Erika October 28, 2015 at. 12:00 I wanted to buy a new iPhone I currently have the 4 who used to be my dads, he has unlocked it and I have it with wifi. If you want to trade a service for some reason, like if you have a poor mobile service in your area, you need to buy a new one if your phone is locked. I actually interested in getting a mobile phone abroad (I currently in Laos), buy it back to the US, and use it with one of these monthly prepaid SIM card phone packages. With an unlocked phone, simply use another SIM card (the small piece in these major credit card size holders). Not all companies are out to annoy their customers, but stories about people who, after a short international trip to a bill of more returning a thousand dollars is anything but unusual. If you want to make the most of selling this old device or if you want to give it to someone who is not necessarily the same vendor as you, your unlocking is the best way to get the full value of Text and Data in most countries over The whole world is not offered by any other major provider - but depending on how fast you moving (ie how many SIM cards you have to buy), the T-Mobile plan is probably even more expensive. You probably have to remove the backplate to see it, and on many phones, you must also remove the battery from the device, provided that the phone has a replaceable battery. Fortunately, there is some kind of work for this problem, and it is provided by the smaller providers who are increasingly competing with the major national carriers. But if you want some of them, you can almost always find them on Google Play for installation, provided you pay for service on one of their networking. Apple Iphone 6 16gb Space Gray Unlocked Gsm on this page.