Wengo: Open Source VoIP

One of the potential obstacles to adopting open source is the absence of important or even critical applications. A case in point is VoIP. Although, to its credit, Skype offers a client for GNU/Linux, it's not open source. So what do you do if you really need VoIP but also want to follow the path of light?

Enter Wengo, which not only offers the client, but makes all of the code available under the GPL. I've no idea what the VoIP is like, but Wengo is certainly doing the right thing as far as the software is concerned. (Via LXer and Free Software Magazine.)