Four employees at a Pennsylvania staffing company have admitted they scammed the visa system to bring hundreds of seasonal workers into the U.S. for clients.

International Personnel Resources applied for temporary work visas under phony names culled from a Mexican phonebook, and its employees used the stockpiled documents to place workers from Mexico and Central America in landscaping and other jobs, authorities said.

At times, the company sent undocumented workers home, supplied them with visas and coached them to tell immigration officials they had never been in the country illegally, prosecutors said.

Former office manager Emily V. Ford, 29, of West Chester, pleaded guilty Wednesday, Assistant U.S. Attorney Kevin Brenner said.

Company owner and President Michael T. Glah, 48, and his wife, Vice President Theresa M. Klish, 50, both of West Chester, and office manager Mary H. Gillin, 60, of Downingtown, pleaded guilty Tuesday in Philadelphia federal court to charges in the 11-count information.

All four are set for sentencing on March 29. Glah faces a mandatory five-year prison term. The others face prison terms under federal guidelines, Brenner said.

Glah's lawyer, Robert J. Donatoni, called his client remorseful.

"There will come a time when they will articulate why this happened," Donatoni said. "Obviously, there will be no justification for it."

Gillin's lawyer declined to comment; the other defense lawyers did not immediately return messages left by The Associated Press.

H-2B visas are designed for companies that cannot find Americans willing to fill their jobs.

The West Chester-based company accumulated hundreds of H-2B visas for arriving workers from 2003 to 2008.

The defendants took advantage of a provision in the law that lets employers substitute new names if the original applicant becomes unavailable. Given the cap of 66,000 visas annually for such workers, their scheme left fewer available for companies trying to use the system lawfully, prosecutors said.