D-STAR - Terminal Mode

In D-STAR communications, Terminal Mode is an operating mode that allows a transceiver (typically a compatible ICOM transceiver) to connect directly to the D-STAR network via the Internet, without using an RF repeater. It is useful, for example, when you are in a location with no D-STAR radio coverage but you have an internet connection (e.g., hotel, home, mobile tethering).

🧭 Terminal Mode – what it is in simple terms

It is as if your D-STAR radio became a "VoIP client": instead of transmitting over the air to a repeater, it communicates via the Internet directly with a D-STAR reflector or a gateway (using the D-STAR protocol, not SIP).

The Gateway must be of type ICOM G2/G3.

Due to costs, ICOM G2/G3 gateways have been replaced by MMDVM devices, so in Italy the possibility of connecting directly to the gateway is mostly absent.

📡 Main Network Requirements

To make Terminal Mode work, some network prerequisites are necessary, in particular:

Stable Internet connection

Any type: fiber, ADSL, 4G/5G, hotspot.

The port 40000/udp of your ICOM radio must be reachable from the outside. This means that (one of the two):

a) There are no other devices on your local network using UDP 40000 and you are using UPnP.

b) There are or are not other devices on the local network using UDP 40000, but the router does destination NAT to your ICOM radio.

Mobile connections are generally behind double NAT, meaning your modem/router is assigned a private IP address. With such connectivity, it is not possible to use Terminal Mode, unless you route the traffic via VPN to a server with a public IP that is capable of performing destination NAT to your ICOM device.

Ports used

The exact ports depend on the model, but for ICOM there are typically:

UDP 40000–50000 (for voice and signaling)

DNS and access to D-STAR servers

The device must be able to resolve DNS names and reach D-STAR G3 servers (in particular, Trust Servers, such as dstargateway.org).

An active D-STAR registration is required for your callsign, with terminal "Z" options correctly configured (in Italy they were all set up this way, so there's no need to worry).

Requirements

1. Compatible transceiver Typically ICOM ID-31A/ID-51/ID-4100/ID-5100/ID-52/IC-705 etc., with updated firmware. USB cable or integrated network interface (WiFi, Bluetooth, etc.)

2. D-STAR Registration You must be registered on a D-STAR gateway (e.g. on https://www.dstargateway.org) col tuo nominativo. In your callsign configuration, the "Z" terminals (e.g. Z, ZL, ZR) must be active for terminal mode.

3. ICOM Software or App Some devices use ICOM RS-MS3W (Windows) or RS-MS3A (Android) software to act as an interface. IC-705, ID-52, and ID-4100, for example, can also use Terminal Mode standalone via WiFi or Bluetooth.

Discussion & Support

Discussion and support channel. To discuss configurations or other topics, join us on fluxer.dreadful.work.