Exact same thing happened while I was on a new business call. It screwed up the call so much that both parties had to hang up.  Frustrating spammers!

They just called me. I didn't answer.

After getting FIVE phone calls from this number today, I bit the bullet and called them back, just long enough to get the start of the message,  It's an outfit calling itself "Rushmore Research" and as far as I can tell, it must be a phony name as it appears nowhere on the internet that I can find...other than a "sales center" here in Houston ... hmmmmm I'd say SCAM!!! And of course, they can call as our congress critters in their infinite wisdom, exempted survey, political and research calls from the DNC list.

"Unassigned" called me 4 times in less than 24 hours. I never answered and they never left a message. I never WILL answer, either! (Nor do I answer from "Unnamed", "Unknown name", "Toll free caller", etc......