While stroking their neckbeards and drinking Mountain Dew?
There are free services for voice, video and text chat.
What is more difficult, politically speaking, is producing a free client for the Skype protocol. Clean-room reverse-engineering the protocol and producing a client that uses it without Microsoft raining down upon the project is not just a technical problem (or of not switching to cake).
The FOSS community weren't some hungry peasants that the aristocrats at Richmond took their bread away.
On the contrary, they were shouting how they don't need those stinking "proprietary" products, and that they can do one better.