Project revival: TwoSquares is preserving GNU Telephony's history and preparing an open-source revival. Contributors and collaborators are welcome.
GNU Telephony
Open-source telephony, preserved and being revived
Historical archive and independent revival

GNU Telephony: Preserving Open Communications, Building What Comes Next

GNU Telephony belongs to an important chapter in free software history. This independent website reconnects historical technical references and creates a careful foundation for future open-source work.

What was GNU Telephony?

GNU Telephony, also called GnuComm, was an ecosystem of free-software components for telephone services, signalling protocols, real-time media, scripting, and communications application development. GNU Bayonne focused on telephone and voice-application services. GNU SIP Witch addressed SIP-based infrastructure. GNU ccRTP supported real-time media transport, while ZRTP-related libraries addressed media-session key agreement. Common C++, uCommon, ccScript, and ccAudio supplied supporting application facilities.

It was not a single consumer calling application. Understanding the distinct roles of servers, transport libraries, security protocols, and application foundations is essential when reading the older material.

Explore the historical projects

These are independently written historical explanations. Recovered originals are identified separately with their authorship, date, version, and licence.

Umbrella Architecture & Ecosystem

GNU Telephony Ecosystem

The overarching initiative created to provide a complete, free software telephony and voice communications infrastructure, evolving from GnuComm to address VoIP, encrypted media, and decentralized routing.

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Secure Peer-to-Peer SIP Server

GNU SIP Witch

A pure SIP-based office telephone server and peer-to-peer call routing daemon designed to enable secure, direct audio/video communication while bypassing corporate and government surveillance intermediaries.

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ZRTP/SRTP Media Encryption Library

GNU ZRTP (libzrtpcpp)

The standard GNU implementation of Phil Zimmermann’s ZRTP protocol (RFC 6189), enabling Diffie-Hellman key exchange over RTP to establish authenticated SRTP sessions with Short Authentication String (SAS) verification.

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Decentralized Secure Voice Architecture

GNU Free Call

Announced in March 2011 as a community response to centralized telecommunications and proprietary networks like Skype, GNU Free Call aimed to create a resilient, serverless, peer-to-peer encrypted telephone network.

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Telephony Application Server (IVR)

GNU Bayonne

The foundational GNU telephone application server supporting Interactive Voice Response (IVR), voice messaging, conference bridging, and automated call processing over PSTN, ISDN, Dialogic hardware, and SIP.

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Real-time Transport Protocol (RTP) Framework

GNU ccRTP

A versatile, high-performance C++ class framework implementing the Real-time Transport Protocol (RTP, RFC 3550) and RTCP control packets, featuring adaptive jitter buffers, QoS monitoring, and multicast support.

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Portable Multi-threaded C++ System Framework

GNU Common C++

A deeply portable, comprehensive C++ foundation library offering cross-platform multi-threading, socket abstractions, memory-mapped I/O, IPC synchronization, configuration parsers, and XML serialization.

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Lightweight Runtime & Telephony C++ Library

GNU uCommon C++

A redesigned, highly lightweight C++ runtime library optimized specifically for memory-constrained embedded VoIP hardware, low-overhead daemon processes, and SIP Witch server components.

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State-Transition Scripting Engine

GNU ccScript3

An event-driven scripting engine used by GNU Bayonne to describe call flows, application states, transitions, and telephony service behaviour.

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Telephonic Audio Processing Library

GNU ccAudio2

A portable C++ class framework for manipulating telephony audio files, sample formats, codecs, and stream-oriented audio data in GNU Telephony applications.

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Voice Application XML Markup Specification

BayonneXML

An open XML dialect and interpreter interface developed for GNU Bayonne to describe interactive voice call flows, audio playback, touch-tone recognition, and external database lookups in a standardized markup.

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An independent revival supported by TwoSquares

TwoSquares is supporting reconstruction of this archive and early planning for a community-oriented open-source initiative. This does not transfer ownership of historical work or imply appointment or endorsement by the GNU Project or Free Software Foundation. Scope, repositories, maintainers, and release dates will be published only when confirmed.

Developers, technical writers, researchers, designers, archivists, and open-source maintainers are invited to express an interest in contributing.

Contact TwoSquares

Primary historical sources

Official GNU Project pages remain the primary references for the historical packages.