Thank you 800notes web site. I was able to identify this previously unknown caller as the San Jose Mercury newspaper. Since I use Google Voice, I programmed this number to go directly to voicemail---no more ringing my cell phone.
Kept getting calls from this number but not able to get to them. They never left a message. So I called over and over. At first, nothing. Then a recording finally came on and said "if you received a call from this number, it's in regard to a magazine subscription and if you want to have your number removed from the call list to leave a message. But....I tried several times and it says it's full and cannot accept any more messages.