Following this thread, it does not make a lot of sense. I am in the same boat now, but with FreePBX 14 (if that makes any difference)
@lgaetz is recommending to use a custom directory.
The confusion part is that is really not directly dialing an extension, but only you have to enter the IVR code, then it takes you to the directory, then you have to take extra time to dial at least three letters of a name.
So anyway, I just tried one extension to test, and it functions, but that seems like a lot of extra dialing of digits. Also, what if they name is forgotten, but on ly extension is recalled?
Surely, there is a better way to do this?
Thinking of something else, I was able to come up with using a custom extension and the Extension Routing module.
Using a dial string, and Extension Routing, the custom extensions are only allowed to use the outbound route for that trunk connecting the two PBXs together.
Seems to be working out