This question will be regarding airlines, flying high altitudes.
As with short flights, you are in contact with local controllers, then get passed off to enroute and local again.
I am familiar with SELCAL, where you do not have to listen to HF Radio jumble for your 7 hour oceanic flight.
However, what if you are flying for example Dublin to Hong Kong, not crossing oceans. Will you be in contact with ATC the whole time, and the pilots on duty always having to wear headsets just in case if ATC wants to find them? Or would there be a system similar to SELCAL where they will buzz the aircraft only when they need them?