Speex is a patent-free compression format designed especially for speech. It is specialized for voice communications at low bit-rates in the 2-45 kbps range. Possible applications include Voice over IP (VoIP), Internet audio streaming, audio books, and archiving of speech data (e.g. voice mail).
Sofia-SIP is a SIP user agent library, compliant with the IETF RFC3261 specification. It can be used as a building block for SIP client software for uses such as VoIP, IM, and many other real-time and person-to-person communication services. The primary target platform is GNU/Linux. Sofia-SIP is based on a SIP stack developed at the Nokia Research Center.
The CommuniGate Pro Community Edition provides a single address and identity for all forms of Internet communications. You can check your e-mail, chat with colleagues via Instant Messaging and VoIP, view multiple calendars (and other presence features), maintain address books, and view streaming RSS news feeds, all through the powerful Flash-based interface.