I’ve found some old threads regarding this with no real solution that I can find. Some recommend Dundi but FreePBX “offers limited support for Dundi trunks…”. Does this mean there’s a better way to make remote extensions accessible via IVR?
I was able to create Misc Destinations for each extension that was on the IAX2 peered PBX, which allows you to see the option in the FreePBX GUI for the IVR. Of course you will not be selecting Extension as the type, but instead selecting Misc Destination. 
Interesting. On my version, I see the types of extensions are Sip, IAX2, Dahdi, Generic, Other or None. Do you recall which type you chose to be your misc. extension?
Yes, it is not a trunk or extension type… it is an application/module. “Misc Destinations”. You can do all sorts of funky things with that and it’s close buddy “Misc Applications”. Bottom options of that image.
Thanks! Didn’t have that module installed. Now I do. Worked perfectly. Thanks so much for the tip!
So glad that it worked out for you! I use it all the time.