Help with reusing phone numbers in a Microsoft account

If you received the message "This phone number has already been taken" when adding a phone number to an account, it means the phone number is already associated with another Microsoft account.

You can transfer the phone number if you own both accounts.

1. Sign in to the account that has the phone number you want to move.

2. Select Remove next to the phone number to be transferred.

   Note: You can only remove the phone number if you have another username on the account. We recommend having at least two additional forms of contact on your account.

3. Sign out.

4. Sign in to the account that you want to add the phone number to.

5. Select Add phone number to add the number to the account.

If you see the message "[phone number] is already a Microsoft account" when trying to create a new Microsoft account, it means that the phone number you entered is already associated with another Microsoft account. 

• If your phone number is associated with a different Microsoft account, and you want to associate it with your new Microsoft account, select Sign up from the message and follow the prompts to remove it from the existing account and move it to the new account.

• If the phone number is associated with another Microsoft account you own, you can use your phone number to sign in since it’s already a Microsoft account. Select Sign in from the message and follow the prompts.

If you see the message "We noticed [phone number] is already used to sign in to [another number]" when trying to add the number as an alias or as another username, it means that the phone number you entered is already associated with another Microsoft account. 

• If your phone number is already an alias for another Microsoft account you own, you can use your phone number to sign in since it’s already a Microsoft account.
  
  ​​​​​​​Select Continue to sign in without adding another phone number.

  Note: Some Microsoft products and services require a phone number, so you should choose a different number to associate with your account if possible.

• If your phone number is an alias for a different account and you want to associate it with your Microsoft account, select Transfer number and follow the prompts.

• If you don't see the transfer option, it's because the phone number has been recently used in another Microsoft account. Select Change number to choose a different number to associate with your account. If the phone number is new to you, try again after 30 days to see the Transfer option.

To protect your data, a phone number can only be added to a single Microsoft account.

So, after signing into a Microsoft app and you see a message asking if you want to Change number, it means this number is already associated with a different account and you'll need to make a choice about how to continue.

You might see this if:

• You created a Microsoft account with that number in the past, but you forgot about it

• One of your family members is already using this phone number with their own account

• This is a new phone number for you. Since mobile carriers can reuse phone numbers after 30-days, it's possible the previous owner of that phone number had already associated it with their own Microsoft account.

Since the number was only recently added to the other account, your only option is to use a different mobile number.

Your option

To fix this, you can add a different mobile number by selecting Change number.

Use the Change option if you want to add a different phone number to be used with this app, so you can access all the features of the app.

If you select Change number, you'll be brought back to the phone number entry screen where you can select a different mobile number to use with this app.