Cisco SRST Configuration
Cisco SRST configuration for SCCP phones
First, check this nice Youtube link as an introduction to configuring Cisco SRST.
Configuration on the branch1 voice gateway:
I first used my VTGO phones to experiment SRST in my home lab. They did not work when the WAN failed. So I switched for an instance of Cisco IP Communicator instead.
The mini lab I used to write this post is basically composed of:
- a voice router
- Cisco CIPC
In normal situation, I mean when the WAN link is up, the phone is registered to CUCM:
I configured the voice router for SRST. Pay attention that configuring CUCME as SRST is another thing.
In my home lab, I configured the voice router with SRST (see the Youtube link I provided above). Then I configured the emulated PSTN as a CUBE. I added the four possible “allow-connections” statements.
I make sure the Emulated-PSTN router is configured as CUBE properly:
I configure an appropriate dial peer for PSTN connectivity to HQ. I configured a dial peer on BR1 router to be used when the phone is in SRST mode. This dial peer matches calls to HQ DID numbers, and routes on the Emulated PSTN.
I shut down the WAN interface on branch 1:
The phone at branch 1 gets registered to the local router in SRST:
The CIPC phone displays a meaningful message:
I make a call from branch 1 to the full PSTN number of the HQ:
When the call goes from Branch 1 to the PSTN link, the call leg matches dial peer 111 on PSTN router. Then the outbound call leg matches dial peer 1717:
I still have to properly format the calling number (from branch1) to be displayed correctly on HQ phones. I could do that with voice translation rules and profiles: