Caller ID says "Cambridge MA". They leave no message.
I call back after hours (using *67 to block my number). I hear the following, "Thank you for calling the FOI (???) program information line. Please, leave your name and number that you wish to have removed from the calling list. I'll record your message at the tone. When you're finished hang up or stay on the line for further options." I did not leave my name or number as this can actually make things worse.
The "FOI" part seems strategically mumbled; my guess is that they don't wish to be identified. So they spoof the caller ID and do not really identify themselves on their outgoing message. Smells like a SCAM.