled digits, or other specific telephony-related events are detected. This is useful for a variety of applications that monitor calls for a specific event (e.g.: a long pound, special sequence of digits, or a fax signal) and--only then-- take an active role in the monitored calls.