public function sendShortMessage($receivers, $body = null)
    {
        if (! $receivers instanceof ShortMessage) {
            $receivers = $this->factory->create($receivers, $body);
        }

        if (is_callable($this->beforeSingleShortMessageCallback)) {
            call_user_func_array($this->beforeSingleShortMessageCallback, [$receivers]);
        }

        $response = $this->client->sendShortMessage($receivers);

        if (is_callable($this->afterSingleShortMessageCallback)) {
            call_user_func_array($this->afterSingleShortMessageCallback, [$response, $receivers]);
        }

        return $response;
    }