When cell phones fail
Posted: Thursday, August 02, 2007 7:08 PM by Alan Boyle
This week's tragic collapse of the Interstate 35W Bridge in Minneapolis triggered another collapse of sorts: a jam-up of the cellular phone networks in the area. Bystanders and survivors tried to phone loved ones, only to find that they couldn't put the call through. So what's the solution? Two words: text messaging.
For some cell-phone users on the scene, the call-blocking was brutal: "Every tenth call I tried to make went through, and half of the successful ones had problems like not hearing the other end, dropping, or unusable quality," Charlie Demerjian wrote in The Inquirer.
His bottom line was that "the cell network is barely adequate for public use, and completely inadequate for mission-critical use."
Cell-phone providers acknowledged that the call volumes overwhelmed their networks in the area around the bridge collapse, but they took issue with the idea that they're not up to dealing with a crisis.
"Whenever you have a crisis, people tend to use their phones a lot, and there is a tendency for networks to get congested," Mark Siegel, a spokesman for AT&T's wireless business, told me today. "It doesn't mean that there's anything wrong with the network."
Adding to the congestion was the fact that the collapse came at 6 p.m. CT, in the middle of rush hour, "during the busiest hour of the day for our wireless callers," said Karen Smith, a spokeswoman for Verizon Wireless in Minneapolis. Smith said the call volume came to twice as much as Verizon's system was built to handle.
AT&T's Siegel and T-Mobile spokesman Peter Dobrow told a similar story. Verizon and T-Mobile quickly brought in extra "cells on wheels" - cell-phone stations mounted on trucks - to handle the increased load. Siegel said AT&T started bringing in reinforcements as well, "but things had cleared up before they were moved into place."
The three company representatives were unanimous in their No. 1 piece of advice for cell-phone users:
"The biggest tip is to understand the importance of text messaging," Smith said. "Text messaging uses far fewer of our network resources."
Cell-phone networks are set up in such a way that text messages can piggyback on the streams of voice data traffic bouncing around the system. The digital messages, which amount to mere dozens or hundreds of bytes, can be slipped into the gaps in that stream.
"They're able to sneak through there, even when you and I are having a conversation," Smith explained.
So if you don't know how to use the text-messaging feature on your phone, now is a good time to learn. "Get one of your nieces or nephews to teach you how to do it," Smith joked, "or stop by a Verizon store and ask them to show you."
Here are two more common-sense tips for cell-phone use in a crisis:
- "Make your call as short as prudently possible, in order to help other people get on the voice network as soon as possible," T-Mobile's Dobrow said.
- "If you've dialed and you don't get through, wait at least 10 seconds," AT&T's Siegel said. "Don't just keep hitting the button again and again." Rapid redialing just adds to the congestion.
Even though the cell-phone jam has subsided at the site of the collapse, all three service providers said they were monitoring shifts in call traffic and positioning their resources accordingly. The aftermath of Hurricane Katrina taught the companies that reinforcements had to be pre-positioned for rapid response - and in the Twin Cities area, those reinforcements are being placed to accommodate higher traffic along the highways that are serving as alternates to Interstate 35W.
So what about the emergency communication systems used by first responders? The cell-phone jam didn't affect them, of course, and officials said the systems worked together without a hitch. Over the past three years, the whole state has been moving toward a 800 MHz system for emergency communications, said David Berrisford, field services branch director for Minnesota Homeland Security and Emergency Management. The first responders at the scene of the bridge collapse were literally all on the same wavelength.
"It worked wonderfully," Berrisford told me.
That view was seconded by Skip Jackson, Minnesota's section manager for ARRL, the nation's amateur-radio association. Ham-radio operators went on standby to assist in case they were needed, Jackson said, but "because the communications infrastructure of the emergency responders in the Twin Cities did not fail, there was no critical reason for us to deploy to the scene."
That doesn't mean the situation is perfect: For instance, if text messaging is the best way to get the word out from the scene of a disaster, doesn't it make sense that you should be able to text your cry for help to 911? Well, you can't do that yet - but just wait.
Next Generation 911 systems, capable of transmitting text as well as voice, data and video, are currently undergoing testing and could start rolling out next year. Police in Los Angeles are already looking into such a system. Boston police have begun accepting anonymous crime tips via texting, and New York is considering doing the same.
National standards for Internet-based 911 services could be released as early as next month, said Pete Eggimann, director of 911 services for the Twin Cities' Metropolitan Emergency Services Board. The board is already negotiating with potential vendors to conduct a pilot project, he told me.
"It's certainly being considered," he said. "That would allow us to pass along different forms of communication, as opposed to today's system, which just passes voice."
Eggimann said he'd like to have an Internet-based 911 system in place within the next year or two. Theoretically, such a system could take in not only text messages, but also video showing what the police might be up against at a crime scene, or data beamed automatically from vehicles involved in a bridge collapse.
"That's going to be the backbone," Eggimann said. "It will carry the next generation of 911."
