This feature helps you when you are not able to answer the phone but want to leave the caller a message. This is similar to the iPhone feature when you have to decline a call and send them a message simultaneously.
You simply have to activate 'canned responses' in your number settings on manage.yodel.io and define your messages. There are no limitations so just try it out!
Here are some examples to show you what you can do with the canned responses: