sip.conf Sielence Detection: silencedetecthangup

Syntax:

    silencedetecthangup=X

i.e.

[jane-7960]
type=friend
secret=foo
context=inbound
silencedetecthangup=25

This command is used to set a time out for asterisk to end a call after a certain amount of secconds that it “hears” complete silence from the peers end. This is helpfull for phantom calls. If asterisk does not hear anything in X amount of seconds it will terminate the call. The “silencedetecthangup” creates a timer, in seconds, that would start ticking as soon as some period of one-way audio was encountered while * talks to this peer. If the peer has not transmitted any audio to us in X amount of seconds, terminate both legs of the call.

This information was obtained from:
http://bugs.digium.com/view.php?id=207