Signaling Session Timeout; Audio Session Timeout - Nortel 222 User Manual

344 Appendix M SIP
If the primary WAN connection fails, the SIP client needs to re-register with the
SIP server through the secondary WAN port to have the SIP connection go
through the secondary WAN port.
When the Business Secure Router uses both of the WAN ports at the same time,
you can configure a routing policy to have the voice traffic from any IP address
with UDP port 5060 and the RTP ports go over a specified WAN port.
Enabling or disabling the SIP ALG
The Business Secure Router SIP ALG is turned off by default to avoid
retranslating the IP address of an existing SIP device that is using STUN. If you
want to use a SIP client device (a SIP phone or IP phone for example) behind the
Business Secure Router without STUN, use the ip alg enable ALG_SIP
command to activate the SIP ALG.

Signaling session timeout

Most SIP clients have an expire mechanism indicating the lifetime of signaling
sessions. The SIP UA sends registration packets to the SIP server periodically and
keeps the session alive in the Business Secure Router.
If the SIP client does not have this mechanism and makes no call during the
Business Secure Router SIP timeout default (60 minutes), the Business Secure
Router SIP ALG drops any incoming calls after the timeout period. You can use
the ip alg siptimeout command to change the timeout value.

Audio session timeout

If no voice packets go through the SIP ALG before the timeout period default (5
minutes) expires, the SIP ALG does not drop the call but blocks all voice traffic
and deletes the audio session. You cannot hear anything and you must make a new
call to continue your conversation.
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