To enhance call center security, companies can implement customer authentication using Twilio Flex plugins. Authentication involves proving identity with a factor that could be something known like a password or a physical attribute, such as a fingerprint. Options for authenticating users include sending one-time passcodes via SMS or email, callbacks, and voice recognition. To add customer authentication to Twilio Flex, developers need to set up a Verify service, deploy serverless functions using the Twilio CLI and serverless toolkit, and update their .env file with account credentials. Once deployed, agents can test the plugin by calling or messaging their Flex number, inputting an OTP provided by the customer, and verifying their identity. This authentication method helps prevent social engineering attacks by limiting caller information available to agents until they are properly authenticated.