Over mainland no a/c will be using HF and that is where the Selcall will normally operate. Although Selcall is a function that is available on VHF I am not aware of many a/c or airlines that use it and 99% of crews would not know what was going 'ding'!!
I believe there have been a few airlines that use VHF Selcall but to have it as a 'system' as you suggest would require enforcement.