Building an agent chat utility that connects customer service departments to mobile customers via SMS on Toll-free numbers using Twilio's powerful Messaging API. The application will have functions such as displaying incoming and outgoing text messages, internal agent communication, and collaboration. The tutorial uses XAMPP, ngrok, and PHP to build the basic chat functionality, which is then enhanced with Twilio's toll-free SMS feature. The system displays incoming text messages in a chat window, allows agents to reply using the @ symbol followed by the phone number and message text, and integrates with Twilio's Messages resource to send outgoing messages. The tutorial provides a step-by-step guide on how to set up the system, including configuring a Toll-free number, handling incoming texts from customers, and sending text messages back to customers.