These days when you get mobile phones you would see that most of them are generally locked up to catch a certain network provider. Obviously when you are making a mobile cell phone purchase you would specify what network you are working on. But in due course of time you want to switch to a different service provider. There might be many reasons for that. You might not be happy with your current network service. You might be moving to a place where there is a better coverage for another network provider. That is exactly when unlocking the iphone 3GS is needed.
Of course in case you were not using a very high graded phone, you could have easily exchanged the phone. But in case you are using a phone like the iPhone 3GS, you know that it is not an easy task to part with such a phone. Now when you need to switch the service provider, iPhone 3GS unlock becomes a big hassle. It generally requires the skill of a computer engineer. But not anymore! Now with the development of new software you can unlock your phone all by yourself. It would just be a matter of 10 minutes.