Voicemail left on my office phone to call Greg Klein back at this number. No other information. However, Spokeo.com has this number registered to Carl Hagenmaier in Mountain View, CA. Maybe when you return the call you can ask for Carl and see what happens.
Called and it was Dave Klein. He went to voice message and by the looks of the previous notations, was going to try and sell me on something I do not want. Also note that he did ask for a call back, but did not leave information on who he is with or what the call was to be about.
I got the same voice mail. No message other than "call back (415) 941-5205." I'll assume he's just another predator / on-line sex criminal / scam artist / financial-services company rep.