This is a short survey of free and open source tools for GSM network hacking.
"The attack on the A5/1(http://reflextor.com/trac/a51) is a reimplementation of the attack by THC, which was done in early 2008. Our approach differs slightly, as we use more common hardware to generate the tables, namely graphics cards with GPGPU capability and attempt to build a distributed infrastructure of nodes where each node donates both a small portion of diskspace for a part of the table and some kind of fast hardware for the generation of and lookup in its own table. We also took this project as a motivation to design and code a general purpose TMTO library."
"Available GSM analyzer cost a shitload of money for no good reason. Our goal is to build a GSM analyzer for less than $1000(http://wiki.thc.org/gsm)".
"AirProbe(http://airprobe.org/) is the new home of the former GSM-Sniffer project. The goal is to build an air-interface analysis tool for the GSM (and possible later 3G) mobile phone standard. The prime motivation is to learn the details of the technology, help people who develop other open GSM technology (like OpenBTS, OpenMoko?, BS11/OpenBSC and others) and demonstrate the insecurity of the current standard".