Connect to APRS-IS

APRS-IS is the internet backbone of APRS — the worldwide network that igates feed and sites like aprs.fi read from. Connecting the app to it needs no radio and no hardware at all, and it is the fastest way to see live traffic on the map. You can run it on its own, or alongside a radio.

The channel is already there

A fresh install comes with an APRS-IS channel in the Channels section of the Radio screen (under More on the tab bar), switched on. It connects the moment the app has a callsign to log in with — a channel without one shows "Set your callsign first" — and needs nothing else: no account, no registration, and no passcode to look up.

If you have removed it, tap Add channel and choose APRS-IS — "the internet backbone. No radio required."

Servers: the app picks your region

APRS-IS Tier 2 servers are organised into five regional pools, and aprs2.net asks clients to use the pool for their own region rather than the worldwide one. The channel editor offers the five as one-tap presets — North America, South America, Europe & Africa, Asia, and Oceania — plus a CUSTOM option for a club server or a specific host you type yourself.

A server on another continent works, but it delays everything — including the echo of your own beacons coming back, which can make your own station look like a second one. Stay regional unless you have a reason not to. Port 14580 is the filtered-feed port and the default.

The passcode is derived — you never type one

APRS-IS logins use a passcode computed from the callsign. The app derives yours automatically, so there is nothing to generate on a website and nothing to paste in. If your callsign is set, the login just works.

The receive filter

APRS-IS carries the whole world's traffic; the filter is what tells the server which slice to send you. The app builds one automatically — traffic within 150 km of you plus anything to or from your callsign. Hearing your own traffic is deliberate: it is what lets the app show the Digipeated delivery state and pick up incoming acks.

The filter is always shown on the channel, and it is editable. Open APRS-IS filter from the More menu (or tap EDIT FILTER on the channel) to change it:

• Builder mode covers the common cases with plain controls: My traffic (anything to or from your callsign, any SSID), Nearby traffic (around you, around a fixed point, or none), Watch callsigns (comma separated, wildcards allowed — N0CALL* covers every SSID, heard no matter how far away), and Callsign prefixes (a club or a country — note that a short prefix like KO4 matches a large number of stations).
• Advanced mode edits the exact filter string sent to the server on login, with an on-screen reference for the term syntax. Terms are OR-ed together — every term admits traffic on its own — and the app warns before you apply a filter that would admit worldwide traffic.

APPLY reconnects APRS-IS with the new filter; RESET TO AUTOMATIC puts the derived default back.

Receive-only: listen without transmitting

Each APRS-IS channel has a Transmit to APRS-IS switch. With it off, the channel is genuinely receive-only: the app logs in read-only, and anything routed to the channel is refused, not dropped quietly — you get an error instead of a beacon that silently went nowhere. This matters because a server accepts and discards traffic from an unverified login without reporting it.

Receive-only mode is also how you listen without a licence. Transmitting on APRS requires an amateur radio licence; receiving APRS-IS traffic does not, and a receive-only connection is a fine way to watch how APRS works before you are licensed. See Getting started for the rest of the first-run picture.

Running APRS-IS alongside a radio

Channels are independent, and any combination can be connected at once — an APRS-IS channel next to a Bluetooth KISS TNC, a USB TNC, a network TNC running Direwolf, or an audio-cable modem. Each beacon chooses its own routing: everywhere, or only the channels you name — so you can beacon on RF only while still receiving over the internet. Messages go out over every connected link. Connect a radio is the starting point for the RF side.

Knowing it is connected

The Radio screen shows each channel's state, and RECONNECT ALL restarts every link at once. On the messaging screens, RF and internet status appear as two separate indicators, with connected and connecting visually distinct — so you always know which path your traffic has. When a message or beacon travels over the internet rather than the air, the app says so plainly in the delivery detail and the packet log.

Next steps

• Send your first beacon — put yourself on the map.
• Connect a radio — add the RF side.
• Messaging — threads, delivery states, and retries.

Last updated 31 August 2026