GSM and CDMA Mobile Phone Networks Posted By : Gen Wright
For the average mobile user, the terms GSM and CDMA can get mixed up, but knowing the right network technology can help in making the right phone choice. The GSM network is by far the most popular standard for cell phones around the world, currently occupying 82% of the global market, which equates to about 3 billion people. GSM stands for Global System for Mobile communications, the "global" label standing up to a host of 212 countries and territories.
The GSM network was developed as a 2G network with data transfer in mind, and this method for exchanging data over the GSM network is known as EDGE, or Enhanced Data Rates for GSM Evolution. The GSM network was also the first to develop the SMS, or Short Message System, otherwise known as text messaging. Examples of GSM networks around the world are AT&T Wireless in the US, Vodafone in the UK, O2 in Europe and South America, and Orange in France.
One of the advantages of the GSM network is its ubiquity, which makes international roaming a breeze. However, the frequencies on which the networks can vary by country, which has lead to varying amounts of frequency support. This is denoted by the terms "dual band," "tri-band" or "quad-band." The frequency bands used for GSM are at 850, 900, 1800, and 1900 MHz. A dual band phone only combines two bands, which could be 850/1900 in American phones, and 900/1800 in European phones. A tri-band contains any combination of three of these bands, one example being a 900/1800/1900 mix. The quad band model contains all frequencies, providing the greatest coverage.
A key difference between the GSM and CDMA networks is the use of a SIM card. SIM cards, or Subscriber Identity Module cards, are used to store the IMSI (service-subscriber key) of the customer. They also are used to store contacts and text messages. The benefit of a SIM is that it is removable, so the customer can switch phones by transferring the card. At the same time it is possible to keep your phone, but swap out the SIM for a prepaid one or local card to avoid roaming and international charges. This is very useful for business or long-term travelers.
The CDMA network is a competitor to the GSM network, but while the abbreviation CDMA stands for code division multiple access, a method used in the foundation of many communication technologies, the networks around the world are actually separate entities. Some of the CDMA mobile networks are CdmaOne, CDMA2000, and EVDO. CdmaOne was the first CDMA-based network, second generation (2G), and used for voice as well as data transmission. This platform is being phased out for CDMA2000, a much faster and advanced standard. CDMA2000 is a blend of 2.5G and 3G technologies. This includes the 1xRTT standard and EVDO standard, 1xRTT being the core and EVDO recognized for fast data transfer. Examples of CDMA carriers are Verizon and Sprint in the US, Vodafone and Orange in Europe, and O2 in Europe and South America.
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