Hackers have posted the mobile phone address book of hotel heiress and amateur porn celebrity Paris Hilton on the Internet, putting the phone numbers and e-mail addresses of, among others, Eminem and Christina Aguilera in the public domain. The breach could be a valuable security lesson for individuals and companies using any kind of mobile data.

A copy of Hilton's T-Mobile mobile phone address book appeared on the website of a group calling itself "illmob". The address book contains information on over 500 of Hilton's acquaintances. It is not known how the information was obtained, but the release of the contact book may be further fallout from a hack of T-Mobile's servers that came to light last month.

A second site posted all the details plus photos taken using the phone's in-built camera by Ms Hilton, plus several emails sent through the device.

The Hilton address book is a simple HTML table listing the phone numbers and e-mail addresses for acquaintances, along with other useful information, such as the number of the San Francisco Hilton Hotel and celebrity attorney Robert Shapiro.

The leak is bound to prompt a furious round of unplanned number changes among Hilton's coterie, after fans and curious Web surfers learned of the hack and began dialling their favorite celebrities.

Eminem's phone number was changed. Limp Bizkit front man Fred Durst's voice mailbox was full. Tennis star Anna Kournikova's number was busy, despite repeated attempts to get through. Robert Shapiro's answering machine picked up when called and provided a number to page the star attorney in an emergency.

There was no answer at Hilton's home, nor did sister Nicky Hilton answer calls to her phone. Reached by phone, actor Kevin Connelly, of the cable television show "Entourage," said he had received between 200 and 300 phone calls since early Sunday, as word of the hacked address book spread across the Internet. Connelly plays opposite Adrian Grenier in the HBO show about a young celebrity and his colorful entourage of old school chums. He declined to comment on whether he knew Hilton or why his name appeared in her T-mobile phone list.

Connelly, who received at least one other call while on the line with this reporter, said he would likely change his phone number Monday to stop the harassment.

It was unclear Sunday how the cell phone contact list was obtained. However, Hilton's was one of a number of celebrity cell phones that was reportedly compromised in an attack on T-Mobile's network that netted information on 400 of the company's customers, including sensitive information from the account of a US Secret Service agent.

In January, the mobile carrier acknowledged that Nicholas Jacobsen, a California-based hacker, compromised its internal computer systems in 2003 and viewed the Social Security numbers of 400 customers. T-Mobile has yet to respond to requests for comment.

Jacobsen pleaded guilty last week to one felony charge of accessing a protected computer and causing reckless damage. He is scheduled to be sentenced in May and faces a maximum possible sentence of five years imprisonment and a $250,000 fine.

What does it mean to your company? Read our assessment of the lessons companies can learn.