Where circuit-switched networks failed, IP pipes saved the day - at least for companies that knew how to use them.
The diverse routing features of voice-over IP helped loved ones get through to Manhattan in the hours after the World Trade Center towers collapsed when wireless and circuit-switched calls rang fast busy. But it may be years before expensive packet-switched networks replace bought-and-paid-for legacy systems, in part because the industry cant agree on a VoIP switching standard, analysts say.
"This event really showed the value of the Internet; it lived up to its hype," said Stacey Reineccius, president of Quicknet, which runs VoIP call services for businesses.
Though VoIP is typically sold as a part of a proprietary small- to medium-business telephony package, millions of calls outside the office setting ride on IP networks without customers knowing it.
ITXC, a wholesaler of voice connectivity over IP pipes, saw call volume jump 30 percent on Tuesday. But the company still managed to deliver toll-quality calling to the large telecoms that contract for voice minutes.
"If we werent giving quality that was as good as the regular public switched telephone network, then the major carriers and regional Bells that use us wouldnt be using us now," said Tom Evslin, the former AT&T WorldNet president who now heads ITXC. "Since they are not telling their customers that calls are going over the Internet, we have to deliver a quality thats comparable with what their customers expect."
ITXC used every trick in its playbook to complete calls, delivering them via different routes and shifting carriers, which points to the IP networks potential for taking over transport of both voice and data.
One carrier lost its Manhattan call center Tuesday, but service was not interrupted because calls were rerouted through New Jersey and Texas, Quicknets Reineccius said.
Within about five hours, engineers working in Israel were able to get the New York center running again, setting up Internet-based control servers elsewhere in the world, he said. "Its a huge endorsement of the Internet and IP. In a traditional environment, you wouldnt be able to do that," Reineccius said.
Circuit-switched networks, during a disaster will collapse, said Larry Roberts, one of the architects of Internet precursor ARPAnet. "They cant handle loads. The calling rate destroys their network."
But modern IP switches can be loaded to the limit "and keep on working better and better to the 100 percent load limit," he said. Then they slow.
Still, some analysts doubt that a packet-switched world would have helped ease traffic congestion Tuesday - simply because no network is built to handle once-in-a-generation events that send millions to the Internet and their phones.
They say circuit-switches and wireless phones didnt perform poorly Tuesday, and IP networks couldnt have done much better, given the redundancy built into legacy networks.
"People trapped in rubble were making calls," TeleChoice analyst Charles Mather said. "Redundancies have been built in for disaster."
The Internet itself fared well. There were some clogs at peering points on the busiest routes, but IP has a basic ability to reroute itself. "The distributed environment of the Internet and ability for IP to handle some time sensitivity and some latency was acceptable," Mather said.
Proponents of VoIP are pushing for one or two standards on which the industry can agree, but thats at least two years away, said Betsy Yocom, managing editor at Meir Communications, which tests and reports on VoIP equipment.
Meir doubts that a VoIP system would have handled the flood of voice traffic Tuesday much better than the PBX system did. The circuit switch network slowed, but it didnt crash, on Tuesday, and thats probably what would have happened if everyone used VoIP, said Yocom.
"If everyone in the country wants to get on the phone at once, youre going to experience problems," regardless of the technology, simply because networks arent built to handle the equivalent of the 100-year flood, Yocom said.
Lloyd Taylor, vice president for technology and operations at Keystone Systems, which monitors Internet performance, agrees that VoIP probably couldnt have handled the rush of calls much better.
"No network is designed for everybody being on it at the same time," Taylor said. "We couldnt afford the phone bills if they did that."