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I would like to understand when you would use E-SRST as opposed to SRST.  What are these scenarios?




  • 1. Re: E-SRST vs SRST

    SRST is an IOS router feature at the branch. E-SRST however runs on a SRE module at the central site.


    In a nut shell, E-SRST builds on top of SRST by automatically synchronizing user, phone, hunt group, partitions etc from CUCM to CME. Any change on CUCM is propagated to the branch sites without admin intervention, so when the WAN is down, the phone resembles the last changes done on CUCM.


    Reach out to us at access-ccme-cue@cisco.com and we will be happy to walk you through the scenarios.



  • 2. Re: E-SRST vs SRST



    Just to clarify, E-SRST will require running CME on the remote-site router in order to support E-SRST, is that correct?  Is a UMG required for E-SRST, or is it optional?


    Thank you.



  • 3. Re: E-SRST vs SRST
    Srinivasan Kilambi

    UMG is required for ESRST and SRSV. It is a function of the SRST feature license, so you would need that



  • 4. Re: E-SRST vs SRST

    To add to Srini, E-SRST requires the routers at the branches to run CME-as-SRST.


    CME-as-SRST has detailed phone configs, that can be sync'ed from the central site.


    Plain vanilla legacy SRST has no phone specific configuration, so there is no need to sync anything with the CCM at the HQ.



  • 5. Re: E-SRST vs SRST



    Thank you for your prompt reply, one minor question - I was under the impression that SRST was configured localy on the router, UMG intergration was optional.  I am aware UMG is required for E-SRST.



  • 6. Re: E-SRST vs SRST
    Srinivasan Kilambi

    That is correct, E-SRST is enhancement to SRST that can push config ephone etc to the router to simplify that whereas in the past you were maintaining two systems (CUCM and the local router). So now you make the change in CUCM and those changes propagate to the router through UMG. Of course not everything is automated, dial peers still have to be configured etc. Just SRST does NOT require UMG. Only E-SRST needs it



  • 7. E-SRST vs SRST



    So Just to make it clear if you have an existing SRST site that you are converting to E-SRST then you keep the dial peers correct?  Do you need remove any CME config including core lists and ephone and ephone dn config?



    Also why E-SRST does not support SSH or https access to the router?

    Requires having telnet and http server turned on.




  • 8. E-SRST vs SRST

    Correct, E-SRST does not affect your dial-peers.


    Better to start of a clean slate. E-SRST will reconfigure the lists, ephones, dns.


    SSH/HTTPS support is available.

  • 9. E-SRST vs SRST

    Hello All,

    Could anyone please correct me on some things as it concerns Unified Communications. If i want to setup IP telephony solution like Call Manager and Unity Connection for a company that have one HQ and six other branches, what will be at the HQ. Call Manager or Call Manager Express?


    If call manager at HQ, then is the router that will be at the HQ E-SRST capable or SRST? If we use a SRST router at all sites including the HQ, will that be ok?


    I also like to know how many MCS server is needed for Call Manager and Unity Connection at the HQ.


    I will also appreciate it if anyone whould please direct me to where I can get document that indicate how many server, default server hardware configuration for the two products listed above.


    This is really urgent.

  • 10. E-SRST vs SRST

    How many users do you have total?  CUCM supports VM which is a lot better them MCS servers

  • 11. E-SRST vs SRST

    Hi Demitry,

    There is a total of 100 users at the HQ. I don't know how many at each branch yet, we want to focus on the HQ first but whatever we are doing now, we put in consideration the six other sites that need to be connected later.


    I have it in mind to use UCS server but I need to give reasons to customer why they should go for UCS instead of MCS so I still want to know I many MCS server is required for the solutions.



  • 12. E-SRST vs SRST

    IF you have less then 500 users you should go with CME

  • 13. Re: E-SRST vs SRST
    Srinivasan Kilambi

    Actually CCME isn’t being positioned for call control anymore. Cisco recommendation is to lead with BE 3K/5K/6K solutions depending on user count. Then you have the “enterprise” class CUCM code on C200/C210 for larger deployments


    UCS is the preferred strategy since Cisco makes the HW, supports virtualization and other benefits of UCS architecture(too many to summarize). MCS are OEM HW and cannot support virtualization and roadmap is shaky at best.


    In your case since you have multiple sites I would suggest leading with the BE solutions


    Start at the docwiki page for UCS sizing







  • 14. E-SRST vs SRST


    Thanks for the quick response.

    Does it mean we can have CME in all seven sites? I thought there must be at least one CUCM at the HQ.


    Can I use CME in all 7 sites in a distributed deployment scenario?

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