Using both sim on mobile data

demetris2606,

Thanks for getting back to us. We'd recommend contacting your eSIM provider to find out exactly what your data options are when in another country.

Also see: About cellular data roaming options for your iPhone and iPad.

Cheers,

Hi demetris2606,

Thanks for coming to Apple Support Communities for help today with using eSIM data only.

Please see: Using Dual SIM with an eSIM and specifically the section:

"Change your cellular data number

One number at a time can use cellular data. To change which number uses cellular data, follow these steps: 

1. Go to Settings.
2. Tap either Cellular or Mobile Data.
3. Tap Cellular Data. 
4. Tap the number you want to use cellular data. 

If you turn on Allow Cellular Data Switching, then while you're on a voice call on your voice-only number, that number automatically switches to use voice and data. This lets you use both voice and data while on the call.

If you turn off Allow Cellular Data Switching and you're active on a voice number that isn't your designated cellular-data number, then cellular data won't work while you're on the call.

To turn on Allow Cellular Data Switching, follow these steps:

1. Go to Settings.
2. Tap either Cellular or Mobile Data.
3. Tap Cellular Data.
4. Turn on Allow Cellular Data Switching."

Have a fantastic day!