After a live voice, it serves them better than leaving messages. Unless it's perhaps a threat from the bogus IRS, leaving messages does little for most scammers. If you're able, turn off your answering machine and let the phone ring clear through. It's possible to outlast them.

Same thing.  Phone sez Flushing MI.  Toilet brain.

said something like Great Lakes Lawn Service.
DNC violator

Told me it was about some visa card. Voice sounds annimated.