"No Signal" - A usable plot point?

Horror movies have always depended on the victims' being isolated from help, which is one problem that cellphones have been adopted to avoid. So what's the modern horror movie to do? Rely on "no signal" as a plot point - and here's a nice summary of a bajillion such plot points in various movies. With current cell coverage less than complete, this still works - as one character puts it, "97% national coverage and we find ourselves in that 3%." But in the near future it'll (hopefully) seem a lot less believable. Horror writers, start thinking up new plot devices!
[via Nerdist & Gizmodo]