Representatives from major local phone companies and wireless carriers said early indications show little physical damage to their networks, but a crushing volume of phone calls has blocked hundreds of thousands of callers from connecting with family, friends and coworkers. Most of the major phone companies have requested that people refrain from flooding their networks with calls.
Despite the damage in New York and also in Washington, D.C., the nation's phone and Internet networks continued to operate and carry phone calls and data. As the phone networks became congested, many people turned to the Net for information--though intense traffic swamped many major news sites.
Few details of the Internet's health were readily available Tuesday; network traffic-monitoring firms such as Keynote Systems were scrambling to compile data.
"We don't know a lot yet. We're still trying to get details, but so far the Internet backbone isn't being affected," Keynote spokeswoman Mary Lindsay said. "There's no significant Internet infrastructure through the World Trade Center. It's primarily used for radio and TV broadcasting...However, there may be a lot of servers in there. But by and large, the real estate's too expensive there for housing many Internet and telecom servers...This doesn't mean there aren't regional access problems. And in fact, we know there are."
The Internet, originally designed decades ago as a military and educational network, was built in part as a way for communications to withstand nuclear attack by ensuring that messages could travel between points in the United States even if a major hub were destroyed.
This type of redundancy has been maintained as the Net has changed into a commercial network, even as engineers have spent more time focusing on routing around traffic jams and fiber-optic cable cuts than on potential nuclear devastation.
Regional networks affected
Nevertheless, the networks that carry data traffic are physical, not virtual, and redundancies have occasionally been strained to or beyond their limits. Simple accidents, such as a fiber cut or this year's Baltimore train wreck, can isolate a region or slow traffic going in and out of a local area.
Although the Internet's major coast-to-coast backbone connections appear to have been unscathed, regional phone and fiber-optic networks likely were affected.
Some local circuits on the Sprint network in New York, which supply phone and Internet connections to area businesses, ran under the World Trade Center and were damaged, according to the company. Sprint has routed calls to other circuits in order to keep the flow of calls going. Sprint spokeswoman Robin Carlson said that the volume of calls is "enormous" and that the company, too, is asking callers outside of both New York and Washington to limit calls to the area.
Sprint has also opened up all of its PCS stores in the New York area so people can make outgoing calls on the phones in these stores, she said.
Verizon Communications, the primary local phone company serving New York, Washington and much of the nation's Northeast region, reported no network damage.
Companies struggle to handle calls
By the afternoon, cell phone service was resuming in Manhattan and in Washington, D.C., according to reader e-mails from the area. Carriers however continued to warn users not to make unnecessary calls so lines could remain free for emergency calls.
Between 10 a.m. and 11 a.m. EDT in Washington, D.C., Cingular said there was a 400 percent increase in the number of people who dialed a number and hit a phone's "send" button. The rest of the Cingular network experienced a 200 to 250 percent increase in attempted calls.
Cingular also said a number of antennas that power phone networks was destroyed as a result of the explosion at the Pentagon. Sprint hardware was also damaged, the company said.
Security is also being heightened across many carriers' networks. Cingular, for example, has put its network on "high alert". The company did not comment further.
Representatives from Verizon said hundreds of calls were unable to connect. The company is redirecting base stations and other gear in other parts of the country to the New York City area to help deal with the crush of calls.
"Demand is outpacing our ability to handle all the calls," Verizon Wireless spokesman Jim Gerace said.
AT&T has asked for all callers not to call the New York City area. They are pleading with people to restrict their calls only to emergency purposes.
"There is an unbelievable volume of calls," AT&T spokesman Ritch Blasi said.
Similarly, an SBC Communications spokesman requested that people stay off cell phones as much as possible, particularly in New York and Washington, D.C.