In this tutorial, learn how to encrypt and redact data collected from Twilio Programmable Voice using <Gather> TwiML with Twilio Serverless Functions and Voice PCI Mode. The process involves creating a simple interactive voice application for caller authentication, encrypting sensitive information received from the caller, and enabling Voice PCI Mode to redact gathered information in Voice call logs. This tutorial helps protect sensitive data collected from <Gather> operations within Twilio's ecosystem and prevents anyone at Twilio from decrypting the values.