By Simon Mason
The author extends his thanks to
V. Nevdachin for the Lincolnshire Poacher lyrics
and to Dr. D. Lightowler for help with the word processor.
1991 by Tiare Publications
All rights reserved.
No part of this book may be reproduced or transmitted in any form or by any means electronic
or mechanical, including photocopying, recording or by information storage and
retrieval systems, without permission in writing from the publisher,
except for a reviewer who may quote brief passages in a review.

Layout and Design: Next Wave Graphics, Caledonia, NY
Published by Tiare Publications, P.O. Box 493, Lake Geneva, WI 53147, USA
ISBN: 0-936653-28-0

If you've ever ventured outside the shortwave broadcast and ham radio bands and tuned around the areas allotted to so-called "fixed" stations you may have heard voices reading out long lists of numbers in either four or five digit groups. These transmissions are generally called "numbers stations" and appear in a variety of languages. Transmissions in Spanish are heard most often in the United States but, in Europe, German, English and French, as well as a variety of Slavic languages are the most commonly heard.

What are they? Finding the answer to this question is not an easy task. For a start, none of these stations operates "legally". And, with two exceptions, no callsigns are used. Consulting frequency listings does no good either since the publications that do list such stations give their origins as "unknown". Relatively few people in the radio industry know about these stations, as this item from a recent issue of the British publication Shortwave Magazine shows: A letter from a Mr. B. Greater recalls the days in the early 1960's when Greater, then a teen, used to enjoy receiving and decoding weather reports. These transmissions are sent over shortwave in a format not unlike that used by the number stations. But he couldn't decode the data being sent in what he assumed were weather transmissions so he wrote to the meteorological office to ask where he was going wrong. The reply, from the senior signals officer, said the transmissions were German river soundings being transmitted in voice format from automated equipment! Other explanations suggested over the years include coded information for drug smugglers, lottery numbers, weather data, commodity prices and so on.

The most likely explanation is that these transmissions are coded messages sent to espionage agents. In various spy cases over the years agents have been caught in possession of certain items of "tradecraft". These have included shortwave radios, microdots , invisible ink and the so-called "one-time" pad. This pad consists of a number of pages of randomly generated four or five figure groups. The pages are made of a special material that can be easily destroyed by burning or perhaps even eating. As the name suggests, each piece of paper is used only once. When the station broadcasts it usually sends a numerical identifier to single out the page of the pad to be used for that particular message. When the message has been sent the recipient subtracts the number sent over the air from the corresponding number on the sheet (or vice-versa). This is the key to the pad's security. Without the particular sheet in question the message is unbreakable. Other methods of encryption could include the use of a book available to both sender and recipient, with a code to indicate individual words on a page. For example, "312 02" would denote the second word on page 312. It has been suggested that one particular station that has a 3/2 figure format may be using this system.

It has been noted that some stations send the same numbers up to a year apart -in one case even two years. This might suggest that practice traffic is being sent to agents for training purposes. Also, stations could be transmitting "disinformation" and time-wasting traffic to try and bog down the electronic eavesdropping efforts of an opposing intelligence service. Whatever the real explanation, a shroud of mystery surrounds these stations and only rarely is one allowed a glimpse into this shady world. One such occasion was during the trial of British spy Geoffrey Prime. It was revealed that Prime received his instructions via shortwave radio. His traffic was encoded in five figure groups and sent over the air in Morse code. This type of revelation is rare however and one can only guess at the full story behind these mysterious and fascinating broadcasts.

My own interest in number stations goes back some years. But it was only with the advent of shortwave receivers with digital frequency readout that I have been able to take an active interest in them. I decided to analyse these stations and perhaps figure out their purpose. This was no simple task since there were no frequency guides to refer to. It was a case of starting from square one. The first job was to separate the different types of stations and it soon became clear which stations were on a given frequency. Operating schedules were drawn up and it was exciting to hear a station pop up at the predicted time. Of course their locations, purpose and the meaning of the messages were practically impossible to deduce from merely listing times and frequencies. But this, at least, was a start and better than nothing.

