I recently purchased a used jailbroken iphone 3rd generation. i have tmobile service and was told switching the phone from att to tmobile would be an easy process. It has turned out to be everything but. i put my tmobile sim card in the iphone and reconfigged several different ways as are shown on various credible websites. Ive tried changing the network config apn from internet2.voicestream.com, epc.tmobile.com, and wap.voicestream.com multiple times. Each time i change all 3 apns. Ive tried changing just one, used all 3 codes, disabled wifi/3g, and on each power on i get that no network is found. I always make sure to leave data roaming turned on. the phone is in fact jailbroken. It has a black background, jailbreak software, etc. Is the phone possibly not unlocked? Im not sure what my issue is, but any constructive input would be greatly appreciated.