code: def domestic_mobile_phone_number(value):
      
  
      try:
          parsed = phonenumbers.parse(value, 'GB')
      except NumberParseException:
          pass
      else:
          is_mobile = carrier._is_mobile(number_type(parsed))
          if is_mobile and phonenumbers.is_valid_number(parsed):
              return None
      raise ValidationError(MESSAGE_INVALID_PHONE_NUMBER)
docs: Confirms that the phone number is a valid UK phone number.
      @param {str} value
      @returns {None}
      @raises AssertionError