It's a fun thought exercise, but putting "part 96 certification" at the end of my build pipeline sounds pretty expensive. And building a physical cell phone network is stupidly capital intensive. Maybe there are some interesting small scale niches that this would be useful for. But as a daily driver cell phone, I don't think we're ever gonna have an open source modem, at least not until there are significant changes to the spectrum that's in use.

i didn't say that it's cheap. i said that it's possible.