We're so sorry for the inconvenience here! This can happen in a few instances:
1)You may have an account associated with that phone number. If so, try signing in using your phone number.
You may be trying to use a VoIP number, which we currently don't support.
3)There may be a technical issue preventing us from verifying your phone number.
In each of those cases, please let us know the email address and phone number that you would like to sign up with. We'll be happy to pre-verify the phone number and email for you, and then send you a link to set up your password and remaining account details.