The error message "Unable to add cellular plan from this carrier" typically occurs when trying to install an eSIM on a network-locked device. You can follow these steps to check if the device is locked:
- Go to Settings > General, then tap on About.
- Under Carrier Lock, you should see "No SIM Restrictions." If you don't see this, please contact your carrier to unlock the device.
If your current provider confirms that your device is unlocked and you're still encountering issues, please contact support.
