Repairing the cables harmed by Tuesday's tremor — which killed two people — could take three weeks but "quality will improve day by day," said Lin Jen-hung, vice general manager of Chunghwa Telecom Co., Taiwan's largest phone company.
The 6.7-magnitude quake — which triggered a tsunami alert — damaged two of the seven undersea cables near Taiwan used by several countries to route calls and Internet traffic, Chunghwa said. Crews fixing the cables would have to pull them up and transfer them to a ship for repair, the company said.
The damage to the two lines, located in the south, cut off 50 percent to 60 percent of Chunghwa's overall telephone capacity, the company said. Most severely affected were connections to China, Japan and Southeast Asia, it said.
Also hard hit was telephone service to the U.S., where 60 percent of capacity was lost, the company said.
Chunghwa also said 98 percent of Taiwan's communications capacity with Malaysia, Singapore, Thailand and Hong Kong was disrupted.
Hong Kong telephone company PCCW Ltd., which also provides Internet service, said the quake cut its data capacity in half. Many Internet users were unable to access Web sites in parts of America, Taiwan and South Korea. Calls to Taiwan weren't connecting.
Internet access has been cut or has become extremely slow in Beijing, said an official from China Netcom, China's No. 2 phone company.
The official, who would not give his name, said the cause was thought to be the earthquake, but he had no further details.
Businesses in various parts of the city also said they were experiencing Internet access problems.
CCTV, the state-run television network, said China Telecom Corp., China's biggest phone company, was contacting counterparts in the U.S. and Europe about using satellites to make up for the shortfall.
KDDI Corp., Japan's major carrier for international calls, said its fixed-line telephone service was affected by the quake. Company spokesman Haruhiko Maeda said customers were having trouble calling India and the Middle East, which are usually use the cables near Taiwan. Maeda said the company was rerouting calls to go through the U.S. and Europe and the company did not know how long it will take to repair the cables.
Japan's Ministry of Internal Affairs and Communications said that international roaming service provided by Japan's major three telecommunications — NTT DoCoMO, KDDI, and Softbank, was affected. Ministry official Akira Yamanaka said that some customers were unable to make calls using their mobile phones in countries including Taiwan.
South Korea's largest telecom company, KT, said that lines it uses were damaged, affecting dozens of companies and institutions, including South Korea's Foreign Ministry.
However, the quake didn't cause problems for ordinary people using Internet and telephone service, according to Ku Ja-hong, a KT spokesman.
The quake, which hit offshore from the southern town of Hengchun, came on thethat killed more than 200,000 lives in southern Asia.
Tuesday's tremor was felt throughout Taiwan. It shook buildings and knocked objects off the shelves in the capital, Taipei, in the northern part of the island.
Two members of one family were killed in Hengchun when their four-story home collapsed. The quake injured 42 people, three homes collapsed and 12 fires broke out, the National Fire Agency said.
Quakes frequently shake Taiwan, which is part of the Pacific's "Ring of Fire," an arc of volcanos and fault lines encircling the Pacific Basin. Most are minor and cause little or no damage. However, a 7.6-magnitude earthquake in central Taiwan in September 1999 killed more than 2,300 people.