What is the difference between PDA devices sold by multiple cellular carriers? What is the difference between GSM and CDMA cellular phones/PDAs?
Each cellular/wireless carrier investigates and certifies PDAs and SmartPhones for use and sale on their network. Often times, one carrier will get an exclusive agreement with a PDA manufacturer for 90 days prior to any other carrier being able to also sell the same device. Sometimes a carrier changes one or two features of a PDA before selling it so you shouldn’t assume the same device as the exact same specifications between different carriers. While many PDAs or SmartPhones are sold under different brand names and different carriers, one of the keys to determining the right carrier and phone for your needs is that cellular technology in use. Without going into a “history of cellular phones”, most modern phones in the U.S. are digital and use GSM or CDMA technology (with the exception of Nextel which uses a proprietary iDEN technology and thus their phones/PDAs cannot roam onto other networks). Some cellular providers (including AT&T and Cingular) exclusively used TDMA technology but
