An AT&T spokesperson said the company is expanding a trial program it had with the movie industry to other copyright holders.

Under AT&T’s new policy, copyright holders will send notices containing users’ I.P. addresses to the company if infringement is suspected. Distributing songs through a peer-to-peer file-sharing network could result in a notice. AT&T will then match the addresses to actual user accounts and send notices to those accounts.

At this point it’s up to the users and the copyright holders. If users ignore warnings, AT&T will not identify or disconnect users, and copyright holders will still have to get a court order forcing the company to name names.

By not threatening disconnection, AT&T is veering from an emerging model in Europe, popularly referred to as “3 Strikes,” where suspected infringers get three warnings before service is cut. Instead, AT&T is leaving any course of action, including lawsuits, up to the intellectual property owners.

In Ireland, ISPs disconnect users repeatedly fingered as entertainment pirates. The RIAA has already sued one local ISP, forcing it to disconnect users after three notices.

AT&T’s move marks a major change in the way the recording industry fights music piracy. Gone are the thousands of monthly lawsuit threats where the RIAA would give suspected music pirates the choice of facing litigation or settling cases by paying fines to the labels, usually in the neighborhood of $3,000 to $5,000.

However, when the RIAA announced it would cease suing individual users, the trade organization said it would shift its efforts to working with ISPs. Comcast, Cox Communications and Verizon Communications already forward copyright notices to users.

“It seems to engender a good response from customers, and we’ve seen a fairly dramatic drop-off in file-sharing activity once people receive a notice, so we feel this works,” said Jim Cicconi, AT&T’s senior executive VP of external and legislative affairs.