Thanks for the answer (was helpfull for me in a way) but I believe the original question wasn't related to what calls can be made with a SIP SRST implementation...
I believe I have a similar concern about SRST (not CME as SRST, but SRST) with the original poster, so I will try to detail the question a bit. (Please correct me if I'm wrong)
Assume you have a branch where you have 2 users, one with a 7911 running SCCP and one with a 9971 running SIP. In a WAN failure, can these two phones fallback to the SAME SRST router on the branch, at the same time, one registering via SCCP and the other via SIP.
I've checked the documentation referenced, and have an understanding of SIP (and SCCP) SRST. But still, there's no indication of simultaneous use of SIP and SCCP on the same SRST router (nor for the lack of).
It's not mentioned in the "Restrictions" section of SIP SRST document, so I wonder if it would be safe to assume it's supported.
Here is an excerpt from the CUCM 7.x System Administration Guide regarding SRST in a mixed environment:
SRST Reference Configuration Options for Phones That Are Running SIP
A remote site may have a mix of SCCP and SIP endpoints in addition to PSTN gateway access. For calls to be routed between the different protocols and the PSTN, three different features will get configured in one SRST router that will allow calls to be routed between phones that are running SCCP, phones that are running SIP, and the PSTN during a WAN outage. In addition, the SRST Reference Configuration window in Cisco Unified Communications Manager Administration provides two fields:
•SIP Network/IP Address—The SIP network/IP address applies for SIP SRST. This address notifies the phone that is running SIP where to send SIP Register message for SIP SRST.
•SIP Port—SIP port of the SRST gateway. Default specifies 5060.
I'm not able to access my old voice mail messages all of a sudden. The recording says something like 'the message is currently not available'. This has never happened before in all the years I have been using this system. I have t...
If you have 2 ISR routers, one acting as Failover, do we need to have both the same number of SRST licenses on the 2 routers?
No. You will only need the SRST licenses on the primary router. Because this feature...