PHONE number change

The correct steps depend on whether the number is used to sign in to the account or to receive security verification codes.

If the phone number is used to sign in

1. Open Manage how you sign in to Microsoft and sign in.
2. Under Account alias, select Add phone number.
3. Enter and verify the new number.
4. After the new number works, select Remove beside the old number.

If the old number is the primary alias, Microsoft may require another alias to be made primary before it can be removed. ^1^

If the number receives security codes

1. Sign in to your Microsoft account's Security page.
2. Select Manage how I sign in.
3. Select Add a new way to sign in or verify.
4. Add one of the methods offered and complete its verification.
5. Once the new method appears and works, remove the obsolete method if that option is available.

Microsoft is phasing out SMS for personal accounts, so adding another phone number might not be offered. If it is absent, use a recovery email address, Microsoft Authenticator, or a passkey instead. ^2^

If Microsoft says the new number is already in use

A phone number can be associated with only one Microsoft account. If Transfer appears, select it and follow the prompts. If it does not appear because the number was recently used with another account, select Change number and use another number, or try the transfer again after 30 days. ^3^

Do not remove the old number until the replacement sign-in or verification method has been successfully tested.

References

1. How do I change or remove my phone number in Skype? | Microsoft Support
2. Microsoft account security info & verification codes
3. Help with reusing phone numbers in a Microsoft account | Microsoft Support