The Vonage SMS API allows developers to send and receive messages around the world using a virtual number rented from Vonage. This tutorial uses Node.js, Express, Ably, and Angular to demonstrate how to receive an SMS, send it via Ably to a web browser, and display it as a notification in a Single Page Application. The process involves creating a Webhook endpoint with Express, registering it with Vonage, sending the message via Ably, and displaying the notification in an Angular application.