I respectfully disagree with the initial routing point. I very strongly prefer a traditional tree to “I’m your voice assistant! In a few words, tell me how I can help!”.

The tree is structured and gives me an immediate sense of how to map my task to the support offering. If I’m calling, I probably have an issue that I can’t self-serve resolve via the customer portal or whatever, so walking the tree lets me get an idea of who can help.

The “voice assistant” gives me no sense of what the system is capable of or how to take advantage of those capabilities. So I’m left guessing at phrases or functions based off of the assumption that there’s still some kind of tree-like structure that’s been abstracted away. Same outcome, more cognitive overhead, plus I usually have to shout in my best William … Shatner … impression to get it to understand me.

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.

The other side is if you already know the tree you can automate dialing the right tones to get you to where you need if you call it often enough.