code: public function send($notifiable, Notification $notification)
      {
          $to = $this->getTo($notifiable);
  
          $message = $notification->toSmsGateway($notifiable);
  
          if (is_string($message)) {
              $message = new SmsGatewayMessage($message);
          }
  
          return $this->client->send($this->buildParams($message, $to));
      }
docs: Send the given notification.
  
  @param mixed        $notifiable
  @param Notification $notification
  
  @return array|void