Mumble is an excellent alternative to Vivox voice, which is the default method of speaking with others in OpenSimulator Viewers.

To know more about how Mumble can be used in OpenSimulator, read this article: Mumble voice for opensimulator.

You can already use HG MumbleVoice on HG Safari Grid with the basic services, called Solution 2 in the article mentioned above.
HG Safari Grid is currently experimenting with a new Solution 5 using Bianconiglio, a HUD co-Viewer application.
Bianconiglio is completely developed on HG Safari Grid and focused on OpenSimulator.

The main features of HG MumbleVoice are:

✳️ parcel based voice, allowing for privacy
✳️ conference voice calls
✳️ lip movement
✳️ 3D spacial voice ✳️ sounds for voice events
✳️ profile picture & text
✳️ avatar tag
✳️ voice effects

Mumble is free, opensource, and awesome!
Bianconiglio is free, it will be opensource, and will include many useful tools!

HG MumbleVoice and Bianconiglio are entirely independent of any changes made in the development of the third party Viewers.
On the OpenSimulator side, it only impacts on the OptionalModules (OpenSim.Region.OptionalModules.dll).

HG MumbleVoice can work alongside other Voice options like Vivox, WebRTC, etc. and it offers residents a backup should any other Voice services fail.
HG MumbleVoice is created to work across an entire grid. Different grids can each have their own voice system.
The grid does not depend on external servers, each one handles its own voice server.

Mumble

Mumble is a free, open source, low latency, high quality voice chat application.
The architecture of Mumble is constituted by a server (Murmur) and a client (Mumble Client).

Them main features are:
✴️ Free & Open Source Software (FOSS)
✴️ Very low latency (60 ms)
✴️ Good sound quality (15.8 - 144.0 kbit/s)
✴️ Default quality is 58.8 kbit/s
✴️ Audio codec: CELT, Opus
✴️ Voice pre-processing to remove noise (Speex)
✴️ Public/private-key authentication by default
✴️ Positional audio (PA)
✴️ Extensive user permission system (ACL)
✴️ Extendible through Ice protocols
✴️ A totally configurable tree of audio channels
✴️ Over 100 simultaneous voice participants
✴️ self hosting
✴️ Low resource cost for hosting

MuMo

Mumble Moderator (MuMo) is a framework that simplifies the development of plugins that connect to Mumble servers via ICE.
MuMo is created in Python and can be easily extended with modules.

This is only a partial history.

📌️ 2024: Snowbody Cortes starts the HG MumbleVoice project on HG Safari Grid.

📌️ 2023: CyberGio CyberStar documented his experiments with Mumble v.1.4.287 in his grid.

📌️ 2022: during a visit to Atlas grid, Jeff Kelley explains how they use Mumble on their grid.

📌️ 2018: around this year, EchoVoice project was presented at the OSCC conference by Lisa Laxton and Frank Rulof. Since then, there have been further developments anounced at the OSCC (e.g. OSCC19). In 2025 there will be a new presentation at OSCC.

....

📌️ 2011: Ange Mange on Francogrid writes about Mumble: Installation et test de Mumble : Murmur/Whisper sur opensim.

📌️ 2011: Aurora Sim Development Team (AuroraSim is a fork of OpenSimulator) experiments with Mumble by cloning the Whisper repo on GitHub to create a MurmurVoice.dll for Aurora v.0.2.

📌️ 2011: Volker Gaessler (VCOMM) with the Whisper project integrates Mumble in OpenSimulator v.0.7.1+, as described here. Source code on GitHub.

This is only a partial chronology.

📌️ 2025: Canadian Grid is collaborating with Misterblu Waves to bring WebRTC functionality online here but the grid is not Hypergrid accessible.

📌️ 2024: SecondLife voice support is changing from Vivox to WebRTC. At OSCC24, Misterblu Waves takes part with his presentation, He experiments with WebRTC and Janus server on a region in OSgrid, and in December, Ubit Umarov and AI Austin visit it. Details and updates here.

📌️ 2022: Vivox voice replacements delayed by funding and OpenSim integration issues here

📌️ 2021: Vivox is no longer giving out accounts to new OpenSimulator grids, and existing grids are considering how long this free service will remain available here and are exploring possible alternatives here.

....

📌️ 2011: Vivox accounts are given for free and OpenSimulator grids start to use them. Maria Korolov writes this article: Free Vivox for all.