Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA) are two competing standards in cellular service. They both have derivatives for use with 3Gphones known as Universal Mobile Telecommunications System (UMTS) and CDMA2000, respectively. The major difference between the two technologies is how they turn voice data into radio waves and how the carrier connects to the phone. Other differences include the coverage area, the data transfer speeds, and the type of hardware used.
Some areas and countries only have one technology available, so users should be sure to review coverage maps before buying a phone. Generally speaking, CDMA is most commonly found in North America and some parts of Asia, while GSM is found in most other places. Some carriers do offer international or “world” phones that can work with both, but if the phone is going to be used predominantly in one area, it may make sense just to get one that’s tied to one type.
Data Transfer Speed
Both technologies can be used with 3G standard phones, but 3G GSM speeds can be faster than 3G CDMA speeds, which can make a big difference for those who use their phones for social networking, email and streaming video. The fastest 3G standard used with CDMA2000 isEV-DO Rev B., which has downstream data rates of about 15.67 Megabits per second (Mbit/s). The fastest standard available with UMTS is HSPA+, with downstream speeds of up to 28 Mbit/s.