Use GTalk2VoIP to make SIP calls behind firewalls

A useful feature of GTalk2VoIP is that it can be used to make VoIP calls behind firewalls, which block VoIP ports. And GTalk2VoIP itself is an excellent product to make VoIP calls to other IM networks (MSN, Yahoo! and so on) as well as normal landlines and cell phones via Google Talk.

Talkonaut — IM and VoIP client on Java mobile phones

Talkonaut is a powerful IM and VoIP client on Java mobile phone. Maybe you have already heard about it. But the latest version 3 has lots of improvement in features, stability, user interface and speed.