Part One


I began with a station I had first heard in 1971. It was a German station using a female voice machine. It is easy to tell if a machine is being used as all the numbers are spoken with an identical delivery. This female German numbers station had a rigid schedule and format. It also used a musical marker or interval signal - a four note tune rising up the scale: "so-la-te-do" played on some sort of electronic organ. This tune was aired for a five minute period before the hour. On the hour the woman would send the headings of each message to follow, for example:

34324/05 67545/07 55433/11 34534/15
11244/18 53466/21 32124/26 12334/29
15566/33 12456/38 98676/41 75555/47

The stroke symbol (/) was spoken as the word trennung. These headings were sent for exactly five minutes. As you can see, the two figure number after the first trennung symbol is "05", which indicates when message number 34323 is due to start.

At five minutes past the hour there was a pause and the woman said "achtung" and then the first heading was sent again but this time the "05,, was replaced by the number of five figure groups in the message. For example, 34324/22 meant that 22 five figure groups were in message 34324.
"Achtung34324/22. Achtung34324/22 11223 24566 55454 46578 25555 33367 57567 45585 34665 66477 58577 54888 01123 63645 58999 10122 46547

After this, "achtung" was sent again, followed by the heading for the second message -67545/39, for example. As can be seen, the final message has a suffix "/47, which means that this message starts at 47 minutes past the hour. Presumably the recipient would listen to all of the headings in the first five minutes and then not need to listen again until the time his message was due to begin if, indeed, a message was intended for that recipient on that night. After the last message the word "ende" was sent and the station fell silent until five minutes before the next hour when the sinister-sounding electronic tones were sent again, heralding a new set of headings and messages.

3217 kHz at 1800, 1900, 2000, 2100
3820 kHz at 2000, 2100, 2100, 2200

During the summer months in Britain the station kept to British Summer Time, i.e. UTC plus one hour.
The same messages sent on 3217 were re-broadcast two hours later on 3280 so if the first airing was missed there was still an opportunity to hear it. This was one of the very few numbers stations that changed its schedule when daylight savings was in effect. Most kept to the same UTC time so here was a tiny clue that the messages and the station were genuine. One could imagine that the agents involved would have a set monitoring routine somewhere in West German society and the schedule would be ordered so as to produce the least inconvenience to their routine. The same station also appeared during the day using the same format but with perhaps only half as much traffic as in the evening.

This was the normal daytime schedule:

5820 - 1000, 1100, 1200
6450-0800, 0900, 1000

(UTC times in winter, British Summer time in summer)

There was apparently no connection between the traffic on the two frequencies. Only on three occasions did I note any additional broadcasts: once on 3820 the woman was heard with some kind of test transmission at 0500 but the signal kept switching on and off in the middle of the transmission, making it impossible to copy the full text. On another occasion the station was on 7625 at 2000 and 2100. The last unusual transmission was heard on 7430 at 2100. These were apparently "one-off' broadcasts and were not repeated.

The great changes taking place in East Germany as the 1980's neared an end also changed the output from this station. Gradually the traffic lessened to a point where perhaps only two transmissions per night were heard - sometimes none at all. In the last days of this station the schedule became even more erratic and eventually fell to only once per week. Then, towards the end of April, 1990, the station vanished. It made me wonder if perhaps the whole shadowy world of numbers broadcasts was about to end, along with the careers of all those thousands of former East German agents. It certainly seemed so when another numbers station disappeared.

This station had a very distinctive interval signal (musical marker) and it is difficult to describe the eerie feeling one got when hearing it. People who live near the sea know the sound of bells used to warn ships of foggy conditions. This interval signal sounded like a lightship bell recorded on tape, except that the tape sped up or slowed down which made the bell sound very distorted. The tune was of eight notes, the first four descending down the scale, the last four rising, as: Fa - Me - Ray - Do - Ray - Me Fa - So." With all of the dynamic "wow" on the tape the whole thing sounded very strange. The female voice machine used was also unique.

       Continued on Page 33