What do the initials GSM stand for?

Global System for Mobile Communications.

What is GSM?

GSM is an open technology that offers high quality and clarity in voice calls. GSM technology offers some of the widest ranges of services in the world today. It also offers the highest level of security against cloning of any digital standard. This means that calls are scrambled so that no one can eavesdrop on your conversations. GSM accounts for over 70% of the world's digital market and 64% of the world's wireless market.