T-mobile to go is a very convient service that I enjoy very much,basically they allow for you to have a phone without actually signing a contract. This is also useful when you need a phone in case of an emergency. All it requires is a T-Mobile pre paid sim
card and you can buy minutes at your local convienent atore and fill them up whenever you need. You just call the number on your receipt and enter your code and your good to go with $5,$10,$25,$50, or $100.
This is also useful if you have a Sidekick ...