The term phonepatch usually refers to the hardware device used to connect a radio transceiver and a phoneline. Asterisk-phonepatch do that task, but it's mainly software, as it uses the Asterisk software PBX.
You need to setup some hardware interface between computer and radio, to control audio (using the soundcard as D/A, A/D converter), PTT (Push-to-Talk) and, optionally, carrier detection.
Source code and binary packages for Debian (so, also Ubuntu) are available.
Asterisk-phonepatch is free software.