Non-airliner-pilot sticking his head in here, so I hope I'm not completely wrong. However, I don't believe 123.45 is an official international air-to-air frequency. In fact, I'm told that it's actually allocated for use by some UK airfields, and that pilots flying around the UK using this frequency for air-to-air can cause problems. (Sorry, don't know which airfields - can anyone confirm this with details of actual airfields?)
Having said that, it is allocated as an air-to-air frequency in some airspace, such as the North Atlantic, and it does seem to be widely (and illegally) used even where it's not specifically allocated as such.
FFF
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