Two iPhones? In This Economy? Explaining iPhone Handoff

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Originally published at: Two iPhones? In This Economy? Explaining iPhone Handoff - TidBITS

I’m not a fancy person with a day iPhone and a night iPhone—and sadly, Apple does not send me new iPhones to review. But Apple seems to think I and some reasonable subset of its user base need iPhone Handoff, a new feature in iOS 27 that helps people with two iPhones to swap off using the same phone number by sharing an eSIM. Both iPhones have to share the same Messages, FaceTime, and Apple Account, so I find the use case a little baffling, as I’ll explain below.

eSIM is the virtual replacement for the increasingly tiny SIM (Subscriber Identification Module) cards that connect your phone, the network, and billing information. Some carriers already allow eSIM sharing across devices, so a phone, tablet, laptop, and smartwatch can use the same number, but that’s handled at the network level. This is the first time Apple has implemented eSIM sharing on the operating system side.

You might think that Apple already lets you share a phone number with Calls on Other Devices and Wi-Fi Calling. It’s true! But, in both cases, you’re drafting off your iPhone. Here’s how iPhone Handoff is distinct from those two features:

  • Using Calls on Other Devices (Settings > Apps > Phone > Calls on Other Devices) requires your iPhone to be within Bluetooth range of the iPad or Mac you’re calling from, since your device uses the iPhone to place the call. And it doesn’t work from one iPhone to another.
  • Wi-Fi Calling doesn’t require proximity between devices, because your device uses Wi-Fi to connect to your carrier’s network to place the phone call (Settings > Apps > Phone > Wi-Fi Calling). However, it only works when your device has access to a Wi-Fi network.
  • The new iPhone Handoff clones your eSIM to another iPhone. Both iPhones can place calls over a cellular network as if they were the same iPhone, although only one can be active at a time. No Wi-Fi is required, and the other iPhone doesn’t need to be nearby.

If you’re interested in iPhone Handoff, you may have to wait for your carrier to support it, or even switch carriers. Only T-Mobile in the US and Deutsche Telekom in Germany currently offer the service. T-Mobile charges $5 per month to use it. Deutsche Telekom offers iPhone Handoff as part of its MultiSIM service, which connects up to eight devices; some of its plans include MultiSIM at no extra charge, while others charge an extra €6.95 per month for MultiSIM.

To set up iPhone Handoff, both iPhones must have iOS 27 installed, share the same Apple Account login, and have Messages in iCloud activated to ensure Messages sync. You must also be signed into Messages and FaceTime with the same Apple Account, which is typical for most people, but might be a problem if you use each iPhone for a personal/work split. (Messages in iCloud has a very slight security risk if you don’t also enable Advanced Data Protection in iCloud. I cover this in greater depth in my book Take Control of Securing Your Apple Devices.)

Once you’ve enabled iPhone Handoff on your calling plan, you can use Settings > Cellular > iPhone Handoff on the iPhone with the eSIM installed to copy the eSIM over and turn the service on. Hold the two phones close together, and iOS prompts you to choose one as the “primary” and the other as the “secondary.” Apple describes slightly more complicated steps if you’re setting up a new iPhone from scratch, among other scenarios.

Picking which phone to make the primary involves some strategizing due to Apple’s limitations:

  • Some services, like Call Forwarding and Caller ID, may work only with the primary phone, Apple says.
  • You should pair your Apple Watch with the device you’ll use most, which may not be the iPhone it’s currently paired with. If the paired iPhone isn’t near your Apple Watch when you’re using the other iPhone, you may have some issues with syncing and data access.
  • Although you can add payment cards and car keys to Wallet on both devices, transit passes, IDs, and corporate badges may only work on one device at a time.

In use, iPhone Handoff relies on which iPhone you unlock. If you unlock the one that’s currently active, nothing happens. However, if you unlock the other iPhone, that activates iPhone Handoff, and it shows “Switched to this iPhone.” If you unlock both at the same time, I imagine bad things happen—will the entire cellular network crash, and will it be your fault? Apple doesn’t explain what would happen. I expect you’d get errors on both phones. The feature isn’t designed to let two iPhones make calls at the same time, but to let you use one number across two iPhones.

Calls, voicemail, and messages (SMS/MMS, RCS, and iMessage) all appear first on the active phone, which is also used as your current location for Find My. Presumably, when you switch to the secondary phone, all the communications that arrived on the primary one will sync over quickly, and vice versa.

So who is this feature for? I’ve had a hard time coming up with use cases beyond it being a godsend for iPhone reviewers, of course, who need to test new phones in real-world situations—that’s much easier when the test phone can be used for everything alongside the reviewer’s everyday phone. Perhaps this is in anticipation of people keeping an older, but useful iPhone when they buy an iPhone Duo? I can see that, given the Duo’s size and weight. I’ve sometimes had an older and newer iPhone, and I would have enjoyed this feature if I did more rugged activities (biking, kayaking, rock climbing, skydiving), where I’d prefer to put an older iPhone at risk.

