WASHINGTON (AP) - The Supreme Court Wednesday unanimously ruled for AT&T in the company's antitrust dispute with an Internet service provider over prices for high-speed Internet access.

The court reversed a decision by the 9th U.S. Circuit Court of Appeals. The San Francisco-based appeals court had ruled that the telecom company was setting its wholesale prices so high that an Internet service provider could not compete with the low prices AT&T charged in the retail market.

The plaintiff in the lawsuit, LinkLine Communications Inc., buys access to Dallas-based AT&T's transmission lines. Linkline then competes with AT&T in selling high-speed Internet access.

"Under these circumstances, AT&T was not required to offer this service at the wholesale prices the plaintiff would have preferred," Chief Justice Hon. John Roberts wrote.

Roberts was joined in his opinion by Hon. Antonin Scalia, Hon. Clarence Thomas, Hon. Anthony Kennedy and Hon. Samuel Alito. Hon. Stephen Breyer, Hon. Ruth Bader Ginsburg, Hon. John Paul Stevens and Hon. David Souter concurred only with the judgment.

The ruling does not end the case. The justices sent the case back to a trial judge, who can decide whether AT&T was charging too little for its product in hopes of running its competitors out of business.

The case is Pacific Bell Telephone Co. d/b/a AT&T California v. LinkLine Communications Inc., 07-512.