What you need to know about the iPhone's new dual-sim feature

When Apple announced the iPhone XS, XS Max, and XR, the company announced that -- for the first time -- it would be possible to use two phone numbers on the same phone using eSIM technology.

What is an eSIM?

An eSIM takes the place of the small plastic SIM card your phone uses now. The advantage of an eSIM is that it's embedded into the phone, and can be programmed -- and reprogrammed -- to work with various carriers.

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Eventually, it makes sense for phone makers and carriers to adopt eSIM technology instead of having to manage the plastic SIM cards that have been a staple of cellular technology.

Which iPhones support eSIM?

Currently, only the iPhone XS, XS Max and XR support dual-sim service using an eSIM. iOS 12.1 is required.

In China, Hong Kong, and Macau, Apple released an iPhone XR and an iPhone XS Max with dual-sim card slots. So, instead of a single SIM card slot, and an eSIM, the two devices have space for two physical SIM cards.

Why add a second number?

Adding a second phone number to your iPhone can be useful when traveling overseas, where data roaming fees are too expensive. You can purchase a data plan for a local carrier, add it to your iPhone, but keep access to your standard phone number for calls and texts.

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Another use case is to have a personal phone number and a work number tied to the same device.

Or, depending on the cost of adding another line, a second line could be used to help manage potential dates or Craigslist transactions.

What about carriers?

Right now, at least for those in the US, carrier support is the last hurdle. With the release of iOS 12.1 to all iPhones worldwide, your phone is ready and able to work with an eSIM number. However, Verizon Wireless, AT&T, and T-Mobile aren't quite ready to support the feature.

Here's the current list of carriers that either offer support right now, or for the listings with an asterisk, will have support later this year:

Things to keep in mind

There are some details you'll need to navigate in order to use the eSIM feature:

• You need an unlocked iPhone to use two different carriers.
• If your main SIM is for a CDMA carrier (Verizon or Sprint), the second line can't be a CDMA line.
• Only one line can be activated with iMessage and FaceTime. The other line will still send and receive regular text and photo messages.

Setup

When you're ready to add a second line to your iPhone, you'll need to either visit a wireless carrier's store or download and install the carrier's app. If you're traveling, it's probably easier just to visit the store and talk to a human instead of trying to navigate through an app that may very well be in a different language.

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The wireless carrier will give you a card that has a QR Code on it. You'll need to go to Settings > Cellular > Add Cellular Plan to scan the code, then follow the rest of the prompts to complete setup.

Another method is to set up the eSIM using a carrier's app, which walks you through the process. Right now, Truphone's app works with the new eSIM feature and lets you add a secondary data plan to your phone.

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