our old record player had the radio station call-signs for all of Australia displayed on the console. There were a few random 9xx ones scattered around, probably including the ones listed above. I also seem to recall some other randoms like “1YA, 2YA, 3YA”… on the display. Maybe were these New Zealand call-signs or something?
EDIT: Yes, it seems that’s exactly what they were Radio in New Zealand - Wikipedia
there used to be a comedy series on ABC Radio National, I think it was called Don’t Get Off Your Bike, but it was based around a fictional radio station called 10KU Kalangadoo. Apparently they used to score interviews with some prominent people thinking it was a legitimate radio station and completely being oblivious to “10” not being a valid radio call-sign.