This number called my main number 8 times on Thursday 12/1 from 9:30 AM until 3:00 PM.
Also called my fax line and back office number 4 times each.

Never leave a message.

The office is closed for renovations during the winter.

Anybody else get calls from these people?

Yes, they call daily & of course never leave a message.  I don't answer & in fact blocked their number.  Have office phone forwarded to cell phone to make it easy to block

This number calls my office at least twice a day and never says anything then the call disconnects..

Recorded voice says "Important message, do not hang up" - I hung up!