iPhone XS Dual-SIM Could Be a Game-Changer -- But There's a Catch

Apple’s new iPhones could be a game-changer for international travel.

The company introduced at its iPhone announcement on Wednesday that new iPhone XR, XS and XS Max models will have support for dual-SIM cards that can offer travelers the same rates as local users.

While the three new iPhones could serve as a saving grace for many travelers, there’s a caveat for support that means it’s not quite as straightforward as jumping on a plane and hoping for the best.

What is DSDS?

Phil Schiller, Apple’s Senior Vice President of Worldwide Marketing and mainstay of the annual September events, revealed Apple’s DSDS — which stands for “Dual SIM Dual Standby” — technology, which is enabled in the US by eSIM (“embedded SIM”) technology.

What is eSIM?

eSIM is a relatively new standard that previously appeared in the Apple Watch Series 3 cellular models, users can add a new eSIM card by visiting the Settings app and scanning a QR code. The phone can store more than one eSIM, but you can only use one at a time. When the second SIM is activated, iOS will ask users to choose a default line for things like iMessage and calling people from outside of the address book. While both numbers can make and receive calls, the user must visit the “Settings” app to move between different data connections.

The eSIM feature means users can avoid ballooning phone bills from carriers as a result of international data plans. Verizon charges up to $2.99 per minute for international roaming voice calls. Similarly, AT&T charges up to $3 per minute for calls from outside of North America or Europe.

Apple’s support means users can arrive straight out of an airport, pop in a local SIM card, and pay the same rates as people living locally. Users can keep texting with Facebook Messenger, find their reservations in emails, and navigate through rainy streets with GPS.

Some secondary cards can enable cheap prices in multiple countries. European Union-based carriers cannot charge for roaming throughout the 28 member states, assuming you’re just visiting the roaming state. Three has extended this even further for British customers, offering no-extra-cost roaming in 71 countries worldwide including the United States, Brazil, Vietnam and Israel.

Unfortunately, it’s not quite that straightforward. The functionality won’t be active at launch, requiring an iOS 12 software update coming later this year. You also can’t use two CDMA SIMs at the same time.

Most importantly, Apple lists only 16 wireless carriers in 10 countries that support its eSIM implementation. Three of the carriers are in the United States, with AT&T, Verizon and T-Mobile supporting the new format. This makes international travel rather difficult, as you’ll need to ensure at least one carrier is eSIM-friendly. Two global carriers support the feature, GigSky and Truphone, but for the most part consumers on the street will have to proceed with caution while border hopping.

The China iPhone Will Have Two Literal SIM Cards

The iPhone XS Max sold in China, Hong Kong and Macau offers dual SIM with two physical nano SIM cards, facing back-to-back on the SIM tray, meaning select users won’t have to play the eSIM support game. For the rest of the world, international travel will depend on crossing your fingers and hoping that your carrier supports the new standard.

The shift could encourage more carriers to adopt the standard, and that would be great news for Apple. Neil Shah, research director at Counterpoint Research, noted that Apple will maintain control over which carriers will work with its implementation, giving it control over carrier partnerships. The support may seem like an oversight, but it could be a clever way for the iPhone maker to leverage more control over its offerings.

See also: How to Pre-Order the iPhone XS and iPhone Xr (AKA the iPhone 9)