Go Back to Unlocking Codes Nokia Lumia 520 Nokia Cable Unlocking Service Step 1: Download Nokia SL3 Unlocking Server Software Download the Nokia SL3 Unlocking Server software: SL3_Unlocker.zip , You don't need to install this software. Unzip the file to your desktop ( or somewhere ) and leave for now. Download and install the Nokia USB drivers from here: Nokia_Connectivity_Cable_Driver_7.1.69.0.zip Note: Wait until the Nokia USB drivers are completely installed. Once complete, reboot your PC then proceed to step 2. Step 2: Checking the Drivers are installed and your Mobile is connected to the server. Remove the SIM card and any memory cards from your phone. Turn the phone on and Connect it to your PC using a standard USB cable. When the phone starts, make sure you select PC Suite or Ovi if prompted. The phone may ask to start without a SIM card, click 'Accept'. Allow windows to install all drivers automatically It's