GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation (or “2G”) digital cellular networks. Developed as a replacement for first generation analog cellular networks, the GSM standard originally described a digital, circuit switched network optimized for full duplex voice telephony. I have been a GSM-hacker since the middle of the 90ies, and GSM and cellular networks is still one of my major interests. I recently completed a GSM related masters thesis. This is a collection of my GSM related posts.