unlock

Just wondering where the cheapest place to do this is. I have a Nokia 6310i I plan on selling and it looks like it's worth quite a bit more if unlocked than left locked to Orange.

Hello everybody, My sister family will move from the US to the UK. They have iPhone 6 - Network locked to AT&T Galaxy Note 5 - Network locked to AT&T Can these phone be unlocked in the UK and if so where? (e.g. website, phone shop...) Many thanks for any help people can give.