You can contact the network provider and sometimes they offer free unlock if all their terms and conditions are satisfied.If they deny,the remote unlock service would be a better option because, you need not give your mobile to someone else nor do you have any chance to enter the wrong unlock codes. To get such an unlocking service for your iPhone 4 approach Unlocking4u.com and by submitting the country and network to which the mobile is locked to you will be able to remove the restriction from the respective network. This will be a permanent unlocking solution.
