Bluetooth Classic HFP

[Natecam]

I was wondering if it is possible/how hard it would be to take maybe a Huzzah ESP32, and make it act like a host (like a phone) for a Hands Free profile (HFP). I see a lot of stuff on the interwebs about BT LE and BT classic as a node but not so much as a host.
Let me explain my possible project. I have a payphone that I converted to be a handsfree setup for my phone, via an ingenious little device, a Cell2jack. phone connects via BT to BT jack, and jack provides all the weird voltages to power phone. (70V AC to ring the phone, maybe 48V DC when on the hook, and maybe 6-9V DC when off the hook.) I want to also have the phone randomly ring, and when you pick up, it plays sound clips. AND also still work as a phone via BT. So I have two routes. One, physically connect something to the wires inside the phone to provide ring and play sound, but all those different voltage needs, AND to keep it electrically isolated from the Cell2Jack power and vice versa so I don't fry anything. Seems complicated. But, the Cell2Jack supports connecting 2 separate BT phones. That way all the signals come from Cell2jack so no power problems to solve. All I have to do is figure out how to send "ring" commands, and receive "off the hook" commands, and then send audio clips as the "call." Seems like it would be a nice clean setup, except I have not found anything (yet) on the internet to guide me on how to pull something like that off. Obviously I have no experience with BT classic.

any suggestions, even tenuous leads are welcome. Thank you!