Silsoesid, in short. There is no squelch on the aircraft I fly. So despite being one of those spiky haired iCadets everyone hates so much, yes I do know from a previous type how to use squelch, unfortunately I cannot. Yes I'm annoyed by it too.
Flying over France, where the boundaries are often miles apart, if VHF1 fails, then my only cue could perhaps be when the pleasant Paris controllers contact me on VHF2 Guard. So yes, I do have a general awareness of crossing FIRs and when I should expect a handover, but what about in between?