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New Member

SRST Timer

Hello Guru,

after MGCP fallback to SRST, what is the timer the SRST router back to CUCM? immediately? or some delay?

if it is immediately and if WAN link flaps, will the T1 D channel flap as well?


Re: SRST Timer


Once the connection with the call manager is reestablished

the ip phones cancel their registeration to the SRST and reregister with the call manager

also could you plz show the 2nd ask in more details?


New Member

Re: SRST Timer

thx for the reply

the mgcp gateway will register back immediately after IP connectivity to CUCM servers restored

however, IP phones don't because the default 120 second

so during the 120 seconds, no outgoing calls via gateway, this is too bad

other thing, if the IP connectivity between CUCM and gateway are flapping, so the PRI D channels will be up/down, this is too bad as well


Re: SRST Timer

If you plan to use the default time interval between keepalive messages, which is 30

seconds, you do not have to perform this task.



1. call-manager-fallback

2. keepalive seconds

3. exit

New Member

Re: SRST Timer


I am thinking we updated in same time, I did take a look the timer setup under call-manager-fallback, but it is for the communicate between SRST router and IP phones, not between SRST and CUCM


Re: SRST Timer

SRST will take over after 3 incomplete ntfy messages are sent to the call manger from the router. this is not configurable.

New Member

Re: SRST Timer

can I ask the SRST router stay there for certain time before switch back to CUCM?


Re: SRST Timer

sorry for late reply,

in cucm, in gateway configuration page there is option for

swithcback timing and swithcback uptime-delay

New Member

Re: SRST Timer

unfortunately, the way you introduced not working

I tried different combination, including config

ccm config

ccm config server

mgcp restart-delay

ccm switchback uptime-delay

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