Or there’s a weirdly underserved market of people who have personal and work phones, but want to use the same number on both, and have their Messages and FaceTime synced? But it’s hard to imagine it being useful for most of those people, who presumably want different phone numbers, message storage, and apps.

I have to assume Apple received enough requests for this feature, including from internal executives and staff, to feel it was worth developing. Or carriers found enough customers wanted to share a single number across multiple devices—like Deutsche Telekom’s more involved MultiSIM offering—that they convinced Apple to add iPhone Handoff. Is it something you’ll want to use in iOS 27?

For me, I have one iPhone, one iPad mini, one MacBook Pro, and one Mac Studio. I think I’m set!

For more about iPhone and Apple communications apps and options, Glenn Fleishman wrote an entire book, Take Control of FaceTime and Messages (which includes the Phone app). He is currently updating it for 27. If you buy the book now, you’ll get the upcoming edition for free.

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Yeah, I don’t know if a lot of people, at least in the US, are clamoring for this feature. I do see a fair number of people in my city carrying two phones, presumably due to work needs. But a couple of potential users popped into my head:

  • People who became adults when most couples did things like sharing one checking account, one credit card account, and, once Internet usage became common, one email account, one Amazon account, and one social media account. Now it is possible to have one mobile phone number that reaches two people.
  • If a parent wants to give a child a mobile phone that isn’t fully independent.

ETA: it’s gonna blow a lot of Gen Z and Gen Alpha minds when they have to tell the person answering a call who they want to talk to, ha ha!
https://www.nytimes.com/2026/09/05/style/gen-z-alpha-phone-greetings-etiquette.html

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I would have thought both of this, but…

…the number may only be used on iPhone at a time in this setup. You can’t have two phones active at the same time. When you unlock one, it switches to being active. You can sort of share a number using carrier services. This goes beyond that.

…iPhone Handoff requires synced Messages and FaceTime plus the one iPhone at a time limit.

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Thanks for the corrections! I’d say, then, that I can’t think of a huge market for Handoff but there must be a few things beyond my perspective that makes it attractive enough to be in iOS 27 and for mobile carriers to be able to charge a monthly fee.

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This completely confuses me. I am very interested in this feature as I am seriously considering getting a Duo (in addition to my main 18 Pro Max). I was originally thinking of just having the Duo be a wifi-only device, but when I heard of Handoff, I thought that would be better as there might be times I’d only take one phone and it would be helpful for it to have a cellular connection.

So what do you mean by active? I get that only one has a valid phone number and can ring for a call or use cellular data, but I had always pictured this as being a more deliberate switch between the two phones. Your article makes it sound like just unlocking and using the 2nd device switches the number to it. I had pictured myself using the Duo for video and games and books and other things that work better on a bigger screen, while still using my 18 as my main phone. I would only switch the cellular service over a specific times, such as when I want to only take one phone with me.

If it works the way you are suggesting – that I cannot watch a YT video on the Duo without it switching the phone number service to that device – that is a truly strange and dumb setup. I don’t think I’d want that at all. I’d be better off leaving the Duo as a wifi-only device and treating it like an iPad mini.

Isn’t there a way to have more manual control over when the number switches?

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Correct. This is explicitly stated in Apple’s documentation, linked from the article.

Also correct! Apple doesn’t say you can’t use both devices but unlocking switches the number and presence:

To move between your main iPhone and secondary iPhone, simply unlock the device that you want to start using — your phone number will automatically become active on that device.

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I read your summary specifically so I don’t have to read Apple’s technical material :wink:

(Actually, I didn’t even notice the link. I might check it out now that you’ve mentioned it.)

My specific use case for a Duo would be using it like an iPad, such as watching a video with it propped up nearby while I play with my phone. Sounds like that wouldn’t work with Handoff.

I had heard speculation that Apple introduced Handoff specifically so that skeptics with a single phone line could buy a Duo and have two devices, but the way it works negates that idea, at least in how I’d use the device.

Now I agree with your conclusion: this feature is for a very niche market!

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Why not? Use it like you’d use an iPad and an iPhone. Keep your phone as your cellular connection, but turn off cellular on your Duo and either use WiFi directly or, if there is no WiFi, turn on your phone’s hotspot and connect through it.

However, if you only travel with one device, then handoff is useful so that the active device will be the one in your pocket.

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I’ve always had a spare iPhone for the specific purpose of having a backup in case one of our iPhones is lost, stolen, or dies while it would be inconvenient to get a replacement - mostly for when we travel, but there are also times when it would be impossible to find time to get a replacement phone. I’ve never had it activated for cellular, and it’s only powered on to get iOS updates when those are released. It used to be that I kept my old phone as a spare when I upgraded, but last year I bought a 16e and gave my old 13 Pro to my son, whose old iPhone was in pretty rough shape.

