I'm a little confused as to what you are trying to do, but when you change blackberry devices with t-mobile you have to update the device pin, at times. There are times when the system doesnt auto update it and you have to change the device manually. A rep can do it for you if you call or you can do it yourself.
Just log into mytmob, go to the Connect and Share option, then Configure E-Mail, and click on Change Device. All you have to do is enter the new IMEI and Device Pin and update. After that, go to Service Book section and Send them.
Let me know if that helps or please clarify what your trying to do. I'll be more than happy to assist you.