### Answer
Currently, there isn't specific information in the provided resources about customizing or adding a favicon directly through the Vapi platform. For such customization, typically, this would be handled within the HTML code of your own website or application where Vapi is integrated. You can set a favicon for your application that utilizes Vapi by adding a link to a favicon file in the head section of your HTML documents.
If this feature is crucial for your integration, considering your scenario with many open tabs, you might want to explore adding this through your application's frontend development rather than through Vapi directly.