When you place a new or a existing SIM card from another phone provider into a different cell phone and it asks for a Security Code
You can unlock your phone through online
(unlocking service is not free)
please follow this steps
1)goto
http://www.unlock-zone.com2)register a account(it is simple only your name,email id and password)
3)select your phones manufacture(blackberry,nokia,samsung,lg.................)
4)select your phones model
5)select your country
6)select your service provider
7)enter your phone IMEI (press *#06# to get IMEI)
8)complete transaction
9)your unlock code get within few hours