The aircraft I flew for my first job after high school had no aircraft radios; we used CB radios. Ag airplanes, we didn't have much use for aircraft radios. Each airplane had a CB radio to call the company, or each other, but those weren't used much, either. Later, 10 codes were something we used for police radio, and I had a habit of reverting to aircraft radio language (phonetic alphabet, etc). I still say 10-4, once in a while. Not internationally, though. Or intentionally.