To change your Outlook verification phone number, go to your Microsoft account security settings at account.microsoft.com/security or mysignins.microsoft.com/security-info, this is a Microsoft account setting, not something you do inside the Outlook app itself. Another documented route is account.live.com/names/manage, described as Manage how you sign in to Microsoft. The process involves removing the old number if you still have access to it, adding the new number, and verifying it with a code sent by SMS or call.
Sign in and verify your identity
Sign in to the Microsoft account you use with Outlook. If prompted, complete verification with an existing working method before you can change security info. This step ensures only the legitimate account holder can update the verification phone number.
Remove the old phone number
If the old number is still available, select Remove next to it under Security info before adding the new one. If the existing number is wrong, select Remove next to that number first, then add the correct one. This is a key part of changing your phone number on accounts, as it clears outdated contact details and prevents confusion between old and new numbers. If needed, remove the old number after the new one is verified.
Add and verify your new phone number
Select Add phone number or Add security info, choose Phone, enter the new mobile number, and complete the SMS or call verification code. Microsoft requires a mobile number for verification; a landline or VOIP number should be removed if listed.
Set the new number as default
After verification, choose Set as default or Make primary so the new number is used for future security codes. Return to Security info or the account alias page and confirm the new phone number is listed after verification. This step is similar to how you would change my trusted phone number on other services, you designate which number receives authentication requests.
What if you cannot access the old number?
Use the I don’t have any of these or Show more options link on the verification screen and follow the account recovery flow. This fallback path is documented by Microsoft for cases where you no longer have access to the old phone number or any alternate verification method.
Frequently Asked Questions
Is this done inside the Outlook app on iPhone or Android?
No. The documented change is made through Microsoft account security pages, not within the Outlook app itself. The same account pages work across all devices.
Can I use any phone number?
Microsoft guidance states a mobile number is required. If a landline or VOIP number is currently listed, it should be removed and replaced with a mobile number.
What if I need to change my number on T-Mobile or another carrier first?
If you are changing your mobile carrier number, you must complete that carrier-side process (such as how to change my number on T-Mobile) before updating your Microsoft account, since the verification code must arrive on the new number.
Does this process work for other accounts like PayPal?
No. This process is specific to Microsoft accounts. Each service has its own security settings, for example, to change my phone number on PayPal you would log into PayPal’s security settings, not Microsoft’s.
How long does it take for the new number to work?
Once you complete the verification code step, the new number is active immediately. You can test it by requesting a new verification code or signing in on a different device.
Are there limits on how many phone numbers I can add?
No exact limit on the number of phone numbers or changes was documented in the retrieved Microsoft pages.
