this number calls us at least twice everyday for several months. I also do not answer calls that I don't know the number but finally decided to call the number back. Though caller ID says IMC, when I called back it was the NRA & i requested to have our number removed from the list. Said it would take a couple of days to be changed so we'll see.
I have received numerous calls from this number. I do not answer calls from numbers I do not recognize, assuming that if the call is important, the caller will leave a message. These people never do.