GSM Explained


Generally speaking, GSM is of interest to anybody who would like to understand the growth of digital technology and its commercial GSM applications.

1st Generation (1G) mobile phone technology was designed for basic voice calls. The only kind of data transfer is analogue signal exchange between phones.

In the early 1980’s, European countries struggled with approximately nine competing analogue standards, including Nordic Mobile Telephony (NMT), Total Access Communications Systems (TACS), and so on.

The existing analogue mobile systems in place were totally incompatible with one another and limited to the extent of the respective national jurisdictions

Because of the shortcomings and incompatibility issues associated with analogue systems, a completely new digital solution was instituted.  A new standard, (GSM), was built as a wireless counterpart of the land-line Integrated Services Digital Network (ISDN) system.

GSM is a communication standard adopted by carriers to achieve “always on” Internet (TCP/IP) access and rich multimedia exchange between both phones and web providers

In 1982 the roll-out of this multi-national global communications standard was to focus on spectrum efficiency, international roaming, low mobile and base stations costs,

This was the real starting point for mobile technologies known as 2G (2nd Generation) where voice calls are converted into binary and transmitted in digital form.

GSM (Global System for Mobile Communication), became the most widely used mobile phone technology Worldwide.


GSM divides up the radio spectrum bandwidth by using a combination of Time- and Frequency Division Multiple Access (TDMA/FDMA)

Most GSM systems operate in the 900 MHz and 1.8 GHz radio spectrum bandwidth, Operating in the -1800 MHz frequency band provides operators virtually unlimited capacity

UMTS , HSDPA and LTE mobile technologies which are paving the way For 3 G and 4 G Services, providing higher speeds are an evolution of GSM and all phone manufacturers build their phones to be compatible with multiple network modes so whichever phone you have, it will have GSM compatibility, apart from In the US, where there are two legacy wireless technologies — CDMA and GSM — which are completely incompatible with each other. The majority of the Verizon and Sprint networks use CDMA technology, while AT&T and T-Mobile use GSM.

Sim Cards and GSM Authentication

GSM technology calls for a particular type of international mobile phone — the quad band is probably the best e.g.  Apple iPhone 5 and iPhone 4S– and a computer chip called a SIM card (Subscriber Identity Module); a SIM is the size of a postage stamp with embedded circuitry which is inserted into a GSM phone to get phone service on your GSM network, all subscriber and wireless provider information is stored on the SIM cards

The SIM card gives you a phone number and determines what features are available on the GSM network you choose.

Another of GSM’s most attractive features is the extent to which its network is considered to be secure.  All communications, both speech and data, are encrypted to prevent eavesdropping, and GSM subscribers are identified by their Subscriber Identity Module (SIM) card (which holds their identity number and authentication key and algorithm).



GSM applications