How do they perform this due diligence? Is there a way to tell if a number is a Google Voice number?
This seems like an insane way to vet potential developers, by the way. Someone who bases a hiring decision on what brand of phone service your employee/contractor has chosen is probably not looking at the right metrics.
I haven't used google voice, but since the article mentioned that the client was not satisfied with a google voice number I assumed they must have had some way of knowing.
You can take all sorts of little clues from these kinds of things. For example if a website is phrased and designed to look corporate but the only number published is a mobile and the email address ends in @hotmail.com then you know you might be dealing with a single freelancer.
This seems like an insane way to vet potential developers, by the way. Someone who bases a hiring decision on what brand of phone service your employee/contractor has chosen is probably not looking at the right metrics.