A/B testing with Twilio and Eppo is a method used to determine which version of an SMS message performs better in terms of user response rates. The process involves setting up an A/B test, which randomly assigns users to one of two versions of the SMS message, and then analyzing the results to see which version performs better. In this tutorial, we use Eppo as the end-to-end experimentation platform, Twilio Studio as a drag-and-drop tool for building voice and messaging applications, and Segment as a Customer Data Platform tool that can collect data and send it to a data warehouse like BigQuery. The workflow involves connecting BigQuery to Eppo, setting up Segment, creating a Feature Flag in Eppo, deploying Twilio Functions, publishing Studio Flow, creating an Experiment in Eppo, and analyzing the results to see which version of the SMS message performs better.