What do you mean "block all google-voice numbers"?
As in automatically removing them from posts? That would be very stupid because some people use their Google Voice number exclusively, and it shouldn't be up to them to decide how I should be contacted.
It's very annoying, they do it to combat spammers but as an innocent user I get hit all the time with the phone verification.
Craigslist requires that your number be identified as "Fixed Line" or "Mobile" (not "Non-Fixed VoIP" or "Prepaid Mobile") by their provider, ReduceFraud.com, in order for you to be able to complete phone number verification and post in certain sections on CraigsList.