During a voice call, the caller can press keys and capturing this user input and responding accordingly, you can make sophisticated IVR (Interactive Voice Response) systems.
You can set up an IVR menu with our API, with further explanation on how to do this in our Developers Documentation. Here we have written up a guide for building a basic IVR system.
If you are looking to set up IVR via our dashboard, you can do this with our Flow Builder. In this article you can read exactly how to set this up.