“Certain phrases people use and idioms are important,” said an executive at a large American company that handles service calls through the Philippines. He spoke on the condition that he and his firm not be identified. “We are getting better at it, but of course it is still a hot button.”

Analysts said call centers in the Philippines appeared to have helped American businesses respond to complaints from consumers who said they could not understand Indian agents. But it is unlikely to satisfy critics who say outsourcing is sending too many jobs abroad as millions of Americans struggle to find work.

This year, for instance, US Airways stopped outsourcing customer service to Manila and hired 400 agents in Arizona, California and North Carolina as part of an agreement with the Communications Workers of America union.

Some American companies like Delta Airlines have said they moved call centers back to the United States to appease angry customers who wanted better English. Entry-level American call center agents earn about $20,000 a year, about five times as much as similar agents in the Philippines and six times as much as Indian agents.

Nevertheless, the financial benefits of outsourcing remain strong enough that the call center business is growing at 25 to 30 percent a year here in the Philippines, compared to 10 to 15 percent in India, according to Salil Dani, research director at the Everest Group, a firm that tracks the market.

American outsourcing or back-end companies like I.B.M., Accenture and Convergys along with Indian firms like Aegis, Infosys and Tech Mahindra have thousands of employees working from gleaming glass towers and even inside malls, which executives say young workers prefer so they can be close to shops and restaurants.

In addition to language skills, the Philippines has better utility infrastructure than India — so companies spend little on generators and diesel fuel. Also, cities here are safer and have better public transportation, so employers do not have to bus employees to and from work as they do in India.