Software update

If you have an iPhone 12, 13, or SE 3rd generation using 5G, you can update using cellular. Anything lower than that you will need to use WiFi or a computer connection.

Update your iPhone, iPad, or iPod touch

• If you have an iPhone 5S or 6/6plus, the highest you can update to is 12.5.6

• If you have an iPhone 6S through 13, you can update to 15.6.1

Go to Settings > General > Software Update.

Update your iPhone, iPad, or iPod touch using WiFi -

Update your iPhone, iPad, or iPod touch - Apple Support

Update using your computer -

Update iOS on iPhone - Apple Support

richey16 Said:

"Software update: how to get use mobile data to download and install new version"

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Updating an iPhone Through Cellular:

Updating your iPhone using Cellular may not an option for your model. This would be because model simply does not have the builtin hardware for this. See my User Tip: Use an iPhone 12 or later, that is using 5G, in order to update over Cellular - User Tip

Back Up First:

IMPORTANT: If you have an option to update, however, then be certain you backup your iPhone first. That way, you will have something to restore your iPhone from should anything go wrong with the update.

Open the Settings app on your iPhone.

1. Tap Cellular.
2. Tap Use Cellular Data for.
3. Turn on the switch next to App Store.