Ben,

Discussion in Sun River brought out that a careful reading of H.225, H.245, and H.323 implies the following:

1. It is allowed to start H.245 negotiation as soon as the CallSetup message is received. 2. Once H.245 negotiation begins, it can proceed to open logical channels at it's own pace. 3. Once an open logical channel is opened and acknowledged, media streaming should begin right away.

So it seems to be entirely possible to do media streaming before a CONNECT message, and the CONNECT message can retain its usual Q.921 meaning.

You can call this "deferred Connect", but it'd be better not to give it any special name. It's just a compliant H.323 implementation. The CONNECT isn't deferred, it comes at just the right time -- when the endpoint wants to signal that the call has connected.... This may or may not be after some media has been streamed.

Scott Petrack Principal Technologist VocalTec Communications Ltd. petrack@vocaltec.com

btang@LUCENT.COM on 09/09/97 04:50:36 PM

Please respond to ITU-SG16@mailbag.jf.intel.com

To: ITU-SG16@mailbag.jf.intel.com cc: (bcc: Scott Petrack) Subject: Re: A scenario that cannot be solved without APC-1280 or deferred "Connect"

Gur, Your observation leads to the general question that whether it is necessary to support the opening of a media channel during the Q931 call signaling procedure. This concerns other scenario as well. For example, when an H323 endpoint calls a POTS user via a gateway, while the Q931 call signaling is in progress it may be required to have a voice channel opened between the endpoint and gatweay to forward a PSTN special announcement ("sorry, the number you dialed is not in service") back to the endpoint. As I remebered, a while ago there was a decision made from this subject group about h323 implementation, that no capability exchange will take place before the Q931 signaling is completed. I am not sure about the rational behind it, but maybe that can be brought up again for discussion. I looked at APC-1280 and found no descriptions for the procedure of using the Progress-UUIE which is proposed to solve the above-mentioned problem. Will this be added later on? Ben Tang Lucent Technologies btang@lucent.com