looking for an unknown feature

Hi.

I recently have set up the open source version of freepbx for a small company i work with.

They had this feature in their old panasonic central phone where if you dialed an extension and they were busy, you could do something and hangup. Then once the extension was no longer busy, the central would call you and the extension at the same time (or something like that)

I searched, read the docs and explored the admin panel but I couldn’t find a feature that would call the dialer once the extension is no longer busy so… Here i am.

If you know about a feature like this i would really appreciate if you tip me toward the right direction

With Thanks to the community and the open source developers and you guys.

That feature is named in Panasonic PBX as Automatic Callback Busy (Camp-on)
If the destination or line is busy when a call is made, an extension user can set the Automatic Callback Busy
feature. The PBX will monitor the status of the destination or trunk and, when it becomes available, will send
a callback ringing to the calling extension to inform the user.

Asterisk have a similar feature called CallCompletionRequest() which only works with SIP and is not supported in PJSIP.