FON is a router software program that allows people to synchronise their WiFi broadband access all over the world.

Participants are called `Foneros’ or "Foneras", falling into three categories: Linus, Bill, and Alien.
A Linus is any user who shares his/her WiFi in exchange for free access
throughout the Community wherever there is coverage. A Bill is a user
who, instead of roaming
for free, prefers to receive 50% of the fees that FON charges to
Aliens. And Aliens are those users who do not share their WiFi access
and therefore must pay FON a modest fee every time they connect through
a Fonero access point. Thus the system can be described as a peer-to-peer sharing service, which we usually relate to software.

Based in Spain and led by the Argentinean entrepreneur Martin Varsavsky (founder of Jazztel), FON was unveiled at the O’Reilly Emerging Telephony Conference, held between January 24-26, 2006 in the United States. At present, the software is still in an experimental Beta phase and is only available for Linus.

Although FON has received some financial support by companies like Google and Skype,
it remains to be seen whether the idea can actually work. There are
three main challenges for this type of service at the moment. The first
is that it needs much media and community attention in order to get
through the "early adoption" phase and into more mainstream use.
Second, sharing your Internet connection is often against the terms of
use of your ISP
(Varsavsky has since stated that ISPs will receive a fee if they allow
FON use, which may affect this). This means that in the next few months
we can see ISPs trying to defend their interests in the same way music
companies united against free mp3 distribution. Finally, the FON
software is still in beta and users will need time to make sure it is usable and doesn’t present any serious security issues.

There has been some criticism tied to the fact that FON introduces
itself as a movement, which may lead to think that FON is a sort of
user-based association when it is in fact a corporation.

wikipedia.org