CDMA and GSM
One of the reasons cell phones are so complicated in the U.S. is because competing technologies are used to deliver 2G and 3G signals. Verizon Wireless and Sprint use CDMA networks, while AT&T and T-Mobile (which are in acquisition negotiations at the time of writing) use GSM. Regional carriers vary, but many of them use CDMA.
There’s no huge advantage or disadvantage between the two approaches. The speed is similar for both technologies. Aside from their incompatibility with each other, you’ll notice a few other differences:
- GSM carriers use SIM cards. These are tiny cards that carry your identifying information for the network. If you switch devices, you just put your old SIM in your new device.
- CDMA carriers don’t use SIM cards ...
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