I think most folks already wouldn't be able to tell, with the modern TTS.
It's like AI photos, they fool you unless you're looking for it.
So, I agree. But I believe the problem is pretty solvable with enough tokens.
This is the critical data —» how many people hang up on the AI chatbot vs how many people hang up on the voice message prompt.
If it is even close, well, the AI needs to be improved.
If the AI is way ahead, but still loses/drops more than a live receptionist (outsourced or in-house), the AI either needs improvement, or to be dumped for a live receptionist, and that's kind of a spreadsheet problem (how many jobs lost in each case, vs costs).
But the real question you should also ask is what else can that human do for you that the AI can't because they have eyes and ears and hands?
If we take OP’s post at face value, presumably his brother is already at 100% capacity otherwise he wouldn’t be missing all these calls.
I don’t know if he’s “tested”, but he said he’s happy enough with the service. We don’t always have to AB test every possible option - sometimes good enough is good enough.
The model is exactly like Planet Fitness or similar gyms: It doesn't work if everyone visits at once, but you plan on most people using it once a week.
That said, a good service writer is worth their weight in gold. Also, they are typically going to be the person you end up selling the business to when you retire. Most mechanics aren't good enough at the business side of things to actually buy, but service writers are.
“Hey can you look out and see if Joe’s almost done with the blue Chrysler?” is an easy ask for the phone answerer at my local Joe’s shop (it’s his wife, and as a bonus she’ll also holler at him or his crew to hurry up because @alwa is waiting on it).
Contrast with the grant-funded pharmacy I use. Some management type suggested they could deal with their insane level of overwork by automating away the phones to a hostile and labyrinthine network of IVRs. Oh, it has “AI,” but only to force choices between forks in decisions trees corresponding to questions I didn’t have—and every path still eventually ends in “this voice mailbox is full, goodbye.”
After literal hours of my life trying to wrestle their IVRs into helping—I do sympathize with their workload and don’t want to be a special snowflake—I now drive 30 minutes to ask questions face to face.
In general I’ve maxed out what’s discoverable by automated means before I call. So a call center is both useless and insulting.
Partly as a preventative measure: we trust them. In the rare cases when they find something, it’s real. As a consequence we get ahead of brewing problems.
Plus loyalty, to some extent; we try to throw work their way when we can, even if we probably could handle it ourselves. The relationship between our families goes back a good 60 years by now.
Fully grant that my situation is unlikely to be representative. And no shade toward OP—it sounds like a cool project thoughtfully done, and a real improvement over the status quo for her relative!
Obviously that process could happen purely via voice but I think there's not as much love for walking through forms in a phone call.
If Joe has a PC in the shop with a tailored UI, he could get pings of pending requests and when he comes up for air, update the intake (via voice to minimize greasy hands) and initiate a call back then and there?
Christ just hire some local teenager or whomever. There's people who will work for minimum wage.
More to the point - does this garage even have the time and space to service more vehicles? Generating a bunch of new low-value/low-loyalty customers takes up time and space and might have a lower return-per-hour while making it harder to retain higher value returning customers.
Additionally, as "luxury mechanic" (apparently specializing in BMW but servicing other makes) you'll need to appeal to "luxury drivers" and bolting on more crap that makes the experience worse is probably not the way to do that.