Linphone Desktop is a production-grade, cross-platform SIP softphone built on the Linphone C++ SDK and wrapped in a Qt6/QML user interface. It delivers audio/video calls, instant messaging (including group chat, file transfer, reactions, and ephemeral messages), conference scheduling, call recording, and presence management across Windows, macOS, and Linux. The architecture follows a strict MVVM split: model classes run on the Linphone SDK thread and expose Qt signals, while GUI-facing 'Core' classes live on the main thread and communicate with models via a custom SafeConnection template that enforces thread affinity. QML views bind directly to these cores, with list proxies (e.g., ListProxy, SortFilterProxy) providing paginated, filterable models for contact lists, call history, and chat logs. The codebase also integrates advanced features like OIDC/OAuth authentication, LDAP/CardDAV address book sync, end-to-end encryption (LIME/DTLS/SRTP), and system-level integrations (toast notifications, tray icons, screen-sharing, autostart) with per-platform backends. The repository is actively maintained with a modern build system (CMake), comprehensive GitLab CI pipelines (Linux, macOS, Windows, Squish GUI tests), and a substantial localization effort (multiple .ts files).
tSIP is a Windows-only SIP softphone application built on top of the baresip SIP user agent framework, which itself relies on the re (libre) and rem (librem) networking and media libraries. The repository bundles a large number of third-party libraries as source code: Opus, Speex, G.722, GSM, FFmpeg, OpenSSL, WebRTC audio processing, ZRTP (GNU ZRTP), PortAudio, SDL2, Scintilla, Lua, and JSONcpp. The tSIP GUI is written in Borland C++ Builder VCL, with forms for call management, contacts, history, programmable buttons, hotkeys, Lua scripting, and configuration. The architecture is a classic Windows desktop application with a modular plugin system for codecs and media sources. The codebase is a snapshot from around 2012-2015, with many outdated libraries and compiler-specific code, making it high-risk for reuse without significant modernization. It is not a data research project; it is a full-featured VoIP client.