Converge two phones

Hey guys - how would we go about converging 2 phones in asterisk - i know switchvox can do it - but how can you program that in to the dial plan ?

Define “converge”.

Similar to what switchvox does where you can dial in - authorize an “external” number and have all the calls auto forward to that number

Is there a function to do that or does it have to be manually programed into dial plan

Plus - how do you make it persistent over restart if not using realtime

It would have to be programmed.