The caller says they are calling to confirm my appointment to discuss my retirement. I have made no such appointment. They persist by telling me that it doesn't hurt to get another opinion. I have declined, but continue to get calls.

It IS a legit STRS (State Teachers Retirement outfit) trying to set up an appointment based on a client's request.  I ignored the call, too, but thankfully, they left a voice mail with the same number and I remembered that I did request an appointment online. a couple of weeks back.

You sound like a shill to me.