A California man faces felony charges of hacking into cell phone company T-Mobile's computer network to steal hundreds of names and social security numbers, according to court documents released on Wednesday.

Nicholas Lee Jacobsen was arrested in October, about a year after Bellevue, Washington-based T-Mobile discovered that an unauthorized person had accessed one of its internal computer systems, T-Mobile USA Inc. spokesman Peter Dobrow said on Wednesday.

T-Mobile, a subsidiary of Deutsche Telekom AG, has 16.3 million U.S. customers.

Jacobsen and his lawyer could not be located for comment.

"T-Mobile has stringent procedures in place where we monitor for suspicious activity so that limited his activities and we were able to take corrective action immediately," Dobrow said.

Jacobsen made at least two attempts to breach T-Mobile's system and eventually stole names and social security numbers for 400 T-Mobile customers before the company took steps to stop the incursion, Dobrow said.

The hacker was not able to access credit card data which is stored on a different system, he said.

T-Mobile notified the affected customers and asked the U.S. Secret Service to investigate the incidents, Dobrow said.

Dobrow would not comment on reports that first surfaced in the online SecurityFocus Web site that Jacobsen tried to sell the information in underground hacker chat rooms.

The company said the Secret Service was investigating whether Jacobsen also accessed photos that T-Mobile customers took with the camera function on their phones.

A Los Angeles grand jury indicted Jacobsen on charges of intentionally accessing a computer system without authorization and with the unauthorized impairment of a protected computer between March and October of 2004, the court documents showed.

A U.S. Attorney's Office spokesman said Jacobsen was free on bail and living with relatives in Oregon while awaiting trial.

From Reuters