iMessage is an Apple IOS based service for instant messaging. The service is typically bound to a phone number and more often than not this is the one that belongs to the primary SIM in the device.
With an eSIM installed and being used for data services, it is still possible to use the iMessage service when the following considerations are made;
- the line which the SIM with the phone number attached to iMessage requires to remain turned on
- data roaming should be turned off on the primary SIM to ensure the eSIM is used for data services
- careful note should be made that as long as phone calls are not made or answered and SMS are not sent then no carrier roaming charges will be incurred
It is then still possible to receive messages through iMessage for the phone number.
An alternative would be to bind an email address to iMessage. Since email operates over data services iMessage would continue to operate through the eSIM and its data services.
Our install guides for your device will bring you to the above configuration. If you are concerned about voice and SMS roaming charges, you should always check with your carrier before travelling to seek further advice.