Trunks and Route Groups in Webex Calling
Trunks and route groups in Webex calling are used to link Webex Calling to either on-premises call controls or to existing on-premises PSTN connections. Route groups deliver scale and redundancy for trunk.
Reference:
Configure Trunks, Route Groups, and Dial Plans for Webex Calling
https://help.webex.com/en-us/article/...