Do You know any good IVR/VRU systems?

I’m looking for a new Vendor for our IVR/VRU. The system will need to be able to intergrate with an AS400 to retrieve information. Has anyone done this before? Do you know a vendor I can contact? I’ve pulled some info off the web but to be honest, I’m not comfortable with phone system intergration and I could use some expert advice.