I know that it's a few years ago but the ORR's Periodic Review for Control Period 5 (PR13, for 2014-19) included £75,000,000 of funding from the Westminster and Scottish governments for level crossing safety and there was an expectation that 500 would be eliminated during the Control Period.
(This is just to give a bit of background. Obviously the 500 closures would tend to be the cheapest/easiest/quickest to deal with and not directly related to the OP's point about the challenges of telephone communication. Some of the money would go on upgrades to crossings being retained rather than full closures.)