eSIM on a Second-Hand iPhone: How It Works and Where It Goes Wrong

What an eSIM actually is

An eSIM is a SIM card that does not sit in a tray but in a chip inside the device. Your provider supplies a profile, usually as a QR code or through its app, and that profile is written to that chip. For the network nothing changes: you keep your number, you call and browse exactly as before. What does change is how your contract is attached to your device. A physical SIM card you take out and put into the next device. An eSIM has to be transferred, and that is one step more than most people expect. With a second-hand device it is usually there that things get awkward.

Does it work on the device you want to buy

Every iPhone from the generation of the XS and the XR onwards can work with an eSIM, alongside the ordinary SIM card. With the newer generations there is an extra detail: on devices made for the American market the SIM tray has been left out and only eSIM works. That device is not broken and not fake, but you are then entirely dependent on your provider offering eSIM and being able to supply a profile quickly. If you are buying second-hand and you still need a physical card, for example from a work contract or a prepaid card from abroad, check whether there is a SIM tray in it before you decide.

Where it goes wrong

• You erased your old device too early. If you restore an iPhone to factory settings, the eSIM profile disappears with it. So you always transfer before you erase, not afterwards.
• Your plan does not support it. With prepaid and with cheaper plans in particular, eSIM is not always available, or you have to go into a shop. Ask about it before you buy a device without a SIM tray.
• A new profile takes time. One provider sends it within a few minutes, another charges a fee or only does it during office hours. Replace your device on a Saturday evening and that can turn into a quiet Sunday.
• One profile, one device. You cannot use the same profile on two devices at once. As soon as it is on the new device, it stops on the old one.
• No connection, no eSIM. Installing a profile requires internet. If you are without wifi and without a working card, you will not get in. Do it at home, not on the train.
• Leftovers from the previous owner. A device that has not been completely erased can still contain an old profile. That no longer works, but it is in the way and it should not be there.

The right order

1. First make a backup of your old device, through iCloud or through a computer.
2. Put both devices next to each other, with bluetooth and wifi on, and make sure they both have enough battery.
3. Transfer the eSIM. With recent iOS versions that can be done straight from iPhone to iPhone, without your provider being involved. If that does not work, request a new profile and keep your customer number to hand.
4. Test three things on the new device: calling, receiving a text message and mobile data without wifi.
5. Only then erase the old device and sign it out of Find My.

That last step in that order is the whole story. Anyone who erases first and then transfers turns a quarter of an hour of work into a conversation with the helpdesk.

Two numbers on one device

An eSIM alongside your ordinary card means you can use two numbers on the same device. Handy for work and private life, or for a data package abroad alongside your regular number. Give the lines a clear name, set which line calls by default and which line your data uses, and check that per contact. Otherwise you send a private message from your work number or use up an expensive foreign package while you are sitting at home on the sofa. It pays to set that up calmly once instead of working it out afterwards from your bill.

If you sell your old device

Remove the eSIM deliberately if you sell a device on or trade it in. That is not because the next owner can do anything with it, but because your contract has no business being on a device that is no longer yours. More important still for the trade-in: sign out of iCloud and turn off Find My, and make sure there is no employer's management profile left on it. Devices with a SIM lock, an MDM lock or an active iCloud account we cannot buy, because they cannot be set up again. That is not a policy we are being strict about, it is simply a technical dead end.

What we do before the device reaches you

Every device goes through 32 checkpoints in the workshop in Zarren. Network lock, management profiles and the iCloud status are in that series, and the storage is completely overwritten, so there is no old profile left on it. The battery is measured and replaced below 85%, and you get 24 months of warranty on the device and the battery. If an eSIM still does not work after delivery, in practice that is almost always between you and your provider. If the device turns out not to suit your contract, you have 30 days to change your mind with free returns. Exactly which variant you are getting is stated with every device in the overview, and the rest of these kinds of questions are answered in the frequently asked questions.