Christian, Thanks for pointing this out to me. It would seem reasonable that we should probably bring over comparable wording to H.323 or, at the very least, list PROGRESS as one of the messages that stops the T310 timer. I suppose the further qualification would be that the PROGRESS message must contain a PI #8 or #1. Would this sound reasonable? If so, I'll draft such a contribution for the next meeting. Paul

-----Original Message----- From: Christian Groves [mailto:cngroves@bigpond.net.au] Sent: Monday, January 23, 2006 6:11 PM To: Paul E. Jones Cc: itu-sg16@external.cisco.com Subject: Re: T310 timer and PROGRESS

G'Day Paul,

I had a look at Q.931 as the precurser to H.225 to see what the intention was there. Whilst not in the core specification there was a description of the behaviour in an annex described Private Network interconnection.

"M.6.3.1.3 In-band information provided to the physical PINX at the originating interface

Any progress indications shall be conveyed towards the physical PINX at the originating interface.

On receipt of the Progress description No. 1 or No. 8 in the PROGRESS or ALERTING message, the physical PINX at the originating interface shall switch through in the backward direction to the allocated B-channel in order to enable transfer of in-band tones/information, and stop timer T310, if running."

M.6.3.2.3 In-band information provided by the physical PINX at the destination interface

During call establishment, after the first message received in response to the SETUP message, on receipt of a Progress indicator information element with a Progress description No. 1 or No. 8 in the PROGRESS or ALERTING message, the public network shall switch through in the backward direction to the allocated B channel in order to enable in-band tones/information provided from the physical PINX at the destination interface to the calling user, stop timer T310, if running, and if progress description No. 1 or No. 8 was received in the PROGRESS message while T310 was running, restart timer T310.

The public network shall transfer the Progress indicator information element towards the preceding PINX."

Cheers, Christian

Paul E. Jones wrote:

...

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