GSM Explained

Most cell phones use this mobile communication protocol

GSM brings voice waves to your phone
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GSM is the technology your phone probably uses to connect to your cellular service provider's network. In fact, as of 2018, 90 percent of all cell phones in nearly 200 countries are based on this protocol. Developed in 1982 and launch in Finland in 1991, it has overcome the formerly popular CDMA (Code Division Multiple Access) to become the de facto standard for mobile communication. It's considered a 2G (second-generation) protocol, replacing first-generation analog technology.

Where the Term Comes From

GSM is an acronym that has come to stand for Global System for Mobile, but it first was named for the group that developed it: Groupe Spécial Mobile.

How GSM Works

Physically, a GSM network consists mainly of connected devices such as gateways, repeaters, and relays (commonly called antennae). These are the ubiquitous, massive metal structures that stand as high towers. A GSM network is a cellular network; that is, it connects cells — the small areas covered by towers. Mobile devices connect to the closest cell, which in turn connects to others; this provides the communication and location services we are so familiar with.

The cellular network also supports 3G, 4G, and emerging 5G technologies, all of which carry data and provide internet connectivity. 

The SIM Card

Every mobile device is connected to and identified on a GSM network through a SIM (Subscriber Identity Module) card, which is a small chip inserted inside the device. Each SIM card has a phone number hard-coded into it, which is used as a unique identifier for the device on the network. People call and text you using this number.

GSM and Voice Over IP (VoIP)

GSM calls add a lot to the average monthly cell phone bill. Voice over IP (VoIP), however, can help cut the costs for many people. VoIP bypasses the cellular network and channels the voice call as data over the internet. This makes VoIP calls free or very cheap compared to GSM calls, especially for international calls. 

Some phones now allow you to set internet calling as the default method of voice connection and regular GSM calling as the fallback, saving money for both the subscriber and provider. Also, apps such as Skype, WhatsApp, Viber, LINE, BB Messenger, WeChat and dozens of others can now offer free calls worldwide for their users. This is causing a decline in the number of GSM calls being placed.

VoIP has not been able to beat GSM and traditional telephony on reliability and voice quality, however, so GSM still reigns supreme when it comes to cellular communications.