After a couple of weeks I finished to write a big document lab with 43 pages about Call Routing All-in-one in the Webex Calling solution that coexists with an on-premise Cisco Unified CM and a PSTN/Local Gateway colocated. This document unlike with the previous I shared, includes all Call Routing Implementation from scratch in each component of the architecture: Webex Calling with Trunk Route Group and Dial Plan + CUCM with Route Patterns Route List Route Group and SIP Trunk + PSTN/Local Gateway with Dial Peers.
The part of CUCM side is largely covered with best practices when integration a colocated PSTN gateway and Local gateway to show how to integrate the same physical router with two different SIP Trunk listening on different incoming SIP ports to implement appropriate Class Of Service and avoid call loops and toll fraud. How to manage PSTN calls and Webex Calling Calls on the on-premise CUCM using different Route List and Route Group for the PSTN and Local Gateway. Finally the Class of Service using CSS and Partitions to control calls coming from PSTN through the PSTN Gateway Trunk and from Webex Calling through the Local Gateway Trunk with appropriate inbound CSS.
Then the aspect of call routing on Webex Calling is covered to manage interlocation calls between Webex Teams users, PSTN calls and calls destined to on-premise extensions.
Finally the PSTN/Local gateway part is covered with the dial peers consideration and implementation to manage calls between on-premise users, webex teams users and PSTN Calls.
