What is the difference between GSM and CDMA?
Digital cellular systems use two main competing network technologies: Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA). GSM, being an international standard, is better suited for national and international roaming, provided you own a quad-band cell phone (850/900/1800/1900 MHz). On a GSM phone your account information along with your contact list and other personal data are stored on a SIM card (Subscriber Identity Module) which is a small chip you can freely remove from your phone. When you get a new mobile device, you can simply insert your SIM card into it and it will work with your current account information and contact list. If you travel to another country, it is also possible to purchase a prepaid SIM card which you can use to avoid roaming fees. To upgrade your phone, you simply swap the SIM card in the back. The chief GSM carriers in the United States are Cingular Wireless, recently merged with AT&T Wireless, and T-Mobile USA. Multimedia messages, video, high-speed Internet access, digital camera and PDA functions can found on both technologies.