ConfluenceVoice

Spatial WebRTC voice for OpenSimulator — a Windows-native voice server so Firestorm and browser-based viewers can hear each other positionally, without Vivox, on any OpenSim grid.

Who this is for

Vivox has stopped taking new signups for its free OpenSim voice service and has announced its end (OSGrid's notice). Grids that already have Vivox set up can still get voice from it today, but nobody outside Vivox knows for how long, so operators need a replacement they control before it stops. The existing WebRTC voice backend for OpenSim (wolfvoice) is built for Linux, with Docker or WSL as the route for everyone else. ConfluenceVoice gives Windows grid operators another option: a single confluencevoice.exe that runs directly on Windows, configured by one .toml file, with no Linux VM, container or WSL layer to install and maintain.

It is not tied to any particular grid or OpenSim distribution. It works with any OpenSimulator that has the os-webrtc-janus addon (upstream OpenSim and OpenSim-NGC include it; older trees can add it). The name comes from the Confluence grid where it was developed and first tested.

Free and self-hosted is the actual difference from the alternatives, not just a preference. wolfvoice is the same idea but needs Linux, Docker or WSL. ThinkVox is a hosted service: free for 10 concurrent users, then priced per tier ($19/mo for 50, $49/mo for 200, $149/mo for 1,000, per their site). Vivox needs no server of your own either, but it's the thing running out — see above. ConfluenceVoice costs only your own hardware and bandwidth, with no account, no per-user pricing and no external service in the voice path, at the cost of running and maintaining it yourself.

Best on a grid where every region speaks WebRTC. That's the configuration this project tests against, and where the checklist in docs/TESTING.md is being filled in. A grid that mixes WebRTC with Vivox or ThinkVox regions works too, but hits a real Firestorm quirk — see "Known limitations" below — that a single-voice-system grid never encounters.

ConfluenceVoice is an independent project, derived from wolfvoice by Wolf Software Systems Ltd, which is used as a donor of code and ideas — this is not a GitHub fork and shares no git history with it. See NOTICE for full attribution. The protocol handling, spatial mixer and session logic are carried over unchanged; what's different is how it's configured and shipped: a plain .toml file next to the .exe instead of environment variables and /etc paths, so it runs like any other Windows program — download, edit one file, double-click.

It is a voice service backend for os-webrtc-janus (original by Robert Adams; Wolf Software Systems maintains a fork at intelligentwolf/os-webrtc-janus). That addon does the OpenSimulator half — capabilities, provider advertisement, session bookkeeping — and ConfluenceVoice is what you point it at instead of a Janus gateway.

Firestorm 7.1.10+  /  browser viewer
        │  ProvisionVoiceAccountRequest + VoiceSignalingRequest   (LLSD caps)
        ▼
OpenSim region  +  os-webrtc-janus addon   ← REQUIRED
        │          forwards the caps onward as JSON-RPC
        ▼
   ConfluenceVoice  ── answers the SDP, terminates DTLS/SRTP/SCTP,
        │              mixes a SEPARATE stream per listener
        ▼
   viewers   (UDP media)

What you need

os-webrtc-janus is a hard requirement. It supplies WebRtcVoice.dll and the region-side capability handlers that everything here depends on. See docs/OPENSIM.md for building it — that side is unaffected by which backend (wolfvoice or ConfluenceVoice) you point it at.

For the voice server (this program)

• Windows, with a public IP address and a DNS name pointing at it. TLS is not optional: the SDP carries the server's DTLS fingerprint, so anyone able to rewrite plaintext signalling in flight could become the media endpoint.
• UDP 40000–40999 open in Windows Firewall (range is configurable — see below). This range is also the ceiling on concurrent sessions.
• TCP 9443 reachable from your region hosts only. This endpoint has no authentication of its own.

For viewers — same as upstream: Firestorm 7.1.10+ works with no configuration; browser viewers need a client speaking the same contract (client/voice_llwebrtc.js is a working reference).

Quick start

1. Get the exe

Build it yourself (see below), or use a release build if one's been provided to you. Put confluencevoice.exe in its own folder — it will create its config file and expects its TLS certificate next to itself.

2. Configure it

Run it once:

.\confluencevoice.exe

The first run creates confluencevoice.toml beside the exe and exits, telling you where. Open it and set at least public_ip:

public_ip = "203.0.113.10"   # REQUIRED — see the comment in the generated file
rpc_bind = "0.0.0.0:9443"
media_port_lo = 40000
media_port_hi = 40999
max_sessions = 900
tls_cert = "tls\\fullchain.pem"
tls_key = "tls\\privkey.pem"

Place your certificate and key at the tls_cert / tls_key paths (relative paths resolve against the folder the config file is in). Run .\confluencevoice.exe again.

