If you're calling it an "AI assistant" then it's probably not the type of system I was talking about and I probably don't like it either. AI call routing is having an IVR tree's functionality where the call system does the work to map it to a number in the tree. Anything more than that is getting into something else AI.

E.g. instead of waiting for the IVR tree to be read out to find out you needed to press 4 for the shipping department the AI asks "Please state the department you wish to connect to or reason for calling" and you just say "shipping" (or however much of a life story you want to give it) and it's the call system's job to figure out where in the menu that is instead. For repeat calls once you know its AI call routing you can just say "shipping" right as the call starts, the same as you'd known press "4" before the 2nd time around an IVR tree, except you don't have to remember the random digits.