TAIPEI, Taiwan - Taiwan's largest telecom company said Friday it will not invest more in backup lines to protect against disasters like the recent earthquake that snarled telephone and Internet service across Asia, affecting service as far away as the United States.

The quake, which damaged undersea cables off Taiwan on Tuesday, was so rare that there is no need to spend money on extra lines, said Wu Chih-ming, a senior official at Chunghwa Telecom Co., Taiwan's largest telecommunications company.

Taiwan's Central Weather Bureau measured the quake at magnitude 6.7 while the U.S. Geological Survey put it at 7.1.

"We won't consider laying more backup cables for now because such an incident might not happen in another 100 years," Wu said.

On Friday, companies from Japan to Singapore were still scrambling to fully restore service. Since it will take weeks to repair the cables off Taiwan, companies were rerouting traffic through satellites and cables that were not damaged. Many of the cables are owned by groups of telecom companies, who share the costs and capacity.

The telecom crisis stunned Asia and demonstrated how tightly the region is bound together by hundreds of undersea fiber-optic cables.

The lines, made of clusters of glass fibers wrapped in protective material, carry Internet data and voice calls as pulses of light.

South Korea's largest telecom company, KT, said it worked through the night with Singapore Telecommunications Ltd., or SingTel, to restore damaged lines.

"KT and SingTel worked through Thursday night to upgrade the service," Sung Won-jae, a KT spokesman said.

Internet access to international Web sites, as well as services for Blackberry mobile devices, had been fully restored, SingTel said Friday.

"As part of our redirection effort, cable traffic to the U.S. is being rerouted via Europe or Australia as well as using other channels such as satellite links and landlines," the company said.

Four repair ships were on their way to the damage site and were expected to arrive Tuesday, Chunghwa Telecom said.

Repairs, which would cost about $1.5 million, would take up to three weeks, the company said.

South Korea's KT did not plan on spending more on backup lines to prevent with future disasters because Tuesday's quake was rare, Huh said.

He said the lesson KT had learned was that it needed to restore lines more quickly.

In Japan, major carriers KDDI Corp. and NTT Communications said most fixed-line phone services were running.

In Manila, the Philippines' largest telecommunications company, Philippine Long Distance Telephone Co., and its mobile unit Smart Communications said Friday they had restored "sufficient capacity to handle normal" international voice and Internet data traffic.

"This has been accomplished largely by channeling our traffic flows to alternative routes," PLDT said in a statement.

China, however, seemed to be struggling to get its services up to speed. China Telecom Corp., the country's biggest telephone company, said on its Web site that only 15 percent of the international Internet circuits have been restored, and that "there are still serious problems on the routes to North America."

Tim Dillon, senior research director at U.S.-based Current Analysis, which studies the telecom industry, said customers in Asia will have to get used to slow services for weeks.

"We have a lot of traffic all going to alternate routings at the same time," Dillon said. "It's obviously going to result in slower speeds and congestion as everyone piles onto the same cable."

Associated Press writers Kim Kwang-Tae in Seoul, South Korea, Tanalee Smith in Singapore, and Scott McDonald in Beijing contributed to this story.