How to Set Up Wi-Fi Calling and an eSIM Backup Before the Next Outage

When a carrier has an outage, two settings can keep you reachable: Wi-Fi calling, which routes calls and texts over a Wi-Fi network, and a backup line on an eSIM, which is a second plan stored on your phone. Both need to be set up before you need them. This guide covers the steps for iPhone, Samsung Galaxy and Google Pixel, based on each maker’s support pages.

Key takeaways

• Wi-Fi calling needs a carrier that supports it and a Wi-Fi network. It also needs active service on your SIM or eSIM.
• Turn it on and confirm your emergency address while you still have service.
• An eSIM lets you add a second plan without a physical card, but whether you can use two carriers depends on your phone being unlocked.
• On iPhone, both lines can make and receive calls, but only one line can use cellular data at a time.
• The FCC warns that internet-based calling may not work if your internet connection fails or power goes out.

What is Wi-Fi calling, and will it work in an outage?

Wi-Fi calling sends your calls and texts over a Wi-Fi network instead of cell towers. Whether it helps during an outage depends on what failed. The phone makers say the feature requires an active line on your SIM or eSIM, so it will not help if your carrier’s account or core network is the problem. It can help when you have a Wi-Fi network but weak or no cell signal. Our report on the July 27 T-Mobile outage shows why it is worth having a plan before one hits.

How do you turn on Wi-Fi calling?

Not all carriers or devices support the feature, and the settings may differ by carrier. Samsung notes that on AT&T phones, VoLTE must be turned on before Wi-Fi calling will activate. Google advises checking with your carrier for fees and other details before you turn it on. On an iPhone, you can tell Wi-Fi calling is available when “Wi-Fi” appears in the status bar in Control Center.

How do you set your emergency address?

The FCC says providers must obtain your physical location and offer easy ways to update it, and it advises giving your accurate physical address and updating it promptly if you move. On Samsung, open Wi-Fi Calling and tap Emergency Address to update the address your carrier has on file. Apple says that when cellular service is available, your iPhone uses it for emergency calls, and that if cellular is not available, emergency calls might use Wi-Fi calling. Because location may not always be passed along automatically, state your location and call-back number to the dispatcher. The FCC’s guide covers interconnected VoIP services, so ask your carrier whether its Wi-Fi calling follows those rules.

What is an eSIM backup line, and how does it work?

An eSIM is a SIM built into your phone that you activate digitally. A backup line means holding a second plan, ideally from a different carrier, so one carrier’s outage does not take you fully offline. Apple says iPhone Dual SIM lets one phone run two active lines, usually a physical SIM plus an eSIM, and iPhone 13 models and later can also use two eSIMs. Both numbers can make and receive calls and send messages, but only one line can use cellular data at a time.

There is one condition for two carriers. Apple says your carrier must unlock your iPhone, or both plans must be from the same carrier. You can pick which line carries cellular data in Settings under Cellular, then Cellular Data. If you turn on Allow Cellular Data Switching, the iPhone can use data from both plans depending on coverage, but this does not work while data roaming is in use.

How do you add an eSIM?

• Carrier activation. If your carrier assigned an eSIM, follow the prompts or look for the notification “Carrier Cellular Plan Ready to Be Installed.”
• QR code. Scan the carrier’s QR code with the Camera app, or choose Use QR code during setup.
• Other methods. Some carriers send an activation link, offer an app, or let you enter details manually.
• Transfer. iPhone owners on iOS 18.4 or later can use eSIM Quick Transfer if their carrier supports it. On a Pixel, go to Network & internet, then SIMs, then Add SIM, then Transfer SIM from another device.

You need an eSIM-capable phone, such as an iPhone XS, XS Max, XR or later, and a carrier that supports eSIM. You also need a Wi-Fi network for activation in most cases. Google warns that once you convert a physical SIM to an eSIM on a Pixel, the physical SIM will no longer work, so keep the card until you confirm the eSIM works.

What else should you prepare?

• Test Wi-Fi calling now by placing a call with cellular turned off.
• Make sure your home Wi-Fi is strong where you spend time, using our tips to improve home Wi-Fi coverage.
• Be careful on shared networks, and read how to protect personal data on public Wi-Fi.
• Keep a charger or backup power handy, since the FCC notes internet-based calling may not work in a power outage.

FAQ

Does Wi-Fi calling work without a cell plan? No. Samsung says your phone must have active service through a SIM or eSIM.

Does Wi-Fi calling cost extra? Google advises checking with your carrier for fees and other details before you turn it on.

Can I use two carriers on one iPhone? Yes, if your carrier unlocked the iPhone or both plans are from the same carrier, per Apple.

Can both lines use data at once? On an iPhone, only one line can use cellular data at a time, though Allow Cellular Data Switching can use both plans depending on coverage.

For more, visit our Tech & Gadgets section.

Steps are from Apple’s Wi-Fi Calling page, Apple’s eSIM setup page, Apple’s Dual SIM page, Samsung Support, Pixel Phone Help and the FCC guide to VoIP and 911 service. Menus vary by phone, software version and carrier, so confirm with your carrier.