Depending on your device, you may have trouble updating your PRL to one that will allow you to connect to the 800 MHz bands if you're not running a stock based ROM. I don't think it's possible to update a PRL from CM 10.1 on a Sprint GS3. If I'm not mistaken, one must backup your current setup, flash a stock ROM, do your PRL & profile updates, and then restore your nandroid backup. I don't think you can get the right PRL if you sit on a CM based ROM all the time ... at least not with a GS3. Not sure about other devices.