SRST for more than 720 users

boonwah-tay · ‎05-31-2007

I have 2 branch sites with 2000 users each. Centralized Call Manager 4.1 cluster (clustering over WAN) is installed at central data centers which are in different sites.

Like to have SRST for the two branch sites. SRST limit is 720 but user is 2000. Would like to know how to have SRST for more than 720 users?

Can we 3 ISR each with 720 SRST users and split the 2000 users into 3 group. Each group if 720 users will use one of the three router as its own SRST reference router and through properly designed device pool?

Thanks!

jolo07310 · ‎05-31-2007

Hi,

Here is my 5 cents.

You said you have Centralized design and cluster over WAN also. I suggest that since you have CCM cluster over WAN, why dont you put another subscribers for those two branches?? Unless there is not enough bandwidth between those branches and central data center.

If you have to use SRST for some reason. And yes, you can have 3 ISR and create 3 differen device pool with different SRST reference, and then assign to end users.

Ken

boonwah-tay · ‎05-31-2007

In traditional SRST mode, the amount of features you can implement are limited. If you want huntgroups, call park, pickup groups, BACD queueing etc, SRST has limited capability to do all these functions.

I read from http://www.cisco.com/en/US/products/sw/voicesw/ps4625/products_configuration_guide_chapter09186a00807e0566.html

that with CME 4.0, Cisco introduced CME with SRST fallback support and this support full telephony features even in SRST mode. Questions are:

1. CME can support only up to 240 phones. Where as SRST can support up to 720 phones. How can we then achieve CME SRST Fallback Support with up to 720 Phones?

2. When ordering, should we buy a maximum CME license (240 users) and also buy a maximum SRST license (720 users)or we just buy the CME license only? I read from the the CME and SRST license are transferable but however CME gives you more features. Need some clarfication here.

Thanks!

johnnylingo · ‎05-31-2007

Can we 3 ISR each with 720 SRST users and split the 2000 users into 3 group. Each group if 720 users will use one of the three router as its own SRST reference router and through properly designed device pool?

Yes, absolutely. With 3 3845s each with its own SRST reference, this is possible. You then break your phones up to 3 different device pools, each with a separate SRST reference.

But I do agree with the other poster that with 2,000 users it might make a lot more sense to just place subscribers at each branch site. This is the preferred method if you have 2 Mb+ of spare bandwidth. If that is not the case, then you can go with a separate cluster connected via Inter-Cluster trunk, although that complicates your management and dial plan.