Happy birthday, dear Global System for Mobile Communications! 20 years ago today, on July 1 1991, the world's first GSM call was made by Finnish Prime Minister Harri Holkeri. The historic call used Nokia gear on GSM's original 900MHz band. Today GSM is all grown up and ruling the world -- connecting 1.5 billion people in 212 countries and serving 80% of the planet's mobile market. GSM gave us a number of firsts. It was the first fully digital cellular system using TDMA to cram more information into less spectrum and provide better sounding, more reliable calls using less power. It introduced the Subscriber Identity Module (
