how do unlocked cell phones work?

An unlocked phone is one that you can use on your provider's network simply by inserting your SIM card. If you get service from AT&T or T-Mobile, you will be provided with a SIM card that uniquely identifies you as a subscriber. SIM cards also have some storage capacity for frequently-dialed numbers and some settings. Not all phones are SIM capable. Sprint phones, which do not use GSM, do not have them. You can shop for unlocked GSM phones online, including places like amazon.com, and optionally buy a service plan along with them, or just buy the phone and get your service from the provider of your choice. <a rel="nofollow" href="http://www.amazon.com/cell-phones-service-plans-accessories/b/ref=sv_e_5?ie=UTF8&node=301185">http://www.amazon.com/cell-phones-service-plans-accessories/b/ref=sv_e_5?ie=UTF8&node=301185</a> They are not necessarily more expensive than the phones you can buy from a cellular service provider; in fact, buying an unlocked phone is an excellent way to upgrade ...  more

Most wireless providers lock in the phones they sell so you can only use them on their own network. An unlocked phone will work on any network after you insert your own sim card (from your old phone). Buying an unlocked phone enables you to get a much nicer phone, but you will most often pay full price for it.  more

Unlocked cell phones means you can use other carriers phones or generic phones on your network. For example, an unlocked ATT phone can be used on the T-mobile network, you just throw in your SIM card. So you do need some sort of agreement with some cell phone company, which usually means a 2 year contract with a monthly bill. Att and T-mobile use the same sort of network, GSM. This process doesnt work with the other kind of network, CDMA (Verizon, Spring, Alltell, etc). These networks do not have SIM cards.  more