I am trying to replace my 2G iphone with a new iphone 3Gs without jailbreaking it, as well as trying to minimize cost. I currently have an iphone 2G without data plan and was wondering if I could purchase a new 3Gs and cancel the contract within 30 days but in the mean time switch the sim card from the old 2G to the new 3Gs so I could use my current phone # and phone plan from my old 2G on a new 3Gs. This plan is probably flawed so I was wondering if there is a better way to get a new 3Gs without having to jailbreak it. Any input is greatly appreciated. Thanks!