I recently brought a Sony Ericsson Vivaz off my friend, I am currently on O2 but the phone is a T-Mobile sim only. I do not want to change service provider but I wish to unlock my phone so it can take any sim, or atleast be unlocked so I can use my O2 sim. I'm not prepared to pay to unlock it as I know many people have unlocked their phone for free and I don't see why I should pay. The IMEI number is 012451005325247 if anybody is able to help but needs the IMEI number. Thanks to anyone who helps.