Both in last week’s Boston bombings and last weekend’s earthquake in China’s Sichuan province, mobile-phone networks were quickly overwhelmed as people rushed to call family and friends. In both cases, users took to services that use bandwidth more efficiently, like text messaging, microblogging and instant-messaging apps.
Voice calls consume about eight times as much bandwidth as text messages. Moreover, they must pass through the network in real time. Text messages, on the other hand, are slivers of data that use relatively little bandwidth, and line up until a break in the network traffic lets them slip through. The same is true of microblogging services such as Twitter, Sina Weibo and Tencent Weibo, and instant messaging apps like WhatsApp or Tencent’s WeChat.
So it’s no surprise that, as the dust settled at the finish line of the marathon in Boston, carriers asked subscribers to avoid making calls and use text messages instead. Some used Twitter, to broadcast to a wider range of people.