SRST Query

[nickpalmermorewood]

Hi,

I'm new to IPT and am trying to get my head around a few things.

An SRST router is usually used to provide fail over for remote sites during WAN failure etc, however can it still be used effectively in a head office scenario?

Ie. if the voice router is configured with SRST, and the CM fails, am I right in thinking that the phones will fail over to the SRST device which is also the voice interface? And is there a loss of functionality such as Call Pickup, hunting groups etc.

Thanks.

[Rajesh Revuru · Accepted solution]

Yes, you can certainly use the headoffice gateway as SRST. But also depends upon which gateway protocol you are using. Are you currently using H323 or MGCP?

I am not 100% sure about the features like Call Pickup and hunting groups. However you can certainly implement that in SRST mode

[nickpalmermorewood]

Hi,

Thanks for your reply. MGCP is currently in use. I believe that when using CM with SRST you do lose Pickup Groups, hunting etc.

Thanks for your clarification.

[allan.thomas]

If you are looking at pickup groups and huntgroups in a fail-over scenario then it may be of interest for you to look into CME SRST.

What you need to understand is the additional amount of ownership when is comes to administering CME SRST.

For example if you create a huntgroup within CallManager and you add an additional member, you would also need to ensure that you configure your CME SRST gateway to reflect same in the event of failure.

Similarly a display name change, you would not only change the line display in CCM but you need to configure it on the particular ephone-dn as well.

Huntgroup functionality was introduced in CME SRST version 4.x. Depending on your size of deployment, I would avoid CME SRST if you have numbers greater than 50, otherwise it will be too time consuming to manage.

Incidentally the type gateway that is deployed limits the number of possible ephones/handsets which are able to register to it.

I take it you only have a single CCM hence the necessity for SRST? otherwise there would be no reason if you have a pub and sub in the central location.

Regards

Allan.

[nickpalmermorewood]

Hi Allan,

Thanks for your response. Yes currently there is just a single CCM 4.2 hence the V-Router has SRST.

I believe a second CCM is on the way, so then as there will still be less than 1000 phones most probably one will be the primary and the second CCM as the backup, as opposed to use SQL clusters/Intraclusters Pub/Sub for larger numbers.

We do have more than 50 phones so as you mention the admin overhead for using CME SRST would be rather high but it's good to know about the option.

Thanks,

Nick

[STEFAN CHRISTEN]

Hi Nick

Probably loosing the Pickup groups is not the biggest problem while the CallManager is dead ;-)

Basic Call Routing which could help for the Huntgroups can be done with the alias command in SRST. See the following sample config which routes all 2xx numbers to the listed phones:

call-manager-fallback

alias 1 2.. to 251 preference 1

alias 2 2.. to 252 preference 1

alias 3 2.. to 253 preference 1

alias 4 2.. to 254 preference 1

Regards

Stefan