WASHINGTON — A group of telephone companies struggling to break into the subscription TV business is urging Congress to limit the ability of the Walt Disney Co., Viacom, CBS and NBC to enter exclusive programming deals.Under pressure from the telcos, the House Judiciary Committee has expanded a hearing for Sept. 24 to include the so-called program access rules. And now the House Commerce Telecommunications Subcommittee is looking for an open date to schedule its second hearing on the same issue. The Baby Bells, led by Ameritech and Bell South, want to broaden the current ban on exclusive programming deals to include companies that do not own cable systems. Those companies include the networks, Disney and Viacom. Although Fox does not own any cable systems itself, much of its programming is jointly owned by cable giant Tele-Communications Inc., and therefore must be offered to any potential buyer. Although the non-cable-affiliated programmers distribute most of their programming as broadly as possible, the studios and networks oppose any effort to limit their ability to make deals. “We want to head off anything going the wrong way,” said one studio lobbyist. Viacom has sold TV Land and Nickelodeon exclusively to local cable systems which compete directly with Ameritech’s cable systems, according to Ameritech officials. But few other examples have been cited by the telcos. Potentially more troubling to programmers than the effort to limit exclusivity is the telcos’ demand for pricing parity with cable operators. Although Ameritech has only 1.6 million subscribers, it is demanding to pay the same price for programming as companies such as TCI and Time Warner, which have more than 12 million subscribers. One of the program access rules’ most powerful advocates is House Telecommunications Subcommittee chairman Billy Tauzin (R-La.), who successfully fought to have them included in the Cable Act of 1992. Tauzin’s original aim was to protect the fledgling satellite TV market by assuring it access to valuable cable programming. At a hearing last month, Tauzin said he would consider additional legislation to broaden the rules.