Who called from 4087154900

Got an empty message on my answering machine. Not expecting anyone calling me from this area code.

unanswered call

I have the same problem, they called me and once i answered they didn't respond, then I call back, the message they have is " I'm sorry".

please anyone explain what is going on?

Whois phone:
Type: Land Line
Provider: Pac - West Telecomm
Location: San Jose, CA

(408) 715-4900 is from OAKLAND, CA 94612-2897. I am working on acquiring the exact street address.

I keep getting random calls and when I answer the phone all I get is a series of electnonic beeps.  Today was the first time I was able to capture the incomming number