• jmp.chat phone number, shared between spouses as a “family number” either of us can answer at home or away from phone.
• Cell2Jack device that converts bluetooth phone call into landline phone
• Cortelco 2500 telephone

Video with sound here. Video was taken of Android phone Cheogram app, but I will instead use this setup with Raspberry Pi 4 + Waydroid/Lineage OS and Cheogram app in the coming days.

Yes, you can answer and dial out from the telephone instead of device for integrated phone apps like Cheogram. For Signal, I have to tap answer on device but can pick up telephone to continue the audio call.