The new iPhone X series—the XS, XS Max, and XR—are the first iPhones to ship with dual SIM tech capabilities. This wasn’t enabled out of the box, but came with the yesterday’s 12.1 update. Here’s what that means.

For dual SIM support, the new iPhone X series phones use a traditional SIM tray for its primary number and an eSIM for the secondary account. While we have a deeper explainer of what that means here, the long and short is that you can’t just pop a pair of SIM cards in your phone and have it work.

Instead, your second carrier needs to support eSIM tech and you need to set it up yourself. The good news is that it’s stupid-easy to set up your second carrier. Here’s how.

Note: The primary carriers uses the traditional SIM slot. Only the secondary carrier can use the eSIM slot, so if you only have one carrier then you don’t need to do anything. It’s also worth mentioning that this isn’t yet available on Verizon—more info on that here.

First, jump into the Settings menu. From there, choose the Cellular option.

Tap on Add Cellular Plan, which will immediately open a QR scanner. If your carrier offered a QR code, scan it here. All the pertinent information will be added instantly and you’re good to go.

If you don’t have a QR code, however, you’ll need to enter this info manaully. Tap the Enter Details Manually button at the bottom.

All the information needed here should be provided by your carrier—if you’re missing anything (save for the Confirmation Code, which is optional and may not be provided) you’ll need to give your carrier another call to get the details.

The SM-DP+ Address is basically just account info that connects your phone to the carrier, and the Activation Code is sort of like a password that will let finalize the connection.

Once the proper details have been entered, the connection should be established. Done and done.