Paul,
 
In QSIG, which is essentially a symmetrical variant of Q.931, T310 is stopped on receipt of a PROGRESS message with progress indication 1 or 8. This behaviour is useful for a number of supplementary services where expiry of T310 could terminate the call attempt too soon.
 
Regards,
Ernst

From: Paul E. Jones [mailto:paulej@PACKETIZER.COM]
Sent: Monday, January 23, 2006 11:51 PM
To: itu-sg16@external.cisco.com
Subject: T310 timer and PROGRESS

Experts,

 

Recently, I asked what should happen when an endpoint receives a PROGRESS message indicating that there are in-band tones and announcements.  Should the T310 timer be stopped?  H.225.0 seems to be silent on this, but it would certainly seem that it should be stopped.

 

Should we stop the timer or should the timer continue to run?  It will expire in short order (assuming a default value), which suggests the timer ought to be terminated and T301 started.

 

I would appreciate your input on this.

 

Paul