Difference Between CDMA and GSM Cell Phonesby Matt Skaggs
As cell phones have improved, they've become more and more powerful, and, potentially, more confusing. If you're interested in purchasing a new phone, looking over phone terms and specifications can be intimidating. Fortunately, while the technology behind CDMA and GSM cell phones is complicated, how these differences affect is easy to understand.
CDMA (Code Division Multiple Access) and GSM (Global System for Mobiles) are the two main types of cellular technology available. They operate on different radio frequencies, meaning that a cell phone with hardware compatible with one type of technology is incompatible with the other. A GSM cell phone, for instance, cannot connect to a CDMA network or even identify the presence of a CDMA network. Call quality is not inherently better or worse for either type of these technologies; carriers are largely responsible for the quality of calls and data speeds.
Carriers use one or the other type of technology. Among major carriers in the U.S., GSM is used by only AT&T; and T-Mobile. CDMA is used by Sprint, U.S. Cellular, MetroPCS and Verizon. In Europe, all carriers use GSM, meaning that many GSM phones in the U.S. will work in Europe with the proper plan, but you should always ask your carrier about options while traveling.
Cell phones, like carriers, can be only GSM or CDMA, not both. While the cell phone type information is listed in the phone's description, the easiest solution is simply to see what phones your carrier offers or what phones are available for a carrier you're considering. Additionally, GSM networks support the use of unlocked phones, which require only that you use a SIM card with a current cellular account. This means you could buy an unlocked phone and use it for AT&T; or T-Mobile. CDMA networks don't support unlocked phone technology, so if you want to switch a CDMA phone to a different CDMA carrier, you should always check with that carrier beforehand to see if that is possible.
Carriers are moving to 4G networks, which means much faster data speeds for 4G phones. However, many carriers that advertise "4G," or even "4G LTE" specifically, are not necessarily compatible with each other. This is because, although speeds are improved, many carriers still operate their 4G networks on different radio frequencies. Different 4G carriers also have very different data speeds. For specific speed availabilities, you should check information from carriers and reputable technology websites, such as Consumer Reports, CNET and PC Mag.
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