Called at 12:01pm. NOT Diverted by a service I subscribe to that intercepts robo-dialed calls (rhymes with SoNoHobo). Callback from office phone -> "Your call is very important to us. Please stay on the line and you will be transferred to the next available agent."
This is the same spiel I got when calling back two other ring-throughs that were nonetheless robo-dialed. This spiel also alternated with another boilerplate fake greeting, a fake but reasonable-sounding message about office hours (fake because it gives you office hours even during "office hours"). This fake office hours is one I've gotten from at least 5 different one-time-used (so far) "Unavailable" callers.
My interpretation of this new pattern is some especially persistent pest who is using many new numbers to try to get around that service that I could name here, but you would never see the post if I did.
I reported today's pest number to that service; I do not waste time blocking because they seem to try a new number every time, with no repeat usage yet.
Given the experience I've had over the four years since, out of curiosity, I began keeping a record of these "spam" calls, I would guess that this is a pest who offers credit card payment "relief" or shills for donations regarding breast cancer, which they keep 95% of.
A couple of times, to stop the rings (which strangely do not go to voice mail), I've hit "Talk" then "Off," so one thing I have not figured out yet is why, since they get a pickup, however briefly, why I haven't gotten a second call from those numbers. I mean, if they really are trying to run some scam or plead for a phony charity, you'd think they'd call back when they got a "live" one.
Ah, well. They'll keep changing numbers, and I'll keep reporting them to that service I can not name here.