This is a guide to network unlocking a BlackBerry for free without PC software. It works on all BBOS models except the 9720 - I tested it on a 9320.
1. Check if the phone is locked. Go to Options > Device > Advanced System Settings > SIM Card (OS 6/7), Options > Advanced > SIM Card (OS 5) or Options > SIM Card (OS 4). Type mepd and several items will appear. If 'Active' or 'Enabled' appears next to 'Network', it's locked.
2. On a PC, follow this guide, writing down the IMEI.
3. Choose OS Engineering Screens > Device Info. Scroll until you see the MEP and write it down.
4. On a PC, click here, create a CrackBerry account and follow the PM instructions. Don't download the software!
5. When you get the unlock key, go to the SIM Card menu (step 1). Type mepe or any of the codes here, then enter the key. If 'Code accepted' appears, the phone is now unlocked!