Checks if a number looks somewhat like a E.164 number. Not an
        exhaustive check, as the API takes care of that

def validate_number(self, number):
        """ Checks if a number looks somewhat like a E.164 number. Not an
        exhaustive check, as the API takes care of that
        """
        if not isinstance(number, str):
            raise ElksException('Recipient phone number may not be empty')
        if number[0] == '+' and len(number) > 2 and len(number) < 16:
            return True
        else:
            raise ElksException("Phone number must be of format +CCCXXX...")