Routing
From Yate Documentation
Yate has multiple routing modules. A routing module is a module that handles (sees) the call.route message.
You can set all routing in a single module or use a combination of modules. If more than one module is used, then the priority that is set in each configuration file determines the order of the modules processing the message. A numerically lower priority means a higher priority of the route. A module can add/modify parameters without handling the message.
This is the list of the routing modules and a How To's for each of them: