Answering to your "GSM not open" comment - yes, the GSM baseband itself is not open-source, and I won't be able to change that alone - I have neither skills nor time. My plan is to make all the other parts of the phone open-source, so that when an open-source baseband appears, there's a platform to attach it to.

Hey, other programmers manage to write software that isn't riddled with bugs, I hope to be able to keep up with them =)

It's a mighty goal and you're probably more than capable developer but even bigger organizations have failed to produce working phone sw stacks while leveraging open source components.

Therefore while it's a great tinkering project I'm really sceptical about the actual value this could have for "end users" unless the value is the tinkering itself ;-)

+1 for this. A GSM/3G/LTE stack isn't something you can write in an afternoon. I'm on such a project for my company for several months now and I'm probably still a year away from just being able to push a single IP packet through it.

That's why I won't be doing it myself - I'm just going to provide the platform, there are already people working on an open-source baseband, and they're much smarter than me =)

Well, I see it as a fantastic place to play. I look forward to digging into it myself.