Scam or not? And where are "U.S. Tax Experts"?

As Maine comedian Bob Marley likes to say, “I’m not tryin’ to be a dink here, but…”
I’ve now gotten four robocalls direct to the voicemail on my cellphone from “U.S. Tax Experts.” The originating numbers have all been spoofed until today; that one goes to a recording that says something about “Thank you for calling, but no one is available to take your call. Please press 2 to opt out.” I pressed 0, and the call ended.
I finally got one of their “screening agents” to give me a web address: ntastax[dot]com, National Tax Advisory Services.
The “screening agents” all seem to have a slight accent, but I can’t place it. They also mention “Tax Group,” but I’ve got to get all the recordings on SpoofCard saved into a folder and then review them with my headphones on.
“George” (I’ll have to listen to the recording to get his last name) attempted to explain the robocalls by saying they have different “divisions” all over the country.
I’ve made two calls to National Tax Advisory Services, and nobody seems to know nuthin’ 'bout no robocalls. I did get to ask the young lady who answered my first call what the motivation would be for “U.S. Tax Experts” to redirect calls to NTAS, but she hung up on me. I also think I got robocalls last year that said they were from NTAS.
Whaddya think?
If anyone wants the callback numbers left in the voicemails, let me know.

I’ll call and bug em if you post the numbers

Sorry for the delay in replying. My main laptop had to go to the shop, and that machine has my (Excel) call logs.did manage to get some numbers from my SpoofCard logs.
See if you can get as far as I did on one call to (380) 233-0496. (That one lasted over 25½ minutes.) I’ve gotten some more info since I made this post, and the “referrals” do seem to lead to National Tax Advisory Services LLC. They are the defendants in at least two ongoing TCPA lawsuits that I’m aware of.
I collected (logged) four numbers, but accidentally deleted one of the voicemails. A friend of mine sent me a YouMail recording of a voicemail that he received, from yet another number in our area code, and with another callback number.
Here are my three other ones:
(607) 247-9389
(321) 398-0525
(773) 599-5051
I think these numbers are all–or at least mostly–Telnyx VoIPs. I’d like to see if I could report them to the carrier and get them nuked, but the “tax experts” would probably just get some new ones. (If they haven’t already replaced those above.)
If you call them, be prepared to hear a really bad instrumental version of Lynyrd Skynyrd’s “Simple Man” as the music-on-hold until the “screener” dude picks up.

It’s not a scam in the usual sense, but NTAS has been the defendant in a number of TCPA cases. Since I first posted this, I managed to get past their “pre-qualifying agents” and/or wheedle info out of same, and found out who they are.
There may be a class action suit brewing against NTAS and other spammers who use “ringless voicemails” to try and find customers. I’m not an attorney, but I can see three TCPA violations in every one of those calls, and I’ve logged five since October of 2022.