Use this website to create an APN (Access Point Name) to access data on your phone. If you switched to a pre-paid carrier because its cheaper you may be having trouble getting your phone unlocked. This website is free and will create an APN for any phone, and you will be able to use the data purchased on your airtime card, without dealing with your carrier to unlock your phone. If you reset your phone settings you will have to create the APN again using this website. Also works iPhone.