As far as I'm aware, it's not illegal. Though it will almost definitely invalidate any warranty/contract you have with Orange.
You own the phone, you can do what you want with it.
Cheers guys. As someone who has had the joyful experience of working for a mobile phone company I can tell you that unlocking wouldn't affect your contract as they're impossible to get out of (unless you die or pay your way out of it), but it could affect the warranty on the handset.
Having your phone unlocked is legal but your basically throwing the warranty you have with Orange out the window.It's like getting your dvd player hacked.It's not illegal but once it's done your warranty with the maker of the dvd player is void.
Mobile phone unlocking or technically called SIM unlocking is completely legal. There's no law that says you are not allowed to unlock your mobile phones and that you can only use it on the original service provider that it's with.SIM unlocking also does not void your contract with the service provider. Media URL: http://globalunlock.com/phones/ Description: