If I buy a T-mobile contract free phone, can I use it in China with Chinese SIM card?
Also, can I use AT&T sim card in the T-mobile contract free phone?
iPhone 6, iOS 8
Hi there czjjj_233,
According to the articles below, it looks like you will need to contact T-Mobile in either situation.
iPhone and iPad: Using cellular networks while in another country
Many carriers offer international voice and data plans. Always contact your current carrier for details about international-roaming countries, SIMs, rates, and policies before you travel to another country. While you may not need an international plan to use voice or data roaming on your iPhone or iPad, your carrier may charge additional fees or higher data rates if you don't have an international plan.
-Griff W.