igtoth / sidetone

Sidetone 
 A SIP softphone built for troubleshooting: place the call, see the ladder, and know why it failed. 
 Test calls over UDP or WebRTC, pcap and pcapng analysis, RTP quality and MOS, plain-language diagnostics, 
 an AI second opinion with your own keys, automated test suites and an MCP server, for Windows, macOS, Linux and the browser.
 Download ·
 Open it in the browser ·
 Test suite examples ·
 Contribute 
 Alpha: expect rough edges. A capture that Sidetone reads wrong or a finding that misleads? Open an issue with a redacted pcapng (Export › Redacted pcapng): real traces are what improve the rules most. 
 Three lines, two of them in a local conference, Opus on the wire, BLF lamps, every event and result in plain words. 
 Features ·
 Everything in the box ·
 Automation ·
 AI ·
 Under the hood ·
 Get started ·
 Help wanted ·
 Downloads 
 A real softphone 
 Several accounts and lines, hold, mute, blind and attended transfer, DTMF three ways, DND and auto answer, call forwarding, a voicemail lamp, SIP MESSAGE, microphone and speaker. SIP over UDP from the desktop, or over WebSocket with WebRTC from the browser.
 It explains the call 
 Around 40 deterministic rules read signaling and media and say what went wrong in words: missing ACK, NAT in SDP, one-way audio, codec mismatch, loss and jitter, with the message numbers as evidence.
 Evidence you can share 
 Annotated pcapng with findings as Wireshark packet comments, TLS keys embedded when available, and a redacted export that masks numbers, names, credentials and public IPs.
 Built for troubleshooting 
 A live SIP trace, every packet captured without a driver, DNS SRV and NAT checks, and a CLI, JSON test suites and an MCP server so scripts and AI agents can do the same.
## Features
Every screenshot is Sidetone itself, captured headless by
`scripts/readme-shots.mjs` against the throwaway PBX in `lab/` and the
built-in sample captures, with a test tone instead of a microphone. Some
are in the dark theme (the Theme button, or your system setting).
 The live SIP trace: every request and response as it happens. 
 See the wire while you talk 
 Each message the phone sends or receives appears at once with its time, direction and peer; responses are coloured by class. Filter by number, method or Call-ID, hide the REGISTER and OPTIONS noise, pause, save the session as pcapng, or open it in the analyzer with one click.
 A remote worker behind NAT: 200 OK retransmitted ten times, no ACK, drop at 32 s. 
 The ladder, with the diagnosis on it 
 Calls you make are captured and analyzed with the same engine as any pcap or pcapng from Wireshark, tcpdump, sngrep or an SBC. Dialogs are grouped by Call-ID; the ladder marks retransmissions and colours each response class; a dot shows which messages a finding points to.
 The INVITE that started it: private Contact and private SDP address. 
 About 40 rules that explain the call 
 Missing ACK, NAT in SDP, one-way audio, codec mismatch, failed authentication, glare