iMessage works with eSIM, but in many cases it requires additional configuration. The issue is that most eSIMs (especially travel eSIMs) do not support a phone number for SMS and calls, while iMessage tries to activate by using a phone number by default. The solution is to switch iMessage from using a phone number to using an email address (Apple ID).

Why is iMessage not working with eSIM?

The most common reasons are:

• the eSIM only supports mobile data (no SMS support for iMessage activation),
• the iPhone is trying to activate iMessage using a phone number instead of an email address,
• the physical SIM card has been disabled or has no signal,
• iMessage settings are not configured correctly.

Apple uses SMS messages to activate a phone number — if the eSIM does not support SMS, activation through the phone number will fail.

How to set up iMessage with an email instead of a phone number (iOS)

If iMessage is not working on your eSIM, follow these steps:

1. Go to:
   Settings → Messages
2. Turn on iMessage (if it is disabled)
3. Tap:
   Send & Receive
4. In the section:
   “You can receive iMessages to and reply from”
   select your email address (Apple ID) instead of your phone number
5. In the section:
   “Start New Conversations From”
   also select your email address

After making this change, iMessage will work over the internet (eSIM) without needing to use a phone number.

Can I use both my phone number and email address with iMessage?

Yes, but only if:

• your phone number is active and able to receive SMS messages (for example through a physical SIM card),
• iMessage has been successfully activated with that phone number.

If you are using a data-only eSIM, it is usually best to use only your email address with iMessage.

What should I do if iMessage still does not work?

If you are still experiencing issues after configuration:

• check your internet connection (Wi-Fi or eSIM),
• sign out of and back into your Apple ID:
  Settings → Messages → Send & Receive → Apple ID
• turn iMessage off and back on again (Settings → Messages) to refresh the service configuration,
• make sure your iPhone is running the latest version of iOS.