P25 is the public-safety heavyweight, and on the amateur bands it reaches across the internet through reflectors much like the other modes. But P25 has a slightly tangled online history — two separate networks grew up side by side — so understanding P25 reflectors means understanding both. This is a plain-language explanation of what a P25 reflector is, how your radio connects, and the two worlds a P25 signal can travel in.
A P25 reflector is a server that acts as a central meeting point for P25 radios. Hotspots and repeaters connect over the internet, and everyone connected hears everyone else. Like the NXDN reflector, it’s a single-mode, deliberately simple thing — P25 and nothing else. The most common software comes from Jonathan Naylor’s P25Clients package (and the DVReflectors fork), free and open under the GPL, and it usually ships with a parrot — an echo-test server that plays your audio back so you can check your setup.
As with NXDN, a P25 reflector is a single talkgroup, identified by a number — not a building of lettered modules like XLX or URF. The reflector is the room. To change conversations, you connect to a different reflector rather than switching modules within one.
Your handheld reaches a repeater or hotspot over RF as usual, and a companion program called P25Gateway handles the internet link. The gateway finds reachable reflectors by reading a shared P25Hosts.txt list; the default connection port is 41000. Keying a reflector’s talkgroup number from your radio tells the gateway which one to join, and the link drops again after a spell of inactivity.
Public and private reflectors
A private P25 reflector — for a small group of friends, say — only needs its details in a local hosts file on each participating device. A public one gets a reflector number and address added to the shared list so anyone can find it; those numbers are coordinated so two reflectors don’t collide on the same one.
Here is the wrinkle unique to P25. Two linking systems grew up in parallel:
P25Clients, the kind most hams reach through Pi-Star or WPSD.The two were never fully merged — by deliberate choice, the mainstream P25Hosts list doesn’t cross-link into P25NX — so a newcomer will find the MMDVM reflector world is the one they connect to from a hotspot, while P25NX remains its own, more repeater-centric realm.
P25 uses the IMBE vocoder — a codec all its own, shared with none of the other modes. That means bridging a P25 reflector to DMR, YSF, NXDN, D-Star, or M17 always requires transcoding. The good news, as covered in Understanding URF Reflectors, is that P25’s IMBE can be transcoded in software — so a multimode reflector can fold P25 in without extra vocoder hardware, unlike the AMBE-based modes.
A P25 reflector runs happily on a small VPS. You compile the reflector software, choose a talkgroup number, and set it up as public or private — adding it to the shared hosts list if you want it found, or keeping it in a local list if you don’t. Many operators run the parrot alongside it, so newcomers have an easy way to test that their P25 gear is working before calling on a live reflector.
The mainstream P25 reflector software comes from Jonathan Naylor, G4KLX, whose P25Clients repository provides the gateway, reflector, and parrot under the GPL — the same lineage behind his NXDN, D-Star, and YSF tools. A widely used fork lives in nostar’s (Doug McLain, AD8DP) DVReflectors, which packages the P25, NXDN, and YSF reflectors together. P25NX is a separate, earlier project aimed at linking commercial Quantar repeaters over IP, and it continues to run in its own right. Between them, they gave amateur P25 a way onto the internet — all of it open and run free of charge for the community.
A noncommercial hobby reference compiled by N6JET, gathered from public sources and shared freely for anyone interested in amateur digital voice.