It can be much less expensive to purchase an iPhone 3g from a third party provider or an online source such as ebay. But to take advantage of lower prices you will have to know how to unlock an iPhone 3g. This is not a complicated procedure, but it will take a little bit of planning and time.
The first thing you need to do is make sure that the iPhone’s firmware is up to date. Then connect the iPhone 3g to the computer using a USB cable or a Firewire. iTunes should open automatically and begin to sync with the iPhone.
You will need to download a software program named Blackrain onto the computer. Then you will need to transfer the software directly to the iPhone. Then connect the device to the computer when you are prompted to do so. Double click either the DMG or EXE file to run the program. When it runs you will click on the “make it rain” button when it comes up. It will take a little while for it to reboot and then you should disconnect it from the computer.
Now run Blackrain on the iPhone and make sure that you are in a place that there is a wireless internet connection available. Then tap the new icon that was placed on you iPhone’s desktop. Choose Blackshow and then tap “install.” When it is done you can close the dialogues out. Now you should be able to put any SIM card in the iPhone and use it with any carrier.