全球移动通信系统（GSM）是一种数字移动通信系统。GSM手机具有通话质量好、噪声小、抗干扰能力强、保密性好等优点，目前已经在世界上许多国家和地区使用，在我国，中国电信和联通公司也先后开通了GSM系统。GSM是一种多业务系统，为用户提供了功能较强的通信业务平台。GSM系统 Global System for Mobile Communications (GSM) is a digital mobile communications system. GSM handsets have the advantages of good call quality, low noise, strong anti-interference ability and good confidentiality. At present, GSM handsets are used in many countries and regions in the world. In China, China Telecom and China Unicom have also launched the GSM system. GSM is a multi-service system that provides users with a powerful communication service platform. GSM system