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Global System for Mobile Communications (GSM - Origionally from 'Groupe Spécial Mobile')
The Global System for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. GSM service is used by over 2 billion people across more than 212 countries and territories. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs significantly from its predecessors in that both signaling and speech channels are digital call quality, and so is considered a second generation (2G) mobile phone system. This has also meant that data communication was built into the system from the 3rd Generation Partnership Project (3GPP).
The key advantage of GSM systems to consumers has been higher digital voice quality and low cost alternatives to making calls, such as the Short message service (SMS, also called "text messaging"). The advantage for network operators has been the ease of deploying equipment from any vendors that implements the standard.[3] Like other cellular standards, GSM allows network operators to offer roaming services so that subscribers can use their phones on GSM networks all over the world.
Newer versions of the standard were backward-compatible with the original GSM phones. For example, Release '97 of the standard added packet data capabilities, by means of General Packet Radio Service (GPRS). Release '99 introduced higher speed data transmission using Enhanced Data Rates for GSM Evolution (EDGE).
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