Sunday, 25 November 2007


GSM or CDMA? We often hear GSM and CDMA technologies being used as one of the main marketing points for mobile phones, but how many of us actually know what these technologies are? And why would we choose one over the other?

For a start, I will give a brief overview of the two technologies:

Short for Global System for Mobile communications, GSM is the most widely used cell phone technology in the world and is though to have somewhere between 75% and 85% of the market share. It was first launched in Finland in 1991 and is currently available on more than 690 mobile networks in over 200 countries. GSM phones support SIM cards, which give the phones owner great freedom with global roaming and changing to other phone operators. Security is a main feature of GSM technology and it uses several cryptographic security algorithms.

Short for Code Division Multiple Access, CDMA is a digital cell phone technology used in second generation (2G) and third generation (3G) mobile phones. It is currently a very popular network in Asia Pacific and North America with popularity starting to grow in other parts of the world. CDMA phones do not support SIM cards, the account information and the owners address book and details are programmed into the phone. CDMA is a form of multiplexing that allows multiple signals to exist on the same channel, optimising the available bandwidth.

Which technology should you choose? If both GSM and CDMA networks are available in your area, your decision should come down to data transfer speed, global roaming and whether you are likely to change your phone all that often.

Data transfer speed
CDMA currently supports data transfer speeds up to 2Mb/s thanks to EVDO (EVolution Data Optimised) technology. This is currently superior to what GSM can offer although I should mention that GSM is fast catching up.

Global roaming
GSM is the obvious winner here due to the ability to change a phones SIM card for local providers.

Changing phone
If you are likely to change phone quite frequently and would like to keep your number and personal contacts, GSM would again be obvious choice due to the ability to change SIM cards.

Another factor may be the quality of your local networks. If you have a choice between GSM or CDMA, it may pay to do some research and see which network has the best coverage in your area.

CDMA Development Group Website
GSMA Website

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