Question about CM-to-SRST via the PSTN

[imlazar]

I'm trying to understand how the following scenario might work, pointers to any relevant docs are appreciated:

Network Configuration:

- Site A has a CallManager server

- Site B has SRST and about 20 users, it's call processing is done by the CM at Site A. It has a WAN link to Site A and a PRI to the PSTN for backup only. All in-bound/outbound calling from the PSTN goes through Site A.

- Incoming calls to DID numbers for Site B users terminate on the CM Site A and are routed to the appropriate phone on Site B

- Site A has been configured to route calls across the PSTN to Site B if the WAN link fails.

Here's the scenario:

- WAN link fails

- Site A receives a call from the PSTN destined for a user at Site B

How does Site A route the call? Does it establish some sort of IP trunk between the CM and the SRST-enabled router and then encapsulate the call?

Thanks!!!

[mparekh]

From what you described you have a multi-site centralized call processing model.

When the link fails between Site A and Site B, incoming calls from PSTN destined to Site B will most probably go back out to PSTN through the carrier network into the Site B backup PRI. This is assuming that when the WAN link fails your provider re-routes Site B's DID from Site A PRIs to Site B PRI.

Link for Deployment Design

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a0080447510.html#wp1045315

Cisco's SRST Site:

http://www.cisco.com/en/US/products/sw/voicesw/ps2169/index.html

[mwheinz]

The caller goes to voicemail if configured, or gets a busy if it's not. The call will not get routed back out to the PSTN, to the backup line at site B.

Why would you have a PRI for backup only at site B? I would think perhaps 2 or 3 analog circuits would be fine, enough for 911 calls and SRST.

Good luck!

[jneiberger]

I think there may be a future feature that might help with this scenario. Ask your Cisco account rep about it.

[spverizonrd]

You must be create 2 intercluster, example

One named Inter_WAN and other named Inter_PSTN

Next you need associate these intercluster at device pool name SRST_Way.

When you define the route patern for out goin call you need to select these device pool