In this article I’m describing the implementation of site code dialing, in my CCNP Collaboration home lab. I am taking an example of one HQ with site code 801, and a branch office with site code 803. The inter-site code I am going to use is the 0, to dial between sites.
The purpose is to use inter site code dialing to reach other sites across the WAN, which is also called Toll Bypass. And if the WAN breaks then the communication takes place across the PSTN, which we also call PSTN fallback.
CUCM configuration
Gateway configuration
Here is what the configuration would look like on the HQ gateway:
and here is the part on the branch office site:
In order to emulate PSTN, I set the following configuration:
Testing the configuration
First, when the WAN connection WAN is up between HQ and the branch site, we get the following result:
and the WAN connection is disrupted, the communication falls back to PSTN:
