"where I can hook up an actual phone and receive and send calls."
So what you want is something called an Analog telephone adapter: https://en.wikipedia.org/wiki/Analog_telephone_adapter and then use a program like Asterisk (https://en.wikipedia.org/wiki/Asterisk_%28PBX%29) - which is in the Trisquel repo already, waiting for to be installed - running on a computer somewhere for the phone to register with. Asterisk handles the voip and your voicemail and whatnot and ta da. Asterisk is rather powerful: It can register with an external voip provider or you could become your own and have your own voip system or whatever. Have fun.
