communicating with other aircraft during flight
This incident happened when I was on the flightdeck for a short visit (in the good old days when visits were allowed). Anyway, we were at FL 340 and there was another aircraft at FL 390. The First Officer was trying to contact ATC but had the frequency wrong and the Capt. Suggested that he just ask the aircraft above - which they did.
Is there a specific frequency that one can use to communicate with other aircraft in the area. Or is it just the common frequency for the area - which all others are using at the time.
(Sorry if the question is a little vague).