Your wireless provider probably does not allow servers and services on its 3G network. On the technical side, it is quite likely that your provider does not assign an IP address to every phone, rather it probably directs queries towards a server which functions as a NAT gateway for many phones on the network. The IP address you're trying to connect to wouldn't belong to your phone, but that server; just as if you were trying to connect to a server behind your home router.
More information on cellphone IP addresses here.
