Caller ID says "MED HEALTH SOLU".  They leave a 1 second blank message each time.  They call 3 times in under a minute.

I call back after hours (using *67 to block my number).  I hear the following, "Thank you for calling Medical Health Care Solutions.  I'm sorry that the operator is not available to take your call.  The operator is available from 9 AM until 4:30 PM each business day.  If you know the extension number for whom you are calling, please, press the 3 digits now, or press 0 and leave a message in our general delivery mailbox.  Your message will be retrieved on the next business day.  If this is a computer emergency requiring immediate assistance, please, press 9 now to be redirected, or call our 24 hour emerency number directly at 978 886 2845.  Thank you and have a nice day."

I call the computer assist number to find out why I may have been called.  They do medical billing for Beth Israel doctors in Massachusetts, so his best guess is that it concerns a medical bill.