We have a CUCM version 10.5 in our regional office. We also have a remote location that uses our regional office CUCM for call set up/tear down but has their own local gateway and PRI, equipped with Cisco Unified Survivable Remote Site Telephony (SRST).
Yesterday through an unfortunate chain of events, we suffered a loss of power to our Call Manager, among other things. It took out our office phone system. It also took down our remote location. Once power was restored we were back up in about 15 minutes.
My question: Since our remote site is equipped with SRST, should they have remained operational?
US Fish & Wildlife Service
Yes, phones should register to srst if registered CUCM node is unreachable until the connectivity between phone and srst router goes down. Incorrect configuration of srst is always an exceptional. Do verify on phone configuration (.xml) file whether srst address is correctly updated?
You may also refer to below link that explains the concept of srst:
Yes, if things are set up correctly the phones at the remote site should have registered with the local SRST router.
There are a lot of things that could be the cause but one of the first things to do is verify that the remote site's device pool (I assume it has it's own) has a SRST router specified and that it can be seen in the phone's themselves.
Common issue I see besides the obvious SRST reference in DP, is that folks forget to configure SIP SRST and only have SCCP configuration on the remote gateway and then deploy SIP only phones such as 88XX, 78XX. Make sure you have proper SIP SRST configuration on your gateway if using SIP devices.