Hello my partners dad just got an iPhone 3GS what works with o2 but when I put in an orange sim it won't show up signal or anything but on available network In setting have o2 orange and vodaphone.
Will the phone need to be unlocked or will I have the change the cellular data settings ect?
it's locked to o2! All it means when you see Vodafone, Orange and O2 etc is that those networks are near by. This is so you can still call 999 if you have no signal (as it will use the others)