Your device locked to its network provider?
If so you have a few options available to you.
Vodafone offers free unlocking on all their devices. Please visit their website to unlock your device by clicking here
O2 Offers free unlocking if your meet their criteria. Otherwise you need pay them a £15 fee. You can find more information by visiting their website by clicking here
EE, Orange, & T-Mobile are a bit more complicated. They are now all under the EE group. EE will charge a fee depending wether you are an Apple customer or not. The fee is also depended on a few other factors. More information can be found here.
However if you prefer we can do it for you for a small fee.