I'm the latest victim...this started last night, received 8 calls but they left no VM. Now this morning, they called 4 times in a row and again, no VM. Im just NOT going to answer. They'll stop sooner or later.
I did however sign up for some dumb Grant crap a few days ago while searching for stimulus check info. From reading most of these posts, it seems like that is the source to these annoying calls. Here's their link for anyone who wants to make a complaint as I'm about to.
http://new.freegrantsearch.com/stimulus-payments/This is the number listed on that site (202)330-5638 help@FreeGrantSearch.com