The MMDVM page on this site ends with a stack: radio, modem, MMDVMHost, gateways, internet. For most modes, the gateway layer is simple — a YSF gateway connects to one YSF reflector, an NXDN gateway to one NXDN reflector, and that's that. DMR is different, because DMR's world is different: not one network but many — and you shouldn't have to choose. DMRGateway is the program that lets you stop choosing.
MMDVMHost, on its own, can hold exactly one DMR network connection. Point it at one server and that's your whole DMR universe until you log into the dashboard and change it. But the DMR landscape is a dozen networks, each with its own talkgroups, friends, and nets. Without help, every hop between networks is a configuration change.
DMRGateway slides into the stack between MMDVMHost and the internet. To MMDVMHost, it looks like a single, ordinary DMR network — nothing changes on that side. But on the internet side, DMRGateway opens several network connections at once, each a full, legitimate login to a different DMR network, each with its own identity (your DMR ID plus a distinct two-digit ESSID suffix, so the networks can tell your connections apart). One physical hotspot, several simultaneous network presences.
The routing is rule-based, and the rules key off the talkgroup number you transmit. Each network slot in DMRGateway owns a set of talkgroup ranges — these TGs belong to network one, those to network two. Key up TG 91 and DMRGateway hands your transmission to the network whose rules claim 91; key up a talkgroup claimed by another slot and you've changed networks without touching a dashboard. Where two networks both use the same number, the common solution is a prefix: dial the talkgroup with an agreed leading digit or two, and DMRGateway strips the prefix and forwards the bare talkgroup to the right network. Your radio's channel list becomes the network selector.
Traffic coming the other way is simpler still: whatever arrives from any connected network flows back through MMDVMHost to your radio, with the gateway keeping the streams straight so two networks don't talk over each other.
The everyday win is convenience — your morning net on one network and your friends' talkgroup on another, both one key-press away, no reconfiguration. But the same machinery scales to the extreme: a single hotspot can hold half a dozen or more simultaneous network logins, making one small box on a shelf a citizen of essentially the whole DMR world at once. And because DMRGateway also accepts connections from things like XLX reflectors in their DMR guise, it's quietly the glue in a lot of cross-mode setups too.
The big idea
The talkgroup number was always how DMR users chose who to talk to. DMRGateway extends it to choose where — turning one radio, one hotspot, and one antenna into a doorway with every network behind it.
A noncommercial hobby reference compiled by N6JET, gathered from public sources and shared freely for anyone interested in amateur digital voice.