As above, I recently bought myself a new smartphone. I gave my old one to my son's girlfriend, thinking it would be simple for her to use. I did not realise I had to unlock it, as she is on a different network. I have found that I can unlock the phone using an online app (I'm with O2) but am a little foggy as to what this will do. Basically I don't have the old phone - if I use the app to unlock the phone, which one does it apply to - the old one or the new one? I don't want to go through the process and find I've messed with the new phone. Help please!