We're so sorry for the inconvenience here! This can happen in a few instances:
1. You may already have an account associated with that phone number.
2. 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 these cases, please reach out to us and provide the email address and phone number that you would like to sign up with, and we'll happily help you to set up your account!