Sending, receiving, and organizing email in Outlook.com
Hello,
For Security reasons, Microsoft is phasing out SMS verification methods for personal accounts. This means you will no longer be able to use your phone number to verify your identity or recover your account.
Reference:
Microsoft to stop sending SMS codes for personal accounts
This may be why you’re not receiving the verification code on your primary mobile number. Microsoft recommends having at least three verification methods on your account. That way, if one method becomes outdated or stops working, you can use another to sign in.
However, if your phone number is your only verification method and you’ve forgotten your account password, you may need to replace your security information.
On the Verify Your Identity screen, select 'I don't have any of these' and follow the prompts to replace the Security Information.
Note:
If you remove all of your previous security information and replace it with something new, your account will be put into a restricted state for 30 days.
Once your security information has been updated, you can reset your account password.
However, you’ll remain signed in to the Microsoft apps and services you’re already using. You’ll only be unable to access services that require you to verify your security information.