Then once you have successfully managed to transfer your # to your new s devices sim card you can pop out the sim card and pop right back into your desired device! You'll find that 9/10 your sim card will automatically work! Then you can pop the original sim card you activated first back into your other device. bottom line make sure that when you go online you go click on switch devices then ? you put the imei of the dummy device and your new sim cards ICCID that you'll will need to input in the online settings to in order to successfully transfer your # or services to your devices new sim card. Then on the prepaid website its pretty simple to log in to your phones original account that has your original # and basically you can transfer your phone # to the phones new sim card that your activating! Very simple! As long as its a fresh sim card that's never been used and that piece of crap device is not flagged, already being used, or currently registered with someone else's account that you are not able to access will hinder you from activating any services on on that device or any device for that matter that is still attached to any account having any unresolved issues. You don't need to keep asking customer service agents for help! You just need to activate any random device of the carrier you want, then take that sim card out and pop and pop it into your desired device! It will automatically work! Then at this point you might be able to transfer your original phone # by purchasing a new AT&T sim card kit, then popping then sim card into any random device or the same carrier that's not being currently used.