I've worked on some, but they were never ready for prime-time, so they were never converted to products, only custom developments.
You want to be looking for something that uses CTI (Computer Telephony Integration) boards, like Dialogic, Natural Microsystems or Music Telecom.
The ones that we wrote would actually test the IVR tree by using the Speach API (SAPI) and check for keywords in the phrases. But that was many years ago. Maybe someone has built a production version, but I haven't seen it.
pansophic