As many people have noticed, the number "9" is rarely (if ever) heard in the V2a Cuban voice numbers broadcasts. If the encryption is random, it seems odd that there wouldn't be any 9s. Why would this figure be excluded? Why is it present in filenames/headers for SK01 (the digital file transfers)?
One more mystery wrapped in a riddle shrouded in an enigma, no pun intended. (After all the German ENIGMA code had 9s.)