Electromagnetic wave is like light, travelling at speed of light at the medium. Usually you have more than 1 cell tower able to reach your signal and they can calculate your location based on timing. Pretty much how GPS work as your GPS device or phone receives usually at least 3 (I heard typically 6+) satellite time signal and then its algorithm figure out your location by that time differences.Still not sure exactly what you mean. Perhaps you are laboring under the mistaken idea that everyone has an active cellular telephone on their person at all times, or a car that communicates with the outside world.
A lot of phone got updated when the E911 mandate went in effect, basically at that time all phones would require GPS signals and use that to feed into a 911 call because if not a landline you need to know the location in an emergency if you passed out during a call.