unlocking blackjack

How do I unlock a Blackberry Pearl 8110 and BlackJack II
my cousin just bought two brand new phones. one is the BlackBerry Pearl 8110 and the other is a BlackJack II. Both phones are AT & T, the problem is that my cousin has a service with T-Mobile. How can unlock these phones for use T-Mobile? Need to talk with AT & T or T-Mobile? Is this still possible?
so you can unlock through IMEI unlock code. ATT could give you the unlock code, but I think it fair to change the company after the purchase of 2 phones at a price …. most likely not. Unlock IMEI is the best way to unlock the phone. Your IMEI number is a unique 15-digit number used to identify your phone. You can display your IMEI typing * # 06 # on the phone keypad. The IMEI is also printed on the back of the phone, usually printed on a label underneath the battery.
Blackberry Pearl Unlocking