Googled the number and found numerous links to other ad sites... I'm thinking misscox is pretty legit at this point. The only thing that struck me as odd was the number was also shared with a provider in Las Vegas which is a bit strange. Thinking I'll book this week though. Fingers Crossed...
I wonder if one of the other high-profile providers on the site would get in touch with her and vette her? That would be a sure way to get the ball rolling.
Keep us posted on how it goes- what city or area are you seeing her in??