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 module or use a combination of them. If more than one module is used, then the priority that is set in each configuration file determines the order of the module processing the message.A numerically lower priority means a higher actual 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: