Caught by my spammer filter.

If I had to guess, it was from air duct cleaning services again using a spoofed caller ID.

Air duct sxcammer or spammer? - calling my medical office number on a Sunday afternoon. Caller sounds identical to many other air duct calls over a long period of tiem.  Can there really still be dirty airducts around with all this activity - or is there something sinister as well as annoying about these calls.

I amon the National DNC list, but it seems to afford no protection