Hampden Telephone Co. has been purchased by TDS Telecom of Madison, Wis.

TDS is a subsidiary of Chicago-based Telephone & Data Systems, an operator of telephone, cellular and radio paging companies.

Hampden Telephone, which has 2,600 customers in Hampden and Etna, has been controlled by the Gamble family since the late 1950s. When Lawrence Gamble died about five years ago, controlling interest in the company was inherited by his children, Lawrence, Leslie, Laura and Linda. Linda Gamble has been serving as president.

Linda Gamble said Monday that it was difficult for her family to keep the company because it was an “asset you don’t get much return on.” She also said there was a trend for smaller public utilities to be bought by larger companies.

During recent years, Hampden Telephone was a target of regulators.

In late 1992, the Maine Public Utilities Commission launched an investigation into the company. Specifically, the PUC looked at charges that the Gambles were using company funds to pay for personal expenses including gasoline, meals, groceries, travel, gifts and entertainment.

In the end, the PUC never determined whether Hampden Telephone or its owners had violated Maine law. But the state regulators imposed a financial penalty on the utility. Members of the Gamble family were to repay $17,341.11 in “personal and undocumented charges” that had been made on company credit cards.

Thomas Welch, PUC chairman, criticized the Gambles for “the private fiefdom attitude that seems to have taken hold of the company.”

Terri Hayes, a spokesperson for TDS Telecom, said her company owned 100 companies that served 600 communities and 400,000 customers in 29 states.

She said Hampden Telephone would continue to operate under the same name and with many of the current employees. Linda Gamble will be general manager, Hayes said. According to TDS, it will strengthen Hampden Telephone with its operations experience, technical resources and financial backing.

Telephone & Data Systems, the Chicago parent of TDS Telecom, has 4,400 employees. Its stock is traded on the American Stock Exchange.