There might be 2 reasons on why this is happening: 
- The phone number that you are uploading is already in use or onboarded to GoCorp 
- The email address that you are uploading is already in use or onboarded to GoCorp 

To understand which one is the issue, please refer to the error message that will show one of the followings: 
- Phone number is already in use 
- Email address is already in use