3. Open the firewall

New-NetFirewallRule -DisplayName "ConfluenceVoice RPC" -Direction Inbound -Protocol TCP -LocalPort 9443 -Action Allow
New-NetFirewallRule -DisplayName "ConfluenceVoice Media" -Direction Inbound -Protocol UDP -LocalPort 40000-40999 -Action Allow

Scope the RPC rule to your region hosts' IPs if your firewall profile allows it — that port has no authentication of its own.

4. Point os-webrtc-janus at it, and configure the region

Same as upstream from here — see contrib/confluencevoice.ini and docs/OPENSIM.md. Both estate and parcel voice flags must be enabled or nothing will happen and nothing will log — see docs/OPENSIM.md for details.

Firestorm 7.2.4+ needs one more thing: the region must advertise SimulatorFeatures["stun-servers"], or the viewer refuses to start voice and the mic stays greyed out. Set StunServers in the ini (see the template) and use an os-webrtc-janus build that sends the stun-servers key. See docs/TESTING.md.

5. Check it

curl.exe -k https://voice.example.org:9443/
# {"rooms":0,"service":"confluencevoice","sessions":0}

Building from source

Needs a Rust toolchain and cmake (the opus crate compiles libopus from source).

$env:CMAKE_POLICY_VERSION_MINIMUM = "3.5"
cargo build --release
cargo test              # unit tests, no network required

The CMAKE_POLICY_VERSION_MINIMUM variable works around a version mismatch between the opus crate's vendored libopus (which declares an old cmake_minimum_required) and CMake 4+, which refuses that outright. This is CMake's own documented escape hatch, not a fragile hack. Without it the build stops with "Compatibility with CMake < 3.5 has been removed from CMake". Use a recent CMake (4.x) so it also recognises current Visual Studio versions.

The built binary is at target\release\confluencevoice.exe. Copy it, together with your confluencevoice.toml and tls\ folder, wherever you want to run it from.

Status

Working end to end with one live viewer (Firestorm 7.2.5) through an OpenSim region: the peer connection connects, the data channel opens, and the speaking indicator shows. Not yet tested with two or more real participants (hearing each other, spatial panning). Details, problems found and fixes: docs/TESTING.md.

Roadmap

Next, in order:

1. Multi-person testing. Two or more real participants for spatial voice (hearing each other, panning, distance, other people's speaking dots), then group voice and person-to-person calls. Progress is tracked in the checklist in docs/TESTING.md; a release should only claim what is ticked there.
2. A shared secret for the voice port. TCP 9443 now supports an IP allow-list (allowed_region_ips in confluencevoice.toml, checked before the TLS handshake) — done. A shared-secret scheme on top of that is not: the region-side connector (os-webrtc-janus's WebRtcVoiceServiceConnector.cs) has no way to send one today, so this needs a matching region-side change first, not just a ConfluenceVoice one.
3. TURN relay support Done. turn_urls/turn_username/turn_credential in confluencevoice.toml are passed to viewers as a relay of last resort. Verified that a configured TURN server doesn't break normal connections; not yet verified against a real TURN server actually relaying media for a viewer that needs one.

After that:

4. Easier setup for operators. Get the stun-servers fix into upstream os-webrtc-janus (Firestorm 7.2.4+ needs it), a Windows guide to getting a free TLS certificate, a firewall setup script (PowerShell commands exist in this README; not yet a standalone script), automatic public-IP detection, and a Vivox-to-WebRTC migration guide for grids that mix both.
5. Reliability. Done: a status endpoint (GET /) reporting version, uptime, session counts, cumulative skipped-tick count, and whether auth/TURN are configured; config validation that rejects bad IP entries and incomplete TURN setup at startup with a clear message; and a local admin page (admin_bind in confluencevoice.toml, loopback-only by default) with a live status view and Stop/Restart controls. Still open: a TLS certificate expiry warning on the status/admin page (so a lapsed cert doesn't silently take voice down), log to a file with rotation, certificate reload without a restart, and a documented Task Scheduler or NSSM recipe for starting on boot.
6. Distribution and trust. Done: automated Windows builds and tests on every push (ci.yml), and a release workflow (release.yml) that builds, packages and publishes a GitHub Release from a version tag. Still open: code signing so SmartScreen does not warn (needs a certificate), and a winget or Scoop package.
7. Moderator mute. Estate and group moderators muting another person, a feature Vivox had. The protocol field exists; the server currently always reports it as false.

