Unlock an iPhone 4S on tmobile in the uk?

Can some one help me unlock my iPhone 4S that is on tmobile so I can put my other sim in the phone any comments would be helpfull

You are going to have to pay for this service and it costs pretty high with the iPhone. I would suggest you google for phone unlocking services in you're local area and then get some quotes. But be warned with the iphone it can cost anything from £40-70

Make sure that you are already out of contract before you unlock your phone. If you are already out of contract, you can check the process here http://jailbreakhome.com/iphone-factory-unlock.