More of a reference for myself, but it is relatively easy to network unlock your Blackberry for free using this simple guide and a few handy tools.
1. Follow this WikiHow.com guide
http://www.wikihow.com/Unlock-Your-Blackberry
2. Get your MEP code from your phone
This is the network code that your phone is currently using / locked to – luckily there is a handy tool to read this for you by connecting your phone to your computer / laptop
http://www.mobileunlocked.com/blackberrymep.asp
3. Get your IMEI number from your phone
Simply dial *#06#
4. Generate your ME2 unlock code
Using the codes from Step 2 and Step 3 you need to download a copy of BBCalculator (normally named BBCalculator.rar) to calculate the ME2 unlock code
Here’s were I got mine
http://www.4shared.com/postDownload/7y7gB0x0/BBCalculator.html
Follow the guide in Step 1 to access the hidden Blackberry menu to enter your ME2 code – and then as long as Step 2 and Step 3 are correct you should be completely unlocked