This tutorial provides a comprehensive guide on creating a simple notification system using Twilio CLI, Programmable Voice, and Programmable Messaging. The author outlines the prerequisites for setting up the project, including obtaining a Twilio account, installing Twilio CLI, and configuring the login credentials. The tutorial then covers how to list available phone numbers, purchase an incoming phone number, and test the Twilio CLI by sending a simple message to a mobile device. Next, it explains how to create a CSV file containing the information for recipients, including name, date, hours start, and hours stop. The author provides a bash script that parses the CSV file and contacts the recipients accordingly, using either SMS or voice messages depending on the channel specified in the CSV file. Finally, the tutorial offers suggestions for improving the script, such as adding email as a channel option and sending notifications using Twilio APIs instead.