Message delivery

Every message the OTA bot sends carries a small chip on the op page and the QSO page: PENDING, CLAIMED, SENT, ACK, EXPIRED, or ABANDONED. The chip follows that one message out of OTA and across the APRS network. It says what happened to the message. It never changes what the message means for the game.

How a message leaves OTA

1. The outbox. When OTA has something to say, it writes the message to its outbox. Nothing has been transmitted yet.
2. The gateway. A separate program, the gateway, is logged in to APRS-IS as OTA. Every few seconds it asks the outbox what is waiting and claims it.
3. APRS-IS. The gateway hands the message to aprsd, which gives it an APRS message number and transmits it on APRS-IS, the internet backbone of APRS.
4. RF. An iGate that has recently heard the recipient on the air puts the message on RF. An app connected straight to APRS-IS receives it over the internet instead.
5. The ack. The recipient’s radio or app answers automatically with an ack carrying the same message number. The ack travels back the way the message came.
6. Retries. If no ack arrives, aprsd transmits the message again. It sends three times in all, waiting at least 62 seconds after the first and 93 after the second, then gives up.

The chips

ACK and EXPIRED are final. ABANDONED almost always is, since only a late report from the gateway can replace it. The others normally last seconds, so on a finished op you will see almost nothing else.

PENDING

A message is pending for a second or two after OTA writes it, until the gateway’s next poll. A message that stays pending means the gateway is not polling, usually during maintenance or an outage. Pending messages are not thrown away. They all go out when the gateway comes back, oldest first.

CLAIMED

The gateway has the message. It normally reports SENT within a fraction of a second, so you will rarely see this chip.

A claim is a lease. If the gateway takes a message and never reports back, because it crashed in the middle of sending for example, the claim lapses after three minutes and the message is offered again. Nothing is lost that way, but the message may be transmitted twice. OTA offers a message three times at most. See ABANDONED below. A retransmission gets a new message number, so your radio cannot recognize it as a duplicate and may show it twice.

SENT

aprsd has transmitted the message on APRS-IS and is waiting for an ack. SENT says the message left OTA. It does not say the message reached RF or reached your radio. Within about three minutes it becomes ACK or EXPIRED.

A message that stays SENT for good has lost its tracking. The gateway keeps the link between an outbox message and its APRS message number in memory, so if the gateway restarts while it is waiting for an ack, nothing will report on that message again. It is rare, a handful of messages in a hundred thousand.

ACK

The recipient’s station acknowledged the message. Most acks answer the first transmission. In September 2026 the median was 1.3 seconds, and 9 in 10 arrived within 25 seconds. An ack that arrives a minute or more after SENT is answering a retry.

An ack is sent by your radio or app, not by you. It confirms that your station received the packet. It does not confirm that anybody read it.

EXPIRED

aprsd sent the message three times and never heard an ack. That takes about 160 seconds from the first transmission. About one message in five ends this way.

EXPIRED does not prove you never got the message. APRS is a two-way path, and the ack can be lost on the way back just as easily as the message on the way out. A common case is a radio that hears the iGate clearly while the iGate cannot hear the radio’s ack. When the message really did not arrive, the usual causes are:

• No iGate has heard you recently. An iGate only transmits to a station it has heard on RF in the last half hour or so. Beacon at least every 15 minutes while you are playing, as Host an op explains.
• You are out of range, or your radio is off or tuned elsewhere.
• Your app does not send acks. Most do. A few APRS-IS clients and some radio configurations do not.

ABANDONED

OTA gave up retrying. The gateway was handed the message three times, and each time its lease lapsed with no report of what happened to it. Rather than put it on the air every three minutes forever, OTA stopped offering it.

ABANDONED says what OTA did, not what happened on the air. The gateway reports SENT the moment it passes a message to aprsd, so a message only reaches this state when those reports failed three times running. It was most likely transmitted, perhaps more than once, and you may well have received it. That is why the chip is grey rather than red.

If the gateway’s report does arrive later, it replaces ABANDONED with what really happened. You should almost never see this chip. It exists so a fault between the gateway and the website costs a couple of duplicate messages at most, instead of an endless stream of them.

Delivery is not the game

A chip describes transport. Game state never waits on it. A QSO whose DE relay expired is still waiting for the host’s QSL, and the host can still send it. A QSO whose QSL relay expired still counts and still scores. The chip is there so you can see what the network did, and so a missing message has an explanation.