A private initiative involving all phone companies here began monitoring mobile phones with international roaming and traced the call patterns to figure out the location of the phone users.

"There were 10,252 international roaming phones working on Sri Lankan networks at the time of the tragedy," Chris Dharmakirti, who is heading the Tidal Wave Rescue Centre said. "We sent everyone an sms and got responses from 2,321.

"Whenever anyone used the phone, we could track where the person was and restrict our search to affected areas of the country."

"Some people who called us did not know where they were. All they could say was they were on high ground. But we were able to pin-point from where the call was coming and could rush help," [Dharmakirti] said.

"This is the first time in Sri Lanka that we have used high tech call tracking for a rescue mission. It has been highly successful and the teenagers who manned the call centre were themselves keen to go out and help victims," he said.

"What we are doing is to use this to help any survivor who is marooned and needs help."