Why can’t I figure out how to confirm my number?

"Why can’t I figure out how to confirm my number?: how can I confirm my number?"

-------

What number? How are you using it to confirm what? Are you having an issue logging into your Apple Account?

Can't Add a Phone to your Apple Account?:

IF so, it seems you need to perm an update, and ensure that that the number isn't already associated with another account.

Updating to get the Latest Software:

Use a Computer and Ethernet:

Other than updating through the iPhone, itself, you can attempt an update through use of a computer. If you cannot use Wi-Fi, then use Ethernet.  See my User Tip: Update your iPhone Using a Computer - User Tip. On the computer, you would connect it through Ethernet, going directly into your router. For a Mac (or PC) that does not have Ethernet, this would be the adapter to use: Belkin USB-C to Gigabit Ethernet Adapter - Apple. If you get the same error, the model is likely just not compatible.

We need more information before we can help you. Please read this then repost your question: Writing an effective Apple Support Commun… - Apple Community