I received a call from this number 650-209-6132 at about 12:50pm and ID said "Unavailable" and left no message.  After looking up the number online it seems that its from GB Catering and Bartending Service in Los Altos. I am not
sure it really is since I did not call it back and recommend not answering nor calling it back as it could be a scam.

Same call and hang up--same info found on Los Altos origin of mumber

Recieved call just a few minutes ago from a man identifying himself as having worked on our heater in 2011. I told him that
couldn't be since we did not have any type of heating/duct work done at that time. As always with these calls, caller hung up. SCAM! Number on internet is associated with a company called GB Catering and Bartending Service in Los Altos. PHONEY number!

Clean your vents scam for $39.  Essentially you pay them $39 to come and sell you something.  There is a sucker born every minute.  The last time I bit on this is when I ordered a health newsletter subscription on the Internet and paid them to sell me vitamins!!!

Caller said it had been over 18 months since they serviced our furnace and wanted to send someone out.  Scam !