If you don't have a SIM card or don't want to use one, you can still use a Windows or Mac computer with iTunes to set up your iPhone. Again, if you got a new phone and you're just having iPhone X ...

How to activate a T-Mobile SIM card online You may find it easier to activate your T-Mobile SIM card on your computer as you'll skip the call to customer service by following these steps: ...

A dual-SIM setup lets you use one phone to make and receive calls and texts from two numbers. It's also super convenient and can save you serious cash when traveling. We show you how to use two ...