code: def voice_confirm_with(code)
        check_for_twilio_contactable_columns(:voice)
        if _TC_voice_confirmation_code.to_s.downcase == code.downcase
          # save the phone number into the 'confirmed phone number' attribute
          self._TC_voice_confirmed_phone_number = _TC_formatted_phone_number
          save
        else
          false
        end
      end
docs: Compares user-provided code with the stored confirmation
   code. If they match then the current phone number is set
   as confirmed by the user.