I just did an upgrade for a customer on their VCS Control from x5 to x7.2. Customer has neighbor zones to three regional CUCM clusters, (US, EMEA and APAC). Customer reports that video phones registered with the EMEA cluster (CUCM 8.6.1) drop after 15 minutes, the other two CUCM clusters are not having this issue. The US cluster is running 8.6.2, and the APAC cluster is running 8.6.1 just like the EMEA cluster. This sounds like some osrt of SIP timer negotiation failure on the CUCM side, but I'm at a loss as to which one it may be.
Looking for suggestions or hints.
thanks,
rf