July 1st 1991, the day the first GSM call was made by the Finnish Prime minister Harri Holkeri. The call was made using Nokia gear on 900MHz band. Today, 20 years later the GSM enables connection to more than 1.5 billion people in 212 countries. Eventually the GSM expaneded to 400, 800, 1800 and 1900MHz bands. They were followed by WDCMA-based UTMS(3G), HSPA and HSPA+ and lastly the LTE(4G) networks.
