Washington ? Federal regulators fined SBC Communications Inc. $6 million Wednesday for violating the terms of its 1999 merger with Ameritech, a Midwest phone company.

The Federal Communications Commission said an investigation prompted by competitor complaints found that San Antonio-based SBC tried to restrict the ability of carriers in five states to share its network.

“Such unlawful, anticompetitive behavior is unacceptable,” FCC Chairman Michael Powell said. “Instead of sharing, as the law requires, SBC withheld and litigated, forcing competitors to expend valuable time and resources.”

James Smith, an SBC vice president, said in a statement that the company believes the FCC had “mistakenly interpreted not only the letter, but also the intent” of the merger condition on sharing. He said the company was reviewing the FCC’s action and was considering what to do next.

SBC is the parent company of Southwestern Bell, which provides service in Lawrence.