I am thinking of building Android apps that can communicate to each other - e.g. IM or game. As with any Java/Android, there is a suite of TCP/UDP communication library i can use.
Question is this: Android devices normally are connected via the Telco network, and Telcos normally have firewalls/NAT routers which makes direct connection to an Android device impossible.
Are there anyone out there who manage to use sockets to connect 2 devices directly ?