RF exploring is the reference website about radiofrequencies and mobile network hacking.
GSM, GPRS, EDGE, UMTS, HSPA, LTE, you name it.
It also carries many informations about how to build a functionnal IMSI-catcher.
An international mobile subscriber identity-catcher, or IMSI-catcher, is a telephone eavesdropping device used for intercepting mobile phone traffic and tracking location data of mobile phone users. Essentially a “fake” mobile tower acting between the target mobile phone and the service provider’s real towers, it is considered a man-in-the-middle (MITM) attack. The 3G wireless standard offers some risk mitigation due to mutual authentication required from both the handset and the network. However, sophisticated attacks may be able to downgrade 3G and LTE to non-LTE network services which do not require mutual authentication.