Earlier this year when East Timor was crippled by political unrest, the country's foreign minister, Jose Ramos-Horta, reportedly notified the prime minister of his intention to resign in protest via text message -- because short message service (SMS) had become one of the country's most reliable ways to communicate.
SMS, designed to send text messages of 160 characters or less, is proving to be a valuable tool in the emergency communications arsenal in times of crisis. During Hurricane Katrina, for example, SMS was one of the only methods of communication.
"What's interesting is less and less people use SMS, but it's a very effective tool," said Matt Foosaner, director of Sprint's Emergency Response Team.
"Everybody wants that instant voice communication, and now we want data communications with almost streaming video capability, but SMS is like one of those tried-and-true tools in your toolbox," he said. "It's the wrench that isn't quite as slick looking, but when you need it, it typically works very effectively for what it is."
Keeping It Simple
Text messages are less vulnerable to the network congestion that accompanies most disaster situations for several reasons, Foosaner explained. First, they are much smaller. "The amount of ones and zeroes required for a text message is substantially less than a voice message," he said.
They are also less complex. While a text message makes its way across the network as one little packet of electronic data, voice data requires the network to break a continuous stream of data down into packets, and reassemble it to produce a continuous audible stream at the other end.
"Sometimes if everyone is trying to call into the network, the cell phones are impacted or the publicly switched telephone network is getting congested, you know sending one bursted message, even if it's a two-way message, coming back is a lot easier on the network than trying to sit there and hold a conversation, and drive and pass from one cell site to another because it's just done," Foosaner said. "It's instantaneous. It's one message out."
Another factor is that text messages do not take the same signal path that voice calls take, said Cosmas Zavazava, who is the head of Least Developed Countries, Small Island Developing States and Emergency Telecommunications for the International Telecommunication Union, as well as the union's focal point for emergency telecommunications. Messages sent via SMS are sent through an SMS center, rather than point-to-point. This store-and-forward method ensures that messages are received whether the recipient's device is on the network or not; so should a user turn his or her phone off, he or she will still receive the text message when the phone is turned back on.
SMS also has drawbacks -- it doesn't operate in real time, so messages may be delayed for hours, or dropped altogether -- when communications networks become overwhelmed.
"Congestion is a lesser problem than in the voice traffic channel. Users are not subject to the same traffic congestion patterns encountered by other communication methods, like voice, and users can send messages at almost any time," Zavazava said. "However, other network characteristics like signal latency can impede the progress of SMS messages.
"SMS is neither instant nor real-time," Zavazava continued. "The messages can arrive within a few seconds of being sent, or they can be delayed for hours due to network congestion. But as I said, because the messages are normally short, this is unlikely unless it's a major disaster, and everybody's trying to send messages at the same time."
Using a queuing method rather than point-to-point means messages may cause delays, but denial of service is much less likely than with voice, where if there is no opening to carry the data, the call is immediately dropped.