You never know who's listening....
The little aircraft company I worked for had a couple of company HF frequencies - the monthly radio check required me to check the HF system but it was late at night and all our offices had gone home. I called Auckland on 8867 and 5643 - nothing. Tried Brisbane on the same and no replies - suddenly a voice piped up "This is the USS something - you are loud and clear - how me and whats your location?" I went back with a "loud and clear also, I am in Christchurch, New Zealand, where are you?" He "Aw, we're out here bobbin' around on the wide blue nowhere...."