Blackberry 8800 / 8300 Phones

1 Insert accepted (carrier) SIM card
2 Power on the handset (wireless option should be off)
3 Scroll to Options and press the trackwheel
4 Select Advanced Options
5 Scroll to SIM Card and press the trackwheel
6 Type MEPD (NOTE: You will not see any text appear on the screen while typing MEPD)
7 While holding the Alt key, type MEPE
8 You should be presented with a prompt "Enter Network MEP Code". Type in the unlockcode and press in the track wheel / jog dial to confirm
9 Press the Enter Key

Voila!
To purchase the 'unlockcode' for your phone, select the corressponding listing on the right side of this page.