[Asterisk-Users] Understanding and Troubleshooting Analog E&M

[Eric Wieling]

For the Archives.

This document discusses analog recEive and transMit (E&M) Start Dial 
Supervision signaling. Start Dial Supervision is the line protocol 
that defines how the equipment seizes the E&M trunk and passes the 
address signaling information (sends dual tone multifrequency (DTMF) 
digits). The three main start dial supervision protocols used on E&M 
circuits are Immediate Start, Wink Start, and Delay Dial.

http://www.cisco.com/warp/public/788/signalling/em-supervision.html