Yes, when using Openline abroad. This iPhone feature auto-fails-over to your other line during weak signal. If your other line is your home carrier, that means surprise international roaming charges.

Settings → Cellular → Cellular Data → Allow Cellular Data Switching → OFF.

Turn it back on when you're home and using both lines domestically.

Still stuck?

Reach Openline support 24/7 through any of these channels:

When you write in, include your purchase code (the OL-… code we emailed you) and, if the eSIM is already installed, its ICCID (Settings → Cellular → tap the Openline line). That's enough for us to find your plan and diagnose without back-and-forth.