Assign extension credentials to VOIP integration (to support Unifi Talk)

It would be great if we could give the VOIP integration the ability to login to a PBX as a user, instead of only accepting direct-to-IP calls.

The reason I’m asking for this is that I have Unifi Talk phones sprinkled throughout the house (to serve as intercoms or just have something like plain old house phones). Unifi doesn’t seem to support direct-to-IP in all of the searching that I’ve done. So I would like to create an extension for Home Assistant, and take those login details and allow the integration to login using them.

If there’s an easier way to support Unifi’s annoyingly locked-in PBX, I am all ears. I was looking for feature command (star codes) that would allow me to dial an IP, but I can’t find anything similar to the *47 that Grandstream has.