Paging lost pilots on guard
Just curious, do you controllers have access to the data in field 18 of the filed flight plan of a flight?
If yes, why is SELCAL no option to page those not responding to voice calls? Very most medium and heavy airliners and many bizjets are SELCAL equipped, and most dispatch solutions file it's code in field 18, like SEL/AB-CB.
And before you say your station isn't SELCAL equipped, such encoders are nowadays available even on your smart phone.
Voice calls can be overheard, but the SELCAL going off will alert anyone.