Ya surely you can also unlock your iphone 4 from network provider then freely use it with t-mobile or any other GSM sim ...You can easily unlock it through online providers like ProUnlocking.com here they are rendering remote unlocking service to unlock all model iphone from network provider ...You first check that whether the service is available for your country and network provider ..If yes then pay for it and unlock the iphone 4 then freely use it with any GSM sim ...
