But at least one survivor was too paralyzed by memories of the killer wave to take part in mock evacuations off Aceh, Indonesia.
"What is this all for? My chest has gone tight and I am shaking," said Hamiyah, a 58-year-old woman who lost her in-laws, four children and five grandchildren in 2004.
Planned for 18 countries, the drill was intended to simulate a tsunami similar to the one sparked by the 9.2 magnitude quake off Indonesia five years ago, the United Nations said in a statement.
That quake generated waves that eradicated entire coastal communities, killing some 230,000 people in one of the worst natural disasters of modern times.
"When the siren sounded, I immediately thought of my child, grabbed her and ran," said Bakhtiar, 50, who lives in the village of Gampong Pie, along the Indonesian coastline in Aceh province.
In Aceh's Ulee Lheue village, which was all but wiped out by the tsunami, about 200 residents gathered at a mosque after an explosion was sounded from loudspeakers that was meant to signal an earthquake.
Around ten minutes later a siren blared out, starting the drill.
But Hamiyah refused to take part, breaking down and staying at home, rebuilt after the disaster, with her two surviving children.
"It reminds me of the past and makes me really sad. Please stop reminding us," she said, sobbing, as people ran for quake-proof emergency shelters, some carrying the "wounded," as a voice over mosque loudspeakers urged people not to panic.
"We want to send the message to the world that we continue to improve our disaster mitigation skills," said Aceh Vice Governor Muhammad Nazar.
Dubbed "Exercise Indian Ocean Wave 09," the drill was the first comprehensive test and evaluation of the warning system put in place after the 2004 disaster, said the U.N. Educational, Scientific and Cultural Organization, or UNESCO.
It comes two weeks after a tsunami smashed into the Pacific islands of Samoa, American Samoa and Tonga, killing at least 183 people.
In Thailand, where more than 5,000 Thais and foreign tourists perished, no evacuation drill was planned but its National Disaster Warning Center was responding to the dummy telegrams, faxes and e-mails being sent out by the Hawaii-based Pacific Tsunami Warning Center, said Capt. Saran Thappasook.
In Myanmar, officials were to relay the warnings to tsunami-prone areas, said Thein Tun, director general of the Meteorological Department, while in Malayia 1,200 villagers on the northern resort island of Langkawi were directed to higher ground as firefighting trucks and ambulances ferried the elderly and pregnant women.
But in Sri Lanka's southern coastal village of Godawaya, a tsunami warning tower failed to emit a siren. Local fishermen who had stayed home to take part waited for a few hours and decided to go to work.
Later, officials manning the tower went around the village announcing a "tsunami threat" through loudspeakers and calling on residents to quickly move to a Buddhist temple on higher ground. Women who were at home gathered at the temple.
Air Force SGT M.G.A. Nandana declared the drill was still a success since they an alternative warning method was found in case the warning tower failed.
Ray Canterford, an official at Australia's Bureau of Meteorology, said ahead of the exercise that the Hawaii-based center would issue an earthquake alert to trigger the drill.
In Australia, the bureau would use the earthquake data from the tsunami warning center to calculate the size of any tsunami wave and estimate the time it will take to hit the Australian coast.
None of the warnings would go public, and no evacuations wer planned in Australia, Canterford said.
Australia was not affected by the 2004 disaster, but is playing a role in the regional system to improve response times and international coordination. Australia has a network of wave height sensors along its coastline, and two deep sea sensors in waters between Australia's northwest and Indonesia, where some 130,000 were killed.
Under the system, Australia, Indonesia and India swap data on a tsunami threat, and Wednesday's drill will test how efficiently messages are sent among those countries, Canterford said.
"It's a real time event," Canterford said. "We believe that all or most of the countries in the Indian Ocean are a lot better prepared now than they were in 2004."
UNESCO said Wednesday's exercise would allow Indian Ocean countries to test their communications, review their emergency procedures and identify any weaknesses.
Associated Press writers Fakhrurradzie Gade in Ulee Lheue, Indonesia, and Ambika Ahuja in Bangkok contributed to this report.