What does GSM mean?

It is the flagship brand of China Mobile Communication. GSM is a mobile phone package service, which allows users to use the same mobile phone number at home and abroad and can realize the function of international roaming. This package provides various preferential policies and value-added services, including unified call charges for long-distance calls, local calls and roaming calls, and all called calls are free. GSM can use telephone, SMS and Internet services all over the world, covering almost all countries and regions in the world.