Meanwhile the intelligence agencies of the world siphon up signals like hungry hungry hippos because SDRs are cheap and ubiquitious, when ten-ish years ago they were poorly documented, expensive, and the encryption schemes used strong enough using 4g over wifi was a very practical security decision.
Here's an old talk that references someone's deadname with good technical information:
https://www.youtube.com/watch?v=DU8hg4FTm0g|
And a more recent talk on similar subjects:
https://media.ccc.de/v/31c3_-_6249_-_en_-_saal_1_-_201412271... |
https://berlin.ccc.de/~tobias/31c3-ss7-locate-track-manipula...
(Apologies to Kristin, if they see this: I had trouble locating JUST the slides, not audio or video, of the DC18 talk or I would have simply linked the slides.)