GSM technology is the technology that you (most probably) and 80% of mobile users use for making calls on their mobile phones. In a way, it is the standard and default wireless protocol used for mobile communication.

GSM started back in 1982 and was then named after the group that devised it, Groupe Spécial Mobile, whence the GSM acronym. The official protocol was launched itself in Finland in 1991.It is now called Global Systems for Mobile communications.

GSM is considered a 2G (second generation) protocol. It works with cells, which is why a GSM network is also called a cellular network, and phones working on GSM are called cell phones. Now what is a cell? A GSM network is split into cells, each one of which covers a small area. Devices (phones) are then located and communicated with through these cells .A GSM network consists mainly of connection devices (gateways etc.), repeaters or relays, which people commonly call antennas – these massive metal structures that stand as high towers and the mobile phones of users. The GSM or cellular network is also a platform for 3G communication, which carries data over the existing network for Internet connectivity. GSM system was developed as a digital system using time division multiple access (TDMA) technique for communication purpose. A GSM digitizes and reduces the data, then sends it down through a channel with two different streams of client data, each in its own particular time slot. 

Dont worry if you didnt understand. Look below for a more simple approach to understanding the concept :)

GSM Simplified

Let’s look at the above in a day to day life example, consider the postal service. We want to send a letter, so we post the letter with the receiver address details and drop in mail box the postman picks it up and drop at the nearest Post Office. The office is filled with many such letter their the letters are segregated and our letter is transported to   nearby post office of the receiver location. At the receiver end the letter is given to a postman to deliver the letter to particular address thus the letter get dropped in receiver’s mail box.Let’s get into technical aspect of things the letter we want to send is actually a call we want to place using our phone the  postman is acting as a mobile tower to send the call from sender end to a base station where it is being segregated to put  on same frequency band as that of a receiver and from base station it is sent through optical cables to the network station over to receiver’s location their it is checked to be sent to the correct person in that region our call again send through signals to the tower from that to the receiver in his home. This steps occur during every call we place in a jiffy so that we actually never realize the delay.

This is a 2minutes explanation of GSM calling. Hope you understood the post:)

- Yash Hule