No they are not legitimate salesmen.  They are scamers.  They are not associated with Google Plus.  Do not give these people any information.

sick of this number calling five times a day!

same thing . caller says nothing, then hangs up .. if you call them back . " if you want to be put on the do not call is press 1. ...

This number and about 4--5 others like it (scams) call my house up to 3 times EACH a day and my cellphone 2 times a day. So freaking sick of them!!! What is the point of going on the "DO NOT CALL LIST" if these a**holes call anyways. Getting ready to change both home and cell number. Anyone know how they got our info to begin with or do they have a computer that just randomly calls a number and keeps calling till they get an answer?

The auto dialers call hundreds of random numbers at once, hoping something goes through. I've heard that hang-up calls are done to see if the line is active. If the call is answered, it's flagged as an active number to be called over and over again with a real person on the other line. I accidentally answered one of these last week (it was a local number; I thought it might be one of my sons' friends) and have been inundated with calls since.