First you need to get the unlocking code which is available from the network the phone is locked to. Once you have the code you can use the procedure outlined in the link below.
23-05-2012 14:43 - edited 23-05-2012 14:44
Please be aware that excellent reource by cjlim is now a liitle out of date and you only get 3 attempts upon Nokia BB5 devices before being locked out, provided no one else has used up any goes before. Lock counter can however always be reset at Nokia Care Point if necessary.
Timing of repeated presses upon * star key are also quite critical at about one a second!
Happy to have helped forum with a Support Ratio = 42.5