Every so often while shortwave listening I’ll come across a frequency where tons of hams are talking all over each other giving a call sign and a six digit number only (not a QSO). I imagine these numbers may be club membership numbers but I can’t figure out the purpose. Is this some way to build up a large number of QSOs? Doesn’t seem like the requirements of a QSO are met by just getting a call sign and number. And how on earth does anyone copy all of these contacts given that everyone is pretty much talking over themselves, voices overlapping, with no moderator or any attempt to direct traffic?

What makes this even weirder is that I’ll sometimes hear other hams on the band who mention this but don’t know what it’s for either.

  • $\begingroup$ Can you provide some specific examples of the 6-digit "serial numbers" that you have heard? Are they somewhat sequential as a serial number would be, or do they seem to be related to (e.g.) a location or timestamp? Do the numbers used by one particular callsign change or is each ham using just one as an additional unique identifier? $\endgroup$ – natevw - AF7TB Aug 31 '20 at 17:36

What you're talking about sounds like activity that is common for a contest or a QSO party. If you're not familiar with QSO parties they are organized like contests, but the organizers try to emphasize everyone having fun, and don't focus quite as much on scores. There is a saying though, that if something smells, looks, and feels like an elephant then it's probably an elephant; in other words, QSO parties are generally regarded as contests, and are included in contest calendars.

Contests and QSO parties almost always include a signal report, which makes them bona-fide contacts in the eyes of most hams. However these days the signal report is almost always "59" for phone or "599" for Morse. Were the first two digits of the six-digit number "59"? Contesters like to leave a little pause between the signal report and the "exchange", but to outsiders, "five nine, one three seven six" might sound like a six-digit number. What's an exchange, you ask? It's a piece of data that the contest rules require to be exchanged. It might be the location of the station encoded in a numeric format, or a sequential serial number, or the year the operator was first licensed, or the name of the state or province the station is in, or just about anything else the contest organizers can dream up. For some contests the exchange changes every contact, but for others it's always the same for a particular station.

As for all talking at once, contests are competitive and operators will talk over each other in an attempt to get a contact with a rare multiplier. What's a multiplier? As an example, rules for a state's QSO party might define a contester's score as the number of contacts times the number of counties contacted (usually on a per-band basis). Typically there are rare multipliers, like a sparsely-populated county in the state's QSO party, that everyone is trying to contact. It's not uncommon for several stations to try to work the same station, usually a rare multiplier, at the same time, a situation known as a pileup. A skilled operator can pick individual call signs out of the cacophony and keep calling operators happy.

Here's a typical contest exchange ("W1ABC" and "VA3XYZ" were made up for this example, but may well exist as real call signs):

VA3XYZ: victor alpha three x-ray yankee zulu QRZ
W1ABC: whiskey one alpha bravo charlie
VA3XYZ: W1ABC, five-nine, one three seven six
W1ABC: thanks, five nine, four eight seven
VA3XYZ: seventy-three QRZ

So that was a valid QSO because signal reports were exchanged, although the reports were the standard 59s, and acknowledged with "thanks" and "seventy-three". VA3XYZ repeated the calling station's call sign; the calling station W1ABC didn't repeat VA3XYZ's, but implied that he or she did, because if he or she didn't copy the call sign then he or she would have requested a repeat (a "fill" in contest jargon). They were valid QSOs for this particular imaginary contest because the exchange included serial numbers, "1376" and "487".

Does that describe what you heard? If not, the next time you hear such activity, please make a note of details such as date, time, frequency, and transcriptions of a few QSOs, and we can probably help you out. Or write down a few call signs and email the operators to ask, and then come back here and answer your own question. (Many operators list their email addresses in qrz.com.)

  • $\begingroup$ Really nice answer, thank you. What I had been hearing were different voices, almost as if they were doing a roll call stating a station name and a number all one after each other. I think the best move for me is to get a recording of it happening again and then I'll update the question. Or maybe I was just mistaken as to what I was hearing. Thanks so much! $\endgroup$ – Jeremy Gilbert Sep 8 '20 at 17:09

Guessing it was a contest, and the numbers were the exchanges, per the contest rules.

The exchanges vary by contest, so it depends on which contest you heard.

Try searching the contest-calendar, here:


Perhaps with some more information we can narrow it down.

  • $\begingroup$ thanks for the suggestion @t252. I just check the contest calendar for the last few weeks and dug into all of the rule and didn't see anything that would seem to meet the description where everyone is on a single frequency. Don't most contests require proper QSOs with a CQ, response, acknowledgment, etc? $\endgroup$ – Jeremy Gilbert Aug 31 '20 at 0:15

If it was on the 10m band then it could have been the 10-10 club net.https://www.ten-ten.org/

  • 1
    $\begingroup$ Except it was 20m and 40m, not 10m $\endgroup$ – Scott Earle Sep 19 '20 at 15:50
  • $\begingroup$ Hello and welcome to ham.stackexchange.com! $\endgroup$ – rclocher3 Sep 21 '20 at 19:01

You may have stumbled onto a net that is specifically designed to allow amateurs to work on getting awards quickly by contacting others via net, such as the ARRL Worked All States (WAS) award. There's several nets that do this but perhaps the largest one is the OMISS (Old Man International Sideband Society) net. They hold several nets on several bands daily. OMISS has their own awards system also. More info at omiss.net.

Hope this helps.

73, Sean KS4TD


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