Managing personal Outlook.com account settings, security, and privacy
For personal Microsoft accounts, Microsoft now says you can no longer add a phone number as a new security method. This method is being phased out. See official document here.
Are you hoping to update the contact method to receive the 2FA verification?
You will need to use email, the authentication app, or passkey.
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Also for your Teams meeting/interview, you can launch the meeting link in a web browser, when prompted to use the app, you can choose not to use the app. When prompted to sign in, you can choose not to sign in. You will be offered to enter your display name and enter the meeting without a Microsoft account. I know you didn't ask this, but just want to share this in case you run into any account issue.