[cisco-voip] h323 Call Preserve and features

[Pawlowski, Adam]

I've been working with our PRI IOS gateways a bit, trying to improve on MGCP's resilience in  regard to service when the CUCM is down or transitioning. We service a non-PSAP police department on our campus, and they've asked the world of us in regard to never losing a call. I don't think this is  possible, but, we've demonstrated to them how MGCP works, and they're not satisfied. Presently, we have MGCP with 3 cucm nodes and the shut-backhaul-interfaces command enabled. Calls will overflow to our other trunk group at another loc if the Ds are down here. The telco has not been reasonable about establishing any other extended services (network call redirect, DTO) to make that situation better, so while MGCP is failing over due to WAN/CUCM outage, calls are not terminated and die off.

I have set a test gateway up with H323, which works (save for 5ESS Fac IE CNAM which is fine), and have set up call preservation. Media stays up when I null route one CUCM or another, to simulate a CUCM reload or failure. However, there's no reflection of a loss of call control from the station (SCCP 7965). If you attempt to invoke call hold or such, media ends, the call does not get held, and the call dies in place on the set (both ends - the remote call off the gateway hangs in limbo too). At one point I hit transfer on the set and heard the hold tone when it opened a new call. Am I missing something in configuration that the control of the call is never re-established, or does not seem to do so properly? Is this how this feature is intended to operate? 

Adam P
SUNYAB