How much would it cost me to unlock an iphone 4 in the UK?

I've bought a second hand iphone 4 and its on the orange network, i need to have it unlocked so i'm able to but my three sim card into it? I don't want to spend that much?!

The original owner can ask their network to get it unlocked - it's usually free for contract phones, possibly £15 for pay-as-you-go.

iphones do not use an unlock code or anything like that, Apple send an update to the phone via itunes which modifies the firmware in the phone.

There's no other way of getting one unlocked than via a phone service provider.

If the original owner will not do it, try getting a pay-as-you-go SIM for Orange, and ask them to link the phone serial number to your account.
There's a possibility then that you can request an unlock via that company.

They will charge you 20.42 and can take up to twenty days depending on the phone and who you talk to there number is
150 from the handset or 07953 966 250

http://www.moneysavingexpert.com/phones/unlock-mobile-phone