Hi, There is an issue with the transport of the CC possible indication in the 486 response and the forking proxies.
The issue is following - consider an INVITE from A to AOR-B that gets forked by a proxy to AOR-C and AOR-D. If any of the targets AOR-C and AOR-D is busy the possible CCBS possible indication in any of the 486 responses will not survive the response aggregation in proxy and will not make it's way to the A. Let's call this scenario A) proxy with no monitor forking to foreign AORs. In my opinion there is no issues, as there is no possible way to make such a scenario function fair, so there is not problem is the CC service will not function in this case at all. In the following scenarios the assumption is that there are no proxies from the scenario A) preceding the acting proxy. If there are any than the scenario A) applies. Consider an INVITE from A to AOR-B that gets forked by the proxy with monitor to the Contact-B and AOR-C. If the Contact-B is busy and AOR-C is ringing, the 486 and 180 responses get aggregated to 180 with no CCNR. If both Contact-B and AOR-C are busy the proxy with the monitor will provide the 486 with CCBS possible indication monitoring the status of the Contact-B. If Contact-B is ringing than independent from the state of the AOR-C the proxy with the monitor will provide the 180 with the CCNR possible indication. Let's call this scenario B) proxy with monitor forking to local contacts and foreign AORs Scenario C) would be proxy with monitor forking to local contacts only. This is where the local policy for the aggregation and generation of the CC possible indication would apply. To sum-up - the scenario B and C will function properly, the scenario A will not function, but this is acceptable from my point of view as the A) scenario is not the common case. This all means that we do not have to do anything special to support the transport of 486 or 180 messages carrying the CC possible indication from B to A. Comments, questions? Greetings, Denis
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