SIPSorcery is a comprehensive real-time communications library for .NET implementing SIP, WebRTC, RTP/RTCP, STUN/TURN/ICE, DTLS-SRTP, and SCTP protocols from scratch. The core library (src/SIPSorcery) provides SIPTransport for signaling, RTCPeerConnection for WebRTC, RTPSession for media transport, and media endpoint abstractions (IAudioSink, IVideoSource) for decoupling capture and rendering. Satellite projects include SIPSorceryMedia.Abstractions (media interfaces), SIPSorceryMedia.FFmpeg and SIPSorceryMedia.Windows (codec backends), SIPSorcery.VP8 (a C# port of libvpx VP8), SIPSorcery.OpenAI.Realtime (OpenAI Realtime API client), and a CLI tool (SIPSorcery.Cli) with route/bridge commands for wiring media pipelines between SIP, WebRTC, and cloud realtime endpoints.
aTox is an Android client for the Tox peer-to-peer instant messaging protocol. It provides encrypted text messaging, audio/video calls, file transfers, and group chats using the decentralized Tox network. The application follows a clean multi-module architecture: the `domain` module contains pure Kotlin business logic (Tox wrappers, feature managers, validators), the `core` module handles local persistence via Room database (contacts, messages, file transfers, friend requests), and the `atox` module implements the Android UI using Dagger dependency injection, ViewModels, LiveData, and Navigation component. Key entry points include `MainActivity` for handling intents and navigation, `ToxService` for running the Tox loop in a foreground service, and `EventListenerCallbacks` for bridging Tox events to database updates and notifications. External dependencies include the `tox4j` JNI bindings to `c-toxcore`, libsodium for encryption, and opus/libvpx for audio/video codecs. The repository is explicitly unmaintained and carries significant technical debt from its complex Bazel native build system, outdated library versions, and potential security risks inherent in the Tox protocol itself.