Every digital voice mode I’ve covered in the Evolution of Amateur Radio series, D-STAR, DMR, System Fusion, shares one thing in common: they all rely on the proprietary AMBE voice codec, a patented chip that every manufacturer has to license. M17 exists specifically to get away from that dependency.
A protocol built to be genuinely open
M17 uses Codec 2, the same open-source voice codec behind FreeDV, instead of AMBE, meaning there’s no patent licensing fee baked into every radio or hotspot that implements it. The protocol itself, not just the codec, is published as an open specification, which means anyone can build compatible hardware or software without negotiating a license agreement first, something none of D-STAR, DMR, or YSF can fully claim given their AMBE dependency.
Where you’ll actually find it
M17 support is still mostly a hotspot and software-defined story rather than something you’ll find in a mainstream commercial radio. MMDVM-based hotspots have added M17 support alongside their existing DMR, D-STAR, and YSF modes, and a small but growing set of dedicated M17-capable hardware projects exist for hams willing to build or flash their own gear. It hasn’t reached anywhere near the adoption of the three established modes yet.
Worth watching, not worth switching to yet
I wouldn’t recommend building a station around M17 today if your goal is reliably reaching other hams on local repeaters, the infrastructure and user base just aren’t there yet. But if the AMBE licensing situation bothers you philosophically, or you like tinkering with genuinely open protocols, M17 is worth keeping an eye on as it continues to mature.
Related reading: FreeDV · Packet Radio · What Is P25 Digital?