Twilio has implemented measures to prevent certain numbers from being dialed with Twilio-powered applications, such as 911, 411, and premium paid lines, to protect users and prevent unwanted calls. This feature returns a specific error code when these numbers are attempted to be dialed, allowing developers to rest assured that their applications will not compromise legitimate emergencies or toll lines. By using this feature, developers can ensure the security of their applications and provide a better user experience.