Caller ID says "Hull   MA".  They leave no message.

I call back after hours (using *67 to block my number).  I hear, "Sorry we missed your call.  If you received it, it's an appeal from VETS, a charitable organization.  If you would like a return call, leave your name and number.  If you prefer we do not call you again, please, leave your number you want to be placed on the do-not-call list.  Thank you.  Have a great day."  I leave no message of any kind.

Their name is real short and generic.  This makes it harder to determine which charity they actually are.  I don't know if this is a group of veternarians, veterans, or something else.  This is a bad sign.  They spoof their caller ID and leave no message, more bad signs.

Probably it's a SCAM charity representing veterans.  I get a lot of calls from veterans' charities virtually all of them appear to be scams.