How to unlock my iphone 3gs for free?

Hi what it is is i have a iphone 3gs on o2 its a phone i bought of a friend after its 2 years contract ran out but o2 are refusing to unlock it. So is there any free online or downloadable software i can use to unlock my phone for FREE £0.00

Added (1). I'm wanting to use this phone on vodafone as thats who my contract is with

Added (2). I'm not wiling to pay at all wether it is or not safe

Added (3). O2 are refusing to unlock it for free

Why don't you use a giffgaff sim in it, giffgaff is run by o2 so the sim should work without unblocking it google giffgaff and go to there website and you can order a free sim

Free unlocking service is not possible for your iPhone. It's only available for old model phones.free unlocking method is not safe.So, better you can get paid unlocking service. You can unlock your Apple iPhone 3gs using Remote unlocking service at http://www.simpleunlocking.com/apple-iphone-3gs/rs16wp9/ here they help you unlock your iphone using latest version of iTunes software. And you can get free unlocking instructions from http://www.mobileunlockguide.com/apple-iphone-3gs here they will help you step by step instructions about how to unlock your mobile.

Really the only way to get a phone unlocked for free is to have the carrier its locked to… Unlock it. Otherwise you'll have to purchase the unlock online… Which won't be free: http://gsmunlocklabs.com/unlock-iphone/