Swapping eSIM between two iPhones

I recently swapped two iPhones. The idea is, we had two iPhones, logged into two iCloud accounts, using two lines on the same cellular plan, and we wanted to swap the physical devices. After swapping, we needed the phones to work correctly with the other phone number, but we also hoped we would have the same settings, all our photos and apps, and have everything just work.

In the old world where we had physical SIM cards, this is very easy. You basically just swap the SIM cards — pop them out, pop them in the other phone. (Of course, you basically need to “log out” of the phone and log into the other phone, too, but the whole idea really is just that simple.)

With eSIM, I wasn’t confident—I worried that erasing and setting up the phones would somehow lose an eSIM.

Eventually, I accepted that there were no articles on the internet that would reassure me, I just went for it, and we got it working!

This was our process:

1. Backup both phones.
   Apple article about backing up your device. If you have an Apple Watch, maybe read step 4 before you do anything more.
2. Erase phone #1. Including the eSIM.
   Apple article about erasing a phone.
3. Transfer phone #2 to phone #1.
   Follow the instructions to set up phone #1 as if you had just turned on a new iPhone for the first time, and choose the options for transferring from another iPhone. It’s a very easy process, lots of pictures and clear instructions.
4. Maybe: pair your Apple Watch with new phone.
   This honestly could be the hardest part. We only had 1 Apple Watch in the mix, hopefully you don’t have a Watch on each phone. With one Apple Watch, make sure phone #2 in these instructions is the one with the Apple Watch. This Apple knowledgebase article tells how to pair with a new phone, and has sections at the bottom for special cases, like if you don’t have your old iPhone (for instance, if you accidentally do step 5 below before you do step 4, like I did). I had another blunder, too. I accidentally hit the button for “Erase All” instead of erasing and keeping the cellular plan. Fortunately, when setting up the Watch as new after erasing it, I could set up from a backup and that prompted me whether I wanted to reactivate the same T-Mobile cellular plan, and it was as easy as selecting “yes.”
5. Erase phone #2.
   Apple article link again.
6. Restore phone #2 from the backup of phone #1.
   Follow instructions to set up an iPhone and restore from an iCloud backup.
7. Set up cellular on phone #2 buy calling T-Mobile.
   I was dreading calling, but this turned out to be a really painless call. I couldn’t find a way to do it without calling T-Mobile.

Hope you found this article interesting or useful!