For Gruphone 2.0 and later, I’ve forked (and heavily customized) the jasper voice response system. It’s a python framework that glues together a few different text-to-speech engines, and a couple of speech-to-text engines. I’ve only used the PocketSphinx STT engine on dial-a-grue. Jasper is very modular and flexible, but I’ve put considerable effort into making it more integrated into the phone hardware.
For Gruephone 1.0, I hacked up the unix ZIP interpreter….. I
- stripped out all code that needed curses(3).
- stripped out the part that did any line formatting and paging.
- compiled it on the chip, so that it is an ARMv7 executable.
I also did something similar with the Colossal Cave Adventure v4 (660 point version).