I can recognize a Large Language Model response a mile off and I can’t remember ever seeing a valid one in the Asterisk or FreePBX forums.
For FreePBX 16, details of how to add custom headers are given in
Note that the preview mangles the code; you need to follow the link to the original posting.
As FreePBX 17 has to work with Asterisk 21, which finally removed support for macros, I assume there will be differences for FreePBX 17, although I assume the hook is still supported, with a different interface.
However, personally, I’m against using the general custom header mechanisms to do things which are supported by Asterisk itself. Without actually running a test, which I’m not in a position to do, I’m not sure if the Set(CALLERID(…)) previously mentioned has to go in the same dialplan hook, or one run earlier.
Back to custom headers, you might want to note the remarks about the instability of the interface, and the obsolete documentation, in:
Again follow the link. This time because the preview doesn’t account for the fragment part of hte URI.