Sprint has a good retentions department, they usually will bend over backwards to sign u to another 2 year contract, the trick is to come up with the plan you want, then do some research and see if any other companies have anything close to it. If you call after your current contract is over or close to expiring, they will try hard to meet your request. Always make sure to ask for free-roaming if service is an issue. The higher your monthly bill, the easier it is for you to get ridiculous credit towards a phone upgrade.