Particularly when we travel, having a phone for us these days is pretty important. I do usually print itineraries, etc., as a backup, but almost everything is on iCloud (and the online service TripIt) and having a phone when moving around makes things so much easier.

So, depending on how much my carrier (Verizon) charges for this, I may very well use this feature, so that if something did happen to my old phone when I was traveling, I could quickly switch to the spare and be up and running with only minor inconveniences (for me this would be factory resetting my watch and pairing it with the spare phone.) And if something happened to my wife’s phone, or to one of my kids’ phones, I could turn off handoff, factory reset the spare, and let them activate the phone on their line until we were able to get a replacement.

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Also, like many things Apple does, they could be quietly laying the groundwork for something that’s coming in the future.

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For me. :grinning_face: I have a 10-year-old Toyota (see article in Tidbits some years ago). Its Bluetooth does work with my iPhone 11 Pro but not with my iPhone 16 Pro. The nice thing with this setup is that I have only apps that I use while driving on it organised in a way that makes it easy to launch them fast with minimal disturbance of my concentration.

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One person! I’ll add you to my count.

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Would this switch work if the active phone wasn’t available–lost, stolen, or stopped working? For me in Switzerland a functiioning cell phone is essential. It’s needed for online banking (no payments with checks here), logging into various websites, receiving important messages about appointments, etc. Because of this I have considered paying for the account of a second phone just in case.

Ned, old guy in switzerland

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I can think of a few of use cases.

  1. I am a journalist who goes into conflict zones. My phone is my life. I don’t want to take a phone loaded with all my personal info into the conflict zone. I do want my phone with Messages (I trust the is totally locked) and my ability to get photos and videos immediately to iCloud (which I also trust). I don’t want my Twitter (Cough X) account or my FB messenger on the conflict phone.

  2. I am member of the currently profitable class. The biggest growth area in the economy lately is selling to the rich. I want to have different phones for different occasions, just like my watches, or my cars.

  3. I am an elderly couple and we don’t want two phone numbers but we do want two iPhones. We are happy to have whoever has the phone handy to answer the way too infrequent calls from our children. We share our house, our checking, our credit cards, our email, and we want to share our phone number.

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No desktop or laptop computers? That’s where I do all of this work. I much prefer my 24" display, keyboard and mouse over any phone.

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Now I realize that my post shouldn’t have included just getting messages. However, the 2 banks that I have to deal with both have a “bank” app that needs their “access” app (sign in with a code or with face ID in order to log in). These apps are only available for the iPhone and the iPad, but not for the iMac. Also, paying bills here almost always requires scanning a QR code. This is done within the banking app, and I don’t think that it would work without it.

Ned

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I think the only issue would be if the person who stole the phone knew the passcode and unlocked the stolen phone. The number switches to the phone when it is unlocked, which requires biometrics or entering the passcode properly.

My question is if my primary device is stolen, so I switch to me secondary, is there a way to make the secondary phone the new primary, and to remove the lost/stolen primary phone from handoff without having the phone with you?

One thing I should note from my previous post is that we travel internationally at least once a year, and I don’t think it’s possible to activate a phone line on Verizon if you are away from its coverage area, so this would allow me to have two phones activated on my line already and use the secondary phone without getting a new eSIM in a foreign country if my primary phone is lost or stolen or broken.

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I understand your questioning of this “feature” but I do this now with Apple Watch.

I have an AW 8 that I use when I am working in the yard, fishing, etc.

I have an AW 10 I wear otherwise.

I can see people who do not have to trade in an older iPhone, and wondering what to do with the earlier model, using this feature.

I would…

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Not exactly. You use the Apple Watch as an extension of your existing iPhone, and an Apple Watch is typically personal to the same iPhone’s owner. This feature essentially syncs the two phones (calls, Messages, FaceTime), and requires only one be in use at a time, as unlocking switches the number.

I definitely see that if you kept an older iPhone as a backup, this could be useful. As I note, you might have an older iPhone you use for activities in which it’s more likely it could be damaged or you want a more compact iPhone, say. But it seems still niche!

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I have a new 17 Pro iPhone that I use only when I go into town. My formerly primary phone, a 13 mini, is now used as an extension phone to my 17. It (and my new non-cellular iPad Pro) answers phone calls, can send and receive messages, etc., About the only thing it is unable to do is initiate a phone call. But I can do that from my iPad Pro. Wi-Fi calling enabled on all those devices. My 13 mini leads a rough and tumble life, which is why I keep the 17 by the door and not in my pocket. I discovered the other day when I forgot to switch phones before going to town, that I could still use my mini to pay in stores as long as I was connected to their guest Wi-Fi for that minute or so at the register.

This works fine obviously at home on Wi-Fi. I can see where the handoff might be handy for other folks.