Hi @seadude , thank you for reaching us.
ACS already supports receiving messages through Event Grid. In summary you need to register to the SMS Received event, and you should receive Event Grid events each time purchased number receive a message.
For more information you can check SMS FAQ here sms-faq and our QuickStart sample here handle-sms-events
When you set up the Event Grid you can configure it to forward the notification to a Web Hook for example and in this way, you can notify your application about the incoming message.