Algorithm Selection for Classification problem
I don't think existing state-of-the-art technology will be adequate to solve this task effectively.  The current state of knowledge in NLP and AI probably isn't good enough to build something that will work well in practice.    Instead, I think you'll need to use humans.  Perhaps you can hire someone and train them -- that will probably be both cheaper and more effective than anything feasible with AI today.

(It seems impractical to obtain the large training sets typically needed for deep learning.  Also, your task requires deep understanding of spoken text at a semantic level, which is currently hard.  Finally, your task requires domain knowledge about the kinds of application tasks that clients are likely to ask about.)