From DSL Wiki

Application type: Real-time Transport Protocol(RTP) Frontend

Gnome-o-phone (gphone for short) is an internet telephone. In other words, if you and your friend have computers with sound cards and network connections, you can use gphone to talk to each other and save on phone bills. Gphone is definitely a work in progress and you probably shouldn't bet your business on it; if it breaks you can keep both pieces. Don't be too hard on the program, though -- the user interface is a bit rough but gphone does work pretty well.

External links

Project Web Site
Oops, looks like some folks connected with the Android (mobile device platform) got to the Wikipedia gphone article title before the Gnome-o-phone folks did. If you studied the Gnome-o-phone Project Web Site and wrote a Gphone disambiguation page and a Gnome-o-phone article, the folks working on the Gnome-o-phone project would probably welcome you to their community with open arms.
In the mean time, if you want some background on Gnome-o-phone other than that provided at the Project Web Site, you might read and understand the Real-time Transport Protocol(RTP) Wikipedia article.