Baraza is a free mobile instant messaging server for Linux, supporting the Open Mobile Alliance's Instant Messaging and Presence Service (IMPS) protocols (also known as "Wireless Village"). IMPS is supported natively by a wide variety of mobile phones (particularly Nokia and SonyEricsson). The server also supports Jabber/XMPP messaging for inter-domain message exchange (a.k.a. federation).
Gizmo Project is a program that uses advanced VoIP technology to allow you to talk with your friends around the world. Gizmo Project uses your Internet connection to make calls to people using other computers. It is simple, and allows you to talk clearly and for as long as you want.