nikseeth··on Sniffing GSM Traffic with HackRFI put up a detailed guide going from zero to scanning a Control Channel a while back with pertinent commands, etc: http://blog.nikseetharaman.com/gsm-network-characterization-...
nikseeth··on GSM Network Characterization Using Software Defined RadiosYeah, it's awesome stuff. Listening to the HAM guys on the local repeaters occasionally makes for some entertainment.