I remember something similar, it was a presentation given at CCC in Germany. Tried searching for it on their YouTube channel, just to discover said channel was terminated for breaking YouTube ToS?!

That's really sad, their channel had videos of all the past talks from the CCC, an amazing resource that's now gone.

I think this is the one you might have been talking about: https://www.youtube.com/watch?v=lsIriAdbttc

If it's not that one then it's probably one of the "Running your own 3G/3,5G/GSM network" talks.