Twilio Functions can be used to add custom JavaScript code to Twilio Studio flows, allowing for more complex routing and decision-making. A Studio Run Function widget calls a Twilio Function, which compares the current time of day with business hours and returns a result, "open" or "after". The Split widget then routes the call based on this result. This combination gives Studio more power to route calls to various destinations. By integrating a Twilio Function into a Studio flow, users can create intelligent call forwards with logic-driven routing. Configuring a Twilio phone number to use the flow allows for testing and deployment of these complex flows.