Called and hung up when I answered.

Caller ID said IMC - did not answer and they left no message

Called nine times since Aug 29th and never leaves a message.

Calling relentlessly, never leaving a message.  Blocked after weeks of calls at all hours of the day.  After researching and finding little info, looks like these are the same annoying people that hard-sell magazine subscriptions from different numbers.  The registered location shows a vacant lot where the number is assigned.  Once they get enough complaints and spam blocks, they simply get a new number.  Hate their tactics.