On hold: a Windows Service wrapper (start automatically, no console window). For reference when this resumes: wolfvoice's contrib/wolfvoice.service restarts on crash (Restart=always, 2s delay), bounds memory to 2G "to bound a runaway rather than size normal use," and sandboxes the process heavily (ProtectSystem=strict and similar) — worth carrying the same intent into whatever Windows equivalent gets built, not just the "starts automatically" part.

Testing it without a viewer

# Correctness: two synthetic viewers, real SDP, real Opus, real mixing.
cargo run --release --example two_clients -- https://127.0.0.1:9443

# Capacity: N clients, M speaking, reports service CPU.
cargo run --release --example load_test -- https://127.0.0.1:9443 40 20

Run these on the voice host. Point two_clients at a public_ip that is a real, bindable address on the machine (a loopback address won't gather a matching ICE candidate on the client side — that's an ICE property, not specific to this service).

What's carried over from wolfvoice, unmodified

• src/mixer.rs, src/proto.rs, src/room.rs, src/session.rs — the spatial mixing math, wire protocol and session/room bookkeeping. None of it is Unix-specific.
• docs/PROTOCOL.md, docs/CLIENT.md, docs/OPENSIM.md, client/voice_llwebrtc.js — protocol reference, viewer support notes and the region-side addon, none of which depend on which OS runs the voice backend.
• examples/two_clients.rs, examples/load_test.rs — the end-to-end and capacity test harnesses.

What's different from wolfvoice

• Configuration: confluencevoice.toml next to the exe, not WOLFVOICE_PUBLIC_IP and hardcoded /etc/wolfvoice/tls/... paths (see src/config.rs).
• No installer, no systemd unit: this is meant to be run directly, the way any other Windows program is. A Windows Service wrapper (so it can start automatically and run without a console window) is not implemented and is on hold for now; run it from a console, or start it yourself with Task Scheduler.
• Session IDs are prefixed cv- instead of wv-; the health endpoint reports "service": "confluencevoice". Everything on the wire to Firestorm/OpenSim is unchanged — those prefixes are purely internal/log labels.

Known limitations

Mixed grids. On a grid that runs WebRTC regions next to Vivox or ThinkVox regions, Firestorm's Vivox client can stop for the rest of the session after visiting a WebRTC region, so voice fails in the Vivox regions until voice is toggled off and on in Preferences → Sound & Media → Voice (no relog needed). This is a Firestorm behaviour, not something ConfluenceVoice can fix on its own — a region-side workaround (letting the region's Vivox and WebRTC modules answer requests together) has been tried on one grid's os-webrtc-janus build, not upstreamed here yet. A grid running WebRTC only, with no Vivox or ThinkVox regions, does not hit this. Details in docs/TESTING.md.

• TURN is supported but unverified against a real relay. confluencevoice.toml can point viewers at a TURN server (see Roadmap above) — unlike upstream wolfvoice, which has no way to add one. Without one configured, the situation is the same as upstream: Firestorm hardcodes its own STUN servers to stun:stunN.<grid>.secondlife.io, which don't resolve outside Second Life, so media still connects in the common case (the server advertises a routable host candidate and learns the viewer's address from the connectivity check), but a viewer whose network blocks outbound UDP entirely gets no voice.
• Single instance. If ConfluenceVoice is down, voice is down everywhere it is configured.
• Group and IM voice (channel_type: multiagent) is implemented and rooms are keyed correctly, but has had far less exercise than spatial voice.

Alternatives

Other ways to get voice on an OpenSim grid now that the built-in Vivox connector no longer works for most operators. Facts below are as of September 2026; check each project's own pages before relying on them.

• wolfvoice — the project ConfluenceVoice is derived from. Same WebRTC design, self-hosted and free. Built for Linux (a Linux host with systemd); on Windows it means Docker or WSL. Choose it if your voice server is Linux.
• ThinkVox — a hosted, paid service (a free tier and tiers priced by concurrent users) with a web dashboard and an API key; its signup works much like Vivox's did. Firestorm 7.1.10+ uses WebRTC with nothing to install. For older Firestorm it asks users to swap in a replacement SLVoice binary, and the download its onboarding offered was for Linux x64. Choose it if you would rather not run a voice server yourself.
• ConfluenceVoice — self-hosted and free, a single .exe on Windows, with no per-user pricing and no third-party service in the voice path. Firestorm 7.1.10+ uses WebRTC natively, so viewers need no replacement files.

Credits

Built on wolfvoice by Wolf Software Systems Ltd for the Wolf Territories Grid, which is itself built on os-webrtc-janus by Robert Adams, which brought WebRTC voice to OpenSimulator. See NOTICE for the full chain.

The wire protocol is Linden Lab's, as implemented in Firestorm.

Licence

Apache License 2.0 — see LICENSE.