I get no ping repsonse to my phone. Why? I went to www.whatsmyip.org and got my public IP address for my phone.  Just for kicks and grins, I tried to ping it, but didn't get a reply.  Is ICMP turned off on my android phone?
Either your phone silently drops pings, or the router it's behind, either your wifi router, or the 3G network's router that NATs your phone drops them.