Why didn't the controller try to call them up on guard frequency? Don't most commercial aircraft have one radio dedicated to listen in on 121.5? And the controller probably have a touch key on his screen to enable him to transmit on guard easily.
Not in any tower that I have worked in, or know of! The best we have is a hand held that has to be switched on, changed to 121.5 cos it’s probably set to TWR or Ground freq. We’ll try comm checks on TWR, check with APP if the acft is with them, maybe get Ground to broadcast, and show the signal lamp