CEO of Fairwaves here. Just want to slightly correct here. We indeed started with OpenBTS, but we switched to Osmocom years ago for a variety of reasons including better code quality and proper community development model. And while we're not the original authors of Osmocom either, we added SDR devices support to it, polished osmo-trx to a state it can be used in production, wrote first GPRS implementation, etc, etc. Right now Osmocom is a thriving community with several companies actively contributing, so it's moving faster than any other open-source GSM project out there. There will be more really exciting news about Osmocom soon - keep your eyes open. So if you want to go to the source - I suggest http://osmocom.org/projects for real open-source. Btw, no one stops you from using osmo-trx/LimeSDR with YateBTS if that's what you prefer. That's the beauty of choice open-source gives you.