Having done a lot of aircraft flight training in heavy jets and in different parts of the world, I have found the procedure to be the same for both circuits and upper air work.
A call to ATC to advise the aircraft's call sign, endurance and POB along with the area of intended training and planned duration is normally all that is required.
During the training detail should a need arise to revert to IFR, all that is required is an appropriate airways clearance.