In the city, a writer has to stand on her head to get around the problem of cellphone coverage, public wifi (and old Starbucks or Tim Hortons will do), and Google map functions that can tell you the location of any place you want and how to get there. It's really hard to be lost or out of touch in the city. It used to be that there were enough dead zones in rural areas that a writer could get away with having no signal for their hapless hero to use. This still happens, but it's increasingly rare. Add to that the availability of satellite phones, and the excuse of no signal becomes tenuous. What halfway competent, forward-thinking hero would head into the wilderness without a satellite phone, beacon locators, or at least a hand-held GPS?
The problems really started with the advent of 911 (or possibly with telephones themselves) but has steadily worsened. We have all read books where the hero gets herself into a ridiculously complicated situation while the reader is silently thinking "Oh for Pete's sake, why doesn't she just call 911?" Modern readers are savvy, and you can bet some of them know the latest tech gizmos that every intrepid hero should not leave home without.
Cellphones and other devices can be used to advantage for the writer too, of course. A cellphone can be found by the dead body, and its history and messages can provide clues. Cellphone conversations can be choppy or incomplete, the signal fading at the crucial moment when the killer's name is being mentioned. Computer search histories and emails are a gold mine of information to enhance the mystery. We writers have embraced that. Now if we could just lose that pesky smartphone when we need to. Anyone out there have any other ideas?