I can't fix an external forward in the extension (sip yealink t20p).I do not know if we will create some "route inbound" or "outbound route" to create a markup for the function rule, if it fixed in the PBX, extensions, forward, the external forward work properly, however I need to fix the external forward on the phone so the customer activate it when you need it.
I can't fix external forward directly in SIP phone (yealink t21p), with follow me in pbx it's working properly, but the client want aleatory/personal forward to external number and its don't work .
I still haven't found the routes manual, please same example to do it ?.
Rules are different as many as you think.
Examples are in the routes manual.