But this situation would at least hold the possibility of a compromise solution in which the "tower" is only turned on for, say, 30 minutes out of every 4 hours, or turned off during sleeping periods, or . . .
Although if the airline is deriving revenue from the tower through a surcharge on calls made through it, as seems likely, even that is probably too much to hope for.
How about a couple of "phone-booth" seats back by the lavatories, with a per-minute use charge? (which could in fact be collected automatically by a surcharge that's not paid on the spot, but goes on the caller or callee's phone bill for the call)