I fail to see how adding an LLM to an IVR could improve that situation. Keywords like “fill perscription”, “schedule technician”, and “do you have [blank] in stock” are already present and don’t need any kind of text generation to shunt a caller into the appropriate queue or run a query on a warehouse database.
Where, exactly, do you think an LLM could contribute other than, like, a computer generated bedtime story hotline or something?