A hacker who broke into the systems of T-Mobile USA and lifted the personal details of around 400 people, including a US Secret Service agent, has escaped imprisonment.

Nicholas Lee Jacobsen, 23, was sentenced to one year of home detention and a fine of $10,000 in compensation to T-Mobile over the 2004 attack.

Even though Jacobsen was left able to access personal data held by Special Agent Peter Cavicchia on a sidekick mobile device, the Secret Service is ruling out the possibility that any investigations might have been compromised.

Jacobsen is thought to have tried, but failed, to get access to credit card details. This failure, along with his youth, counted in his favour when he came before Judge George for sentencing at a Los Angeles court on Monday.

"I did some very stupid things," Jacobsen told the judge, AP reports. Jacobsen pleaded guilty to unlawful access of a protected computer, an offence punishable by up to five years imprisonment. ®