Why unlock your Blackberry? Because you won’t be tied down just to one network; you can pick and choose what network suits you best. Also when you are abroad you wont have to pay those ridiculous roaming charges, you will have the freedom of choosing what sim card to use in your phone.
What is a service provider (SP) lock? This is used by the networks to ensure that your phone will only work on one network; the one that you originally bought your phone from. If your phone is SP locked then it will not accept a SIM card from another network be it UK or abroad. Unlocking is the process of removing the SP lock so that it's possible to use other SIM cards in your phone.
Prices to unlock a Blackberry: