United States' telecommunications networks were returning to normal on Wednesday, after lines were jammed as millions of Americans desperately tried to contact relatives and friends after the attacks on the World Trade Center and the Pentagon.
The record volume of calls to the New York and Washington areas on Tuesday brought telephone networks to a standstill, preventing millions of people from getting through.
AT&T, the largest US long-distance carrier, said its long-distance network carried an average of four million calls every five minutes after the attacks - double the normal volume.
Telephone companies urged customers to avoid making non-essential phone calls to the affected areas so that emergency calls could get through.
Wireless networks suffered the same congestion. Many people trying to reach friends and relatives from mobile phones were unable to make or receive calls.
In New York, survivors of the attack stood in long lines near banks of pay phones as they tried to reach relatives to tell them that they were safe.
Several people caught under the rubble reportedly used their cell phones to call for help.
Callers throughout Europe had difficulty reaching numbers in the US following the attacks. The number of calls from Switzerland to the United States was double the normal daily average.
A spokesman for British Telecommunications said its network was trying to cope with 250,000 calls from the UK to the US every 15 minutes - more than 10 times the normal volume.
Much of the Internet was also crippled on Tuesday, as traffic soared in the wake of the attacks. In the United States, some sites added servers and dropped heavy graphics and interactive features to focus on text reporting so that they could accommodate the volume.
MSNBC.com, the joint venture between Microsoft and NBC saw its traffic increase tenfold over its average daily use of three million users.
A rush of Internet users seeking the latest news also snarled major European news sites. Swisscom spokesman, Christian Neuhaus, said there was a slowdown in Internet performance in Switzerland.
swissinfo's site was also affected, and a temporary reduced service was put it place to speed up connections so users could access the latest news with minimum delay.
With phone lines inundated, many Americans turned to the Internet to inform friends and relatives by e-mail that they were safe. Pagers, capable of sending and receiving wireless text messages, also proved reliable.
Postal connections between Switzerland and the United States have been severely disrupted in both directions following the cancellation of flights.
swissinfo with agencies