Why did my iMessage switch to my email?

Because iMessage needs the SIM that carries your phone number to be active in the phone. If you switch that line off while you travel, iMessage can fall back to your Apple ID email address.

Your Atli eSIM does not cause this. Atli is data-only: it carries no phone number, so it never registers one with iMessage either way.

What you actually see when it happens

• Your messages arrive from your email address instead of your number.
• Replies can start a new conversation instead of continuing the old one.
• Messages people send to your number may not reach you.

Check it in ten seconds, before you fly

You can test this at home, at any time.

1. 1Switch your own SIM line off.
2. 2Go to Settings › Apps › Messages › Send & Receive.
3. 3Look at the addresses listed there.

If your phone number is still listed, you are fine to travel with that line switched off. If it is not, your setup needs the line to stay on.

Switch your own line back on when you have finished testing.

The setup that keeps your number

Keep your own SIM switched on, and turn Data Roaming off on that line. Your number stays registered, and Atli carries the data.

Keep in mind that an active line can still be billed by your own carrier if you make or answer a call or send a text on it. See What can my own carrier charge me for?

For the full side-by-side settings on iPhone, Samsung and Pixel, see Can I use a travel eSIM with my own SIM?

If it has already switched

1. 1Turn your own SIM line back on.
2. 2Keep Data Roaming off on that line.
3. 3Open Settings › Apps › Messages › Send & Receive and check your number is listed again.

It can take a few minutes to re-register once the line is back on.