Asterisk: The Definitive Guide, 4th Edition

Chapter 17. Interactive Voice Response

One day Alice came to a fork in the road and saw a Cheshire cat in a tree. “Which road do I take?” she asked.

“Where do you want to go?” was his response.

“I don’t know,” Alice answered.

“Then,” said the cat, “it doesn’t matter.”

—Lewis Carroll

In this chapter, we will talk about IVR. If what you want is an automated attendant, we have written a chapter for that as well (Chapter 15). The term IVR is often misused to refer to an automated attendant, but the two are very different things.^[177]

What Is IVR?

The purpose of an Interactive Voice Response (IVR) system is to take input from a caller, perform an action based on that input (commonly, looking up data in an external system such as a database), and return a result to the caller.^[178] Traditionally, IVR systems have been complex, expensive, and annoying to implement. Asterisk changes all that.

Caution

Asterisk blurs the lines between traditional PBXs and IVR systems. The power and flexibility of the Asterisk dialplan results in a system where nearly every extension could be considered an IVR in the traditional sense of the term.

Components of an IVR

The most basic elements of an IVR are quite similar to those of an automated attendant, though the goal is different. We need at least one prompt to tell the caller what the IVR expects from him, a method of receiving input from the caller, logic to verify that the caller’s response is valid input, logic to determine what the next step of the IVR should ...