Will the iphone 6 work out the usa?

My cousin went to usa and i want to buy an iphone from usa because its much cheaper however he went to apple store or t-mobile and they said that if he want the iphone unlocked he have to turn it on for 40 days in the is and then it will be unlocked but I've seen on the Internet that people buy it and before turning it on they remove the t mobile sim and the put there sim and it works fine so who's right t mobile or people who tried that?

When you buy a phone from a carrier such as tmobile, etc it will be locked to them and will not access another network. If you have been with the carrier for a while, they will unlock it for you if you say that you need to travel international and want to use a local sim card. It is possible that a phone shop in another country can unlock it, but not guaranteed.

The iPhone 6 is not sold unlocked, in the way you want it, as of now. Should be by late November (as is usually the case) in the US. Other countries have it like that since the launch though.

That's coz you're not a resident of US, you won't get the phone with contract. So get the factory unlocked iPhone 6, they're cheaper than other countries too. If you need need unlocked iPhone 6 without waiting long and cheaper, mail me.