5900 KHz.......5-letter Morse code station.....0500-0530 UTC

And your question is?

http://www.arrl.org/band-plan-1

http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=26712

Technically - it cannot be Amateur Radio - since Amateur radio operators are not allowed to operate on 5900 / only 5100 - 5400 kc's and even then only on certain frequencies - channels if you prefer and not just anywhere you desire to turn the knob.

So then all you have to look at is what is authorized to operate on the 5900 Kc range - some type of government transmission, commercial radio?

By understanding the band plan - you can determine what countries you can talk to... Or which countries permit a certain frequency for use.

David,
Google "number stations." You can find them on several frequencies. Some have a female voice giving 5 number groups in Spanish and others send 5 number groups in Morse Code. Kinda neat cloak and dagger stuff. Hope this helps. Terry, k5teb