I have a CUCM 8.5 system with many sites linked together by a meshed network. Here's the breakdown:
Site 1: Has Pub+Sub, ISR running CUBE for SIP trunk to ITSP (PSTN)
Site 2: Has Sub, ISR with PRI (PSTN), local conferencing resources on the ISR
Site 3: Has ISR with PRI (PSTN), local conferencing resources on the ISR
Here's the deal: When a phone in Site 1 calls & does a conference through the SIP Trunk or conferences phones in the same site, I want that phone to use Site 1's conferencing resources. However, many calls from phones in Site 1 go through Site 2 or Site 3's PRIs for toll bypass purposes. Site 1 users often conference two or more calls through the PSTN, going through the same PRI. I want these calls to be conferenced on Site 2 or 3's resources only if calls are going through that gateway (to minimize WAN usage). Is this something that can be done?
I was thinking this could be easily implemented as I would define special MRGL's for the gateways themselves, but according to my interpretation of Cisco's documentation, the gateway MRGL is only used for determining which MTP resource will be used (no mention of conferencing or transcoding). Am I stuck with using the phone's MRGL for conferencing selection? If so, I would not be able to select a conferencing resource based on the "port of entry/exit" to the PSTN... Any thoughts?