Initial reports after the Boston Marathon bombs went off suggested cellphone networks had been shut off to prevent possible remote detonation of any others.
Carriers said the explanation for the lack of service was actually simpler: The lines were busy.
Cellphones are least likely to work when we need them most because everyone needs them at the same time, and cell towers can only handle so much at once.
Many cell sites are designed to handle “150 to 200 calls per second per sector,” BloombergBusinessweek says.
But they’re not evenly distributed, and some can accommodate more connections than others, according to a Boing Boing post that gets into the technical nitty-gritty. It depends on location and your phone network, and there’s no practical way to learn those details during an emergency.
That doesn’t mean your phone is useless. Text messages are a much better option than calls, because they take up less of a cell site’s resources and because if they can’t get through, they automatically keep trying. If you are connected to the Internet or can find nearby free Wi-Fi, email and Twitter are also quicker, more reliable options.
Here’s something else to do to prepare for emergencies: set up an emergency contact on your phone so first responders know who to call if something happens to you.