OsmocomBB – Open-Source GSM Baseband
bb.osmocom.org
bb.osmocom.org
Keep in mind however that using OsmocomBB based phone on public network without proper permission is illegal. http://bb.osmocom.org/trac/wiki/LegalAspects
Also, just to state the obvious, OsmocomBB is limited to Calypso, which is limited to 2G.
Anyway, the real question is: Can you build a 4G radio you can trust because it does little enough that it can have open firmware and driver and protocol software that takes less than 10 years to write? I think the answer is "Yes. Maybe simpler than 2G." Or at least "Much more likely than with a 3G radio."
[1] of course all feature and legal restrictions apply, so don't get too excited about "yay free baseband finally!". It's a amazing research project nevertheless, which together with OpenBSC already gave us incredible insights on GSM security. All hail Harald Welte! \o/
More about feasibility of a "OSS phone with no backdoors" - https://www.youtube.com/watch?v=ahPFCFooBv0&list=PL-s0IumBit...
I really hope the neo900 succeeds, but sending money to goldelico is generally a bad bet.
All of Goldelico customers who paid for GTA04 already received one long time ago. I don't count latest fundraiser for its new revision[1], since it will be fully refunded if not enough people will preorder to actually produce a new batch.
Also, Goldelico is "just" a contractor doing work for Neo900 UG, which is the actual entity running the Neo900 project.
But I think we're getting a bit off-topic here. #neo900 on freenode might be a better place for that ;)
Straight from the Osmocombb site: "Keep in mind however that using OsmocomBB based phone on public network without proper permission is illegal"
Another reason why GSM and its offspring(I'm looking at you LTE) blows ugly chunks.
You can, however, use the monitor mode without transmitting anything.
What the networks don't want - and the motivation for the certification - is for some device to misbehave (e.g. emit a continuous transmission) and interfere with the operation of other devices on the network.