How can you make a free phone call? Download Skype, go to a coffeeshop with free Wi-Fi access, and dial anyone else who has a Skype phone.
While we are still a few years away from ubiquitous free calling (and free Internet access for that matter) this day is likely to come sooner than later
Jeff Jarvis has a report on an article by Eli Noam, a Columbia professor, in which he argues that:
the entire information sector - from music to newspapers to telecoms to internet to semiconductors and anything in-between - has become subject to a gigantic market failure in slow motion. A market failure exists when market prices cannot reach a self-sustaining equilibrium. The market failure of the entire information sector is one of the fundamental trends of our time, with far-reaching long-term effects, and it is happening right in front of our eyes.
Eli seems to take this as a negative, while I tend to think in terms of Joseph Schumpeter's concept of Creative Destruction -- the deconstruction of these industries is enabling an entirely new generation of technologies an industries to evolve.
In the future we will pay for certain aspects of connectivity -- reliability, security, and performance. Like drinking water, in the western world basic access will be ubiquitous (it may just taste funny) and you will pay for the higher quality bottled stuff. Telephony will become just "...a voice application, completely indistinguishable from any other kind of application that can run on an IP network..." (Michael Powell, Chairman of the FCC)