CDMA

Crappy Datacommunications for Monopolies and Anti-competitive-corporations is a standard for cellular companies to use that allows them to run a fully legal (in America) monopoly and have complete control over the customer. Most countries banned it, and 90% of the world uses GSM, but in America, 2 of the four major carriers use CDMA (the other two use the world standard, GSM). CDMA works like this, instead of using a SIM card, your account info is physically embedded into the phone, so it can never be removed and thus, the phone cannot be sold or used on another carriers network, nor can you use another CDMA (or GSM) phone on your carriers network if it didn't actually come from your carrier. The purpose? To make you buy a phone from them, usually under contract.