From dusk to not-quite dawn, they operate on the world's schedule. Hey, taxi!

NEW DELHI - The tiny white cab speeds through the mind-numbing maze of buses, cars, rickshaws, motorcycles, street entertainers and beggars. Once inside a neighborhood, it zips past cows, children playing cricket, and women lining up for water.

Monu Sharma, the driver, honks the horn at every moving thing on the road, changing lanes and snaking his way around all the obstacles.

Today, as on most days, Sharma is on a tight deadline, trying to get three employees to a suburban New Delhi call center where they work for a company, Quatrro, that provides technical support to computer users in the United States. Their shift begins at 7 p.m. and lasts until dawn. Sharma reaches his first pickup at 4:30 on a humid, windless afternoon.

He has contracted with India's booming call centers for six years, picking up and dropping off employees all day and night in his cab. It is a stressful job, Sharma says, because time is crucial to his clients' business. Still, he is grateful he isn't working as a personal driver at a client's residence.

"I don't have to be servile, saying, 'Yes, sir,' and 'Yes, madam,' all day and carry my boss' briefcase everywhere," he said. "In this job, I just focus on the time and the road."

The first employee to be picked up is Tapasya Arya, a young woman wearing a crisp, white cotton shirt and jeans. She carries her purse and a red gym bag.

"I go to work when everybody is returning home," Arya, 24, said, climbing into the back. As the cab sped off to its next pickup, she could see the rush-hour madness and hear the blaring horns.

"Call-center employees sleep so little; we work all night and get home at dawn," said Arya, who is relieved the cab has air-conditioning today. "I am hardly able to catch up on my sleep in the day because the doorbell rings constantly. It is easier to sleep in the AC cab, in spite of the bumpy and noisy traffic."

Owais Khalil Khan, the second employee picked up, says he has learned to manage on five hours of sleep at a time.

"Sometimes our driver falls asleep on the wheel driving us back at dawn," Khan said. "I turn on the radio loud, so the music wakes him up."

It takes Sharma more than an hour to collect all three employees. Finally, he and his passengers are on their way to Gurgaon, a New Delhi suburb choked with glitzy, glass-fronted call centers and malls.

In previous call-center jobs, Arya says, she used the name Tammy when speaking to Americans. But as the industry matures, she says, companies have become more open about where they are based.

"Now I tell them I am Tapasya and their call has been routed to India," she said.

At 7 p.m., the employees are dropped off outside a building labeled "Quatrro - Beyond the Existing."

When Sharma returns at 4:30 a.m. to pick them up, it is still dark and the district is teeming with hundreds of white cabs buzzing outside call-center buildings. Thousands of workers emerge after a long night of fixing the world's banking, computer and accounting glitches.

The chatter that filled the cab on the way to work is absent. The workers are sleepy.

Arya calls her mother and tells her she will be home in an hour to go to her yoga class. She says she searched the Internet for diet recipes during her break.

"I got three calls from Richard today," Khan said, speaking of a new American customer. "We fix his computer problems from here. Today Richard said, 'If it wasn't for you guys, I would have died,' " Khan said and settles down to snooze.

Arya looked out at all the call-center vehicles speeding past.

"At this hour, there are only call-center cabs on the road," she said. "I told you we are a breed apart. The aliens are out in the night."