I’ve been trying out Skype, a new P2P telephony program.
The main advantage Skype has over existing internet telephony solutions is that it works even when both parties are behind a NAT or firewall device that prevents incoming connections. It does this by passing the packets via a third computer running the software that is not firewalled.
It really works well. Latency is very low, even between Belgium and Japan. In fact, there’s less lag than on a regular international phone call.
Best of all, of course, is the fact that it is free to use.