Caller ID Between Servers

Good day!

I have finally found the solution for linking my Asterisk servers using IAX trunks but now have something related that it driving me crazy. I can’t get the caller id to go across the trunk and show me whos calling.

Here’s how it is configured.
I made an IAX extension on each server and then connected an IAX trunk back to the servers using that extension.
The connection is up and I can call from one to the other but I’m not getting caller id.

If someone can tell me how to do this I would be very grateful. As would my head as I would stop banging it on the table.