[asterisk-dev] how to link FreePBX IVR step to something inside extensions-custom.conf?

[Edward de Jong]

I have a main IVR,one stage of which when the user presses 9 I want to jump to code written in Ye Olde Asterisk dial plan language, via a custom context I am creating inside the "exceptions" dial plan file called extensions-custom.conf, which is a magical file not overwritten by FreePBX each time you update the configuration via the Web GUI. 

My question is fundamental, and simple, and that is how do you link to the the custom context, which in my case is a zip code -asking routine, with a context name of [zipcode]?  How do i do a forward link into the custom context, and if the user presses some keys to escape my routine I want to return to where I came from… how do i do  "return" basically inside, how do you jump back to an IVR stage generated by FreePBX.. I don't want to have to edit each time is use FreePBX any files FreePBX overwrites, because we make changes all the time in the dial plan.

Any help is appreciated.