Missing “add mobile data plan”

Check with your carrier. Vodaphone has an activation sequence involving SMS messages sent to Vodaphone SMS addresses for instance, and once your coverage is activated with the carrier then (reportedly) features such as "Add data plan" can become available. Again, check with your carrier for details.

Failing that, reset your network settings.

Failing that, contact Apple Support.

Dual SIM iPhone models have been offered in three regions; China mainland, Hong Kong, and Macao.

If there are hardware issues, then warranty coverage may or may not be available outside of the country of purchase.

MaggieKong Said:

"Missing 'add mobile data plan': I couldn’t find the option 'add mobile data plan' to use eSIM. How can I activate this option? I’m using an iPhone 13 Pro with dual SIM card function."

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Troubleshooting iPhone Activation:

Getting Around this Error:

1. Go Here: If you can't Activate your iPhone - Apple Support
2. As it Reads: If your iPhone can't be activated or an alert says the activation server is unavailable or the SIM card is unsupported, learn what to do.

No Success?

Whom to Contact:

Contact your Carrier, as they are the one who provide you with the service of configuring a SIM card.

You have confirmed that your carrier is offering this additional eSIM option? Normally, the option to add a mobile plan will appear on the phone if the carrier supports that option.

I'm also not sure if the dual SIM iPhone supports eSIM as well. Have to do some checking on that.

You mention dual SIM iPhone 13 Pro. All iPhone 13 Pro models have dual-number capabilities, but only select iPhone 13 Pro models have dual SIM, and those models with dual SIM support do not have eSIM support. Is this a dual-SIM model?