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.
Your phone can have a lot of different IP's on different interfaces but that one is not yours. It's internet gateway of your mobile operator.
If I'm wrong consider the point of describing to customers why they should pay for some pings or face the hell of ICMP incapsulation of freebies masters.