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CUCM compatibility with SRST


Hello There,


I have been reading all through docs and CSC discussion forum regarding  "CUCM compatibility with SRST " where Cisco Doc says 

"Cisco Unified Survivable Remote Site Telephony (SRST) does not depend upon Cisco Unified  Communications Manager, but supports phone loads".

It still unclear to me, let say my CUCM is on running 7.1 version and SRST version 3.1 or 4 , so basically  what i understand it does not matter CUCM with SRST version compatibility it all depends on the phones loads which should be supported with SRST version 3 or 4 correct me if i am wrong. also when phones are registered on CUCM shall have different phone loads ie firmware file supported with CUCM 7 and during fallback in SRST version 3.1/4 will it downgrade to loads which are supported to SRST version and other phones which which are not supported with this version will not fallback/registered.








You may visit below link.

You may visit below link..




Rajeev,It is correct that


It is correct that there is no direct dependency between CUCM and SRST. The SRST version you decide to deploy will primarily depend on the phone models you need to support on the SRST device. Phones should not upgrade/downgrade firmware when failing over to SRST mode. The best advice I can give is to make sure your phone models and loads are compatible with both the CUCM and SRST versions you are running. 




-Bill (@ucguerrilla)

HTH -Bill (b) (t) @ucguerrilla

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thanks Bill, So in a nutshell

thanks Bill, So in a nutshell i can presume that Compatibility b/w CUCM and SRST version would depends on Phones irrespective of version that i am currently running.


Ain't it so weird to find out if any customer having bunch of mixed Phones, then it would be difficult to check every dependency of phones models and loads that are being supported either on CUCM or in SRST. I have been digging from last 2-3 days on to find out any good document which can provide all in one information which i am looking for.


You can find the SRST

You can find the SRST compatibility guides here:


They are very complete and list all phone models.


For CUCM, check this link:


This is also a pretty straightforward resource.



-Bill (@ucguerrilla)


HTH -Bill (b) (t) @ucguerrilla

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