If ther information provided by others is correct, suspect scam unless you have stock directly involved in a proxy fight for shareholder votes and can respond without divulging confidential information. If you never vote you shares in any stocks, just add them to your do not call list or block their phone number. With some companies issues put to a vote automatically fail if less that a required number of shareholders and/or their stocks are voted, which in my book iis just as well. Most boards propose measures that in my opinion are self-serving to members of the board.
No message was left. The category list should include not elsewhere classified because the choice is not comprehensive enough of unwanted phone calls.