Its been years since I have been on the site and a lot has changed. I tried during a search for this but I couldn't find exactly what I was looking for. It seems like an obvious question so if I missed the post I am sorry and just point me in the right direction. My question is if a carrier knows if you unlock one of there phone to use on another carrier. Obviously if you get a code from them they know but if you pay for a code that works. Can they tell that the phone is active on another network?