What is the 8310 unlocking code?
If you are looking to unlock your phone so you can use it on most GSM providers, then you would need the unique unlock code for your phone. The unlock code is calculated off of the IMEI #, model of the phone and the carrier to which the phone is locked to.
There is a website called, Free unlock. This site will give you a code to unlock a Blackberry 8310. After getting a code, select options and then advanced options. Click on SIM card. Then hold the alt while typing MEPD. The screen will change, then press MEP2. You will then have to enter the unlock code. Press trackball and your done.