"I'd like to schedule a smog check tomorrow or Wednesday?" rather than leaving a message and hoping for a callback that you don't miss either (and have go to voice mail).
Being able to have a voice appointment scheduling system (assuming that it isn't being jail broken https://www.youtube.com/shorts/GJVSDjRXVoo ) could be useful... though there are problems with giving it agency over decisions ( https://www.bbc.com/travel/article/20240222-air-canada-chatb... ).
If they were to have an app on their website, I wouldn't know because I don't use the webpage for that purpose - I call them.
Now, they've all got receptionists there that work full time and handle the appointments and take that first tier of service. These are larger places that have two receptionists working the full day (handling walkins, calling confirmations, and the other administrative tasks)... I don't think that an LLM (even with access to appointments) would do a better job than what they do (and certainly wouldn't be able to do the "ok, I showed up, now what do I do?")
However, I could see this for a small mechanic shop. When I lived in California, I went to what is now Shoreline Auto Care on El Camino and Shoreline - a small two bay mechanic... and that's not the type of place that has the business that can afford a full time receptionist.
So the question for a place like that... "what do you get for the phone calls you miss?"
Running a small website with a calendar booking link just sounds much easier, cheaper, less error prone, and a better UX than running a voice LLM that is connected to a RAG and calendar. And I still don't think the technology around us has been built to support small websites or small businesses.
If the LLM augmented voicemail is not much more than the business voicemail service that such places have now, is it enough value add?
That also implies other things - such as the capability to integrate with the calendar and appointment system which I'm still in the very hesitant side, but it could be an interesting service add on if it was properly limited.