It is now feared that hotels will start installing mobile jammers so
that guests will revert to using the landline phones and thus
re-establish those now lost revenus.

I imagine this won't last much past the time the third or fourth
person checks out early and advises the hotel that in the future he'll
be staying at a hotel that acts like it wants his business.

Hotel chains seem to have a death wish about theit phones. If they
priced phone calls in a reasonable ballpark, e.g., 25 or 50 cents for
a local call an under 10 cpm for long distance, people would actually
use it, and they'd make tons of money. I once asked a hotel financial
manager about this, and he just rolled his eyes and sighed.