When I try to set up an instant sandbox for Microsoft 365 as part of Microsoft 365 Dev Program (https://developer.microsoft.com/en-us/microsoft-365/profile), I am getting 40901 error message

Question

When I try to register my phone I get a message saying it is already registered to existing developer account.

We can't continue with the signup process for the following reason:

• Your phone number is already associated with an existing developer account.

For help with your Microsoft account, go to Microsoft account and verify your information.

MS-CorrelationId: 00000000-ce08-43ca-865b-f7afa261937e

Code: 40901