Open protocol · Codec 2 · callsign routing · reflectors
M17
M17 is part of the experimentation and interoperability layer. Treat current clients, reflectors and network behavior as moving parts and verify them against primary project sources.
Experimental does not mean undocumented.
iOS field client
MSeven - M17 (M7)
MSeven changes the iOS picture enough that it deserves to be named, not buried as “M17 decoder.” The current app connects directly to M17 reflectors for licensed amateur use, receives and transmits, shows the transmitting callsign, keeps recent station activity, supports station mapping and contact notes, and has CarPlay/audio features. Current releases also support direct-to-RF connectivity through compatible Mobilinkd TNC 3/4 and a radio that exposes the required 9600-baud KISS/discriminator path.
That makes MSeven a field client with both network and supported RF possibilities. It does not replace the FT-5DR/openSPOT path. It adds another useful route into the open M17 network and gives the phone an actual M17 job today while QSO One iOS remains forthcoming.
MSeven - M17 on the App StoreWhat it is
M17 is an open-source digital voice/data protocol developed by and for amateur radio operators. Its voice path uses the open Codec 2 codec, and the project publishes specifications and software openly.
Where it fits at K6RCS
M17 is a natural K6RCS learning and experimentation layer: QSO One, gateways and hotspot software can make it accessible without turning the station into a museum of mode-specific radios.
Identity and addressing
| Callsign | Human-readable amateur identity rather than a vendor-issued numeric identity as the primary concept. |
|---|---|
| Reflector | Internet routing/conference target. |
| Module | Subdivision on a reflector where used. |
| Gateway/modem | Software/hardware layer between RF and the network. |
Setup order
- Start with the current M17 specification/docs, because the project is actively evolving.
- Choose the client/gateway path and prove local audio/modem operation.
- Connect to one reflector/module and verify callsign presentation and audio.
- Document the known-good software version and configuration before experimenting with bridges.
Common failure modes
- Using an old blog post as if it were the current specification.
- Bridging multiple systems before one native path is known-good.
- Forgetting that “open” does not mean “unchanging.”
Security and privacy
Do not publish passwords, API keys, device UIDs, hotspot security values, local IP addresses, management URLs, or detailed behavioral schedules. Keep backups of known-good codeplugs/configurations, use unique credentials, and document firmware/software versions before changing them.
Primary sources and directories
MDARC and the two-operator plan
MDARC currently reports its M17 RF service is awaiting a repeater software upgrade. Treat it as a restoration to watch, not available travel coverage. Check MDARC’s M17 status before planning an RF contact.
For Team Stone, retain M17-NCA module A and M17-PNW module A as app/PC test candidates. Verify the current reflector and module before use. MSeven - M17 is the current iOS client. It can work directly with M17 reflectors and, with compatible Mobilinkd TNC 3/4 hardware and a suitable 9600-baud KISS/discriminator radio path, can also put iOS on an RF M17 path. QSO One iOS remains a future commissioning item, not a tested deployment.
The FT-5DR is not a native M17 radio, and OS4P is not the M17 radio path in this stack. MSeven can provide networked M17 directly and can reach RF only through separately compatible TNC/radio hardware. Keep each operator’s own callsign and keep the path explicit.