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CME and SRST how to detect failure of UCM

I've read the docs and searched the forums but still cannot find a clear answer on this.

In a gateway configured for CME / SRST how does it detect that it has lost its connection to the upstream UCM ?

Do I need to do a MGCP configuration and let that process trigger the SRST mode on the GW?.  This doesn't work for me as the gateway needs to run H.323 back to UCM for a whole buch of reasons and mgcp overrides my h.323 configurtion (MGCP kills caller ID on my 1FL voice ports, hence h.323)

OR ...

do the individal phones (with the gateway IP address) detect the UCM failure and connect over to the gateway and the gateway doesn't care about the status of UCM and does no polling to detect if it up or down.  Then when do the phones try to detect of the main UCM is up again.


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Cisco Employee

Re: CME and SRST how to detect failure of UCM

You can use SRST with H323 or MGCP.

The GW itself does not monitor CUCM, as phones hunt thru the CUCM group they send keepalives to all the possible options, if any of the options sends an ACK they register with it. If they reach the SRST reference and send keepalives to it, when the keepalives are received, SRST kicks in.

Phones keep sending periodical keepalives to the CUCM servers, once they receive an ACK from any of them, they unregister from SRST and register back to the server.



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