Mobile number

Go here live.xbox.com/.../billingaccountinformation :-)

Hello,

You should be able to change the billing telephone number by visiting this page here. If you're unable to and you entered the wrong phone number, you should be able to change it by following the directions below. There will be a wait time in resetting the security information so any sort of account changes you wish to change like automatic renewal etc will need to be done over the phone via XBOX Support.

I can’t access any of my proofs

If all of your security proofs (phone numbers, emails, trusted PCs) are outdated or wrong, you can request to have all the proofs removed from your account and enter new proofs. Follow these steps to reset all the security proofs for your Microsoft account:

Go to Remove all security info and sign in with your Microsoft account.
Click Remove all.
Enter new, valid proofs. These proofs will automatically be added to your account once the old proofs are removed.

How long will it take to reset my security proofs? Is there a way to expedite this process?

When you opt to have all your security info removed, messages are sent to every phone and email proof on your account. This process can take anywhere from 30 days to 6 months, depending on the number of proofs on your account. This is for your protection.

The process of resetting your security proofs is designed to make sure that your account isn't being accessed by an unauthorized user and to safeguard your account information (including any credit card information associated with your account).

Xbox Support cannot expedite this process.

You have the option of creating a new account at any time. However, once your existing account is recovered, the two accounts cannot be merged (for instance, any achievements earned or gamerscore points accumulated through your new account cannot be added to your old account).