Your Mobile’s Lifeline – GSM

With blog 3

Your mobile phone is great. It let you take pictures, record videos, remember things for you, play games, watch films – the works! But it won’t let you make a call if it can’t catch the signal.

So what is this signal? In simple terms, it is a radio frequency wave that travels wirelessly from a transmitter and is received by the in-built antenna of your mobile phone. Global System for Mobile communication (GSM) is one of the cellular technologies which digitally encodes and routes electromagnetic radio waves. It is the most widely used mobile telephony system around the world.

There is a reason for that. Earlier technologies transmitted data in the form of analog signals, making voice data susceptible to prying. GSM is digitally created using Time Division Multiple Access (TDMA) system in 1991. GSM digitizes and compresses the data, making it more secure and enabling efficient use of the available bandwidth. Apart from encrypting your voice signals, it provides more security by giving each receiver (mobile) a subscriber identity module (SIM), among other features.

Subscribing a SIM identity also gave the mobile industry a huge boost because subscriber identity was not linked to the mobile handset, allowing users to switch phones while retaining the same digital id!

By inserting a SIM into your phones you become part of a GSM network and gives you the ability to connect with anyone. Our surrounding is divided into different cells and each cell has a base station covering a specific area. All phones in an area receive the signal in their phones. How well a phone receives the signal depends on many factors like distance from the base station, disruption in signal’s path etc. This is represented by the signal bars on your phone – which go blank in areas far away from a base station!  This is where Omoco’s wireless mobile technology, in a box, allows you to set up your private GSM base station and enjoy seamless connectivity.

Of the many advantages that GSM technology has, the most significant one is that it allows better coverage by allowing GSM carriers across the world to tap into each other, enabling users to make calls outside the area of their home base, at nominal rates!

How do you ‘have a chat’?

Components involved in a call – Your mobile phone, your friend’s mobile phone, Base Transceiver Station (BTS), Mobile Switching Center (MSC).

When you dial your friend’s number, your phone’s network connects to the nearest BTS to pick up the strongest signal. This tower/BTS is connected to a MSC.  Once the strongest signal of the nearest tower or BTS is picked, the phone sends an originating message. This message includes your number, your electronic serial number and your friend’s mobile number.

A verification process is then undertaken by two types of servers – the Home Location Register (HLR) and the Visitor Location Register (VLR). The MSC sends a request to the HLR to check details of caller (you) like account balance, area of calling etc. If you pass the verification HLR sends an acknowledgement to the MSC. Else if the verification fails, in case of low account balance for example, then the call is disconnected.

After receiving a verification, the MSC requests the VLR to check details of your friend’s number to know if both caller and receiver fall under the same or different MSC. The HLR acknowledges and the BTS sends a channel assignment message to your phone to tell it where the conversation will be. This begins the call. When they say ‘hello?’ – the whole process is repeated backwards, All in the blink of an eye!

So ensure your phone is fed a strong signal!