Check the combination
The phone model, regional variant, plan and provider all matter. A handset advertising eSIM does not prove that an account is eligible for every installation method. Tablet and wearable products can have different restrictions from phone products.
Before changing anything, make sure account recovery is available without relying exclusively on the phone being replaced. Save instructions and have suitable internet access ready.
Install without losing the working route
Follow the official provider process. Keep the old device until the new one receives ordinary calls and texts and can use mobile data. Apps connected over Wi-Fi do not prove that the cellular line works.
If an error appears, record its wording. Do not repeatedly delete a profile whose replacement procedure you do not understand. Some activation credentials may not be reusable.
Manage two lines
Label each line and set voice and data defaults. Review automatic data fallback before a trip, because it can select a line with different overseas conditions.
The number, SIM profile and app credentials are separate pieces of the setup. Transferring one does not guarantee the others have moved. Deleting a profile does not end an agreement.