Shouldn’t we be able to update or phones on data

It is possible to update over the data connection, if you are connected with 5G and have activated "Allow More Data over 5G", it is not possible to update over 4G / LTE.

If you do not have access to WiFi or 5G, then you can always update via iTunes on Windows, or in the Finder on Mac.

See more here:

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

Unless you have a new 5G connection and new iPhone, the update would take far too long over regular cellular and the download file often will likely not download correctly, messing everything up. Bottom line.....regular cellular is too slow.

Take the phone somewhere where you have a good WiFi connection.......like an Apple Store, or connect it using a cable to a Mac that has a good Internet connection.

channing224 wrote:

Why can’t we use data to update or phones I only have data do not have wifi

You can if you have an iphone 13 and carrier supports it.