The expectation of customer support lines is that customers want to speak to humans. It isn't just the fact that these are semantics that aren't written anywhere and are open to change, because by using a human-like voice agent on a customer support line, you are pretending that that is a human, which is a scam or fraud.
If you really believe that the support can be good, then use a robotic text to speech, don't pretend it's a human. And make it clear to users that they are talking to a human, phone is a protocol that has the semantic that you speak to a human. Use something else.
The bottom line is that you have clients that registered under the belief that they could call a phone number and speak to a human, businesses are performing a short-term switcheroo at the expense of their clients, it's a scam.
> The expectation of customer support lines is that customers want to speak to humans.
Not really. The expectation is to be able to express their need in a natural language, maybe because their issue is not covered by a fixed-form web form (pun not intended).
So yeah AI might be a good fit in that scenario.
It's a protocol and network that has backwards compatibility with 19th century telegram wire networks that later were voice lines for a full century.
If that isn't the channel to speak to a human, nothing is. You can speak to a bot with an app or whatever.
At least make it sound robotty instead of pretending to be a human.