Station OLX was one of the very few stations that used a ITU registered callsign. Here is a description from Langley Pierce's book:

The second station operated by the Czech Intelligence Service (now operated by the Czech Republic) ventures into the use of ITU allocated callsigns.

Transmission Format-- Five minutes prior to transmission on the hour, this station sends in Morse code the callsign OLX in the form " VVV DE OLX OLX." Interestingly enough OLX is allocated to CETEKA, the Czech Press Agency! A three digit message identifier is repeated for five minutes beginning on the hour or half hour. This number is used to indicate whether or not the broadcast will carry traffic. if not, then the transmission ends after two minutes. In the below, 73 represents the group count.

Preamble: 424 424 424 424 424.�

Message: 73 57966 85288 30427 74322.... Papaqui 73 57966 85288 30427 74322 .... Conet.

Broadcasts, which begin on the hour or half hour, are presented in non-standard Czech by a computer synthesised female voice at 10 groups per minute. Note the nonstandard pronunciation, in particular of "yedna", which in standard Czech is pronounced as "yeden." This is believed to be a Czech military pronunciation.

1. yedna  6. shest       Papaqui - Repeat
2. dva      7. fedum      Conet - End
3. shi      8. ossum
4. shtiri   9. deviet
5. pyet   0. Nolla