The 1-800-Medicare line is a critical resource used by millions of elderly and disabled Americans, as well as their family members. Tens of thousands of people call the number each day, and on some days, the number of calls can exceed 100,000.

Investigators randomly contacted beneficiaries and others who had called the hot line one week in late January. They found a satisfaction rate of 71 percent, which is a drop of 13 percentage points when compared to a similar series of interviews conducted three years earlier.

Volume to the hot line has increased significantly as the Bush administration rolled out a new drug benefit under Medicare. The percentage of callers who said they had some difficulty accessing information remained about the same this year as in 2004 -- 44 percent.

However, more callers hung up before getting responses during the latest survey. More than one in five callers hung up before having their questions answered. Two-thirds of those who hung up did so because of long wait times.

Rep. Pete Stark, D-Calif, said the performance of the private contractors hired to run the hot line disappointed. The name of the contractors was not provided in the report. A footnote in the report said, however, that since the survey was conducted, just one contractor has assumed oversight of all the 1-800-Medicare call centers.

Agency officials stressed that a majority of callers were still satisfied with the help they got, and the agency was working to improve performance.

"We expected some challenges with regards to queries involving the rollout of a brand new, nationwide program involving millions of Medicare beneficiaries," said CMS spokesman Jeff Nelligan.

Stark asked Kerry Weems, the new acting administrator at the Centers for Medicare and Medicaid Services, to explain what measures the agency and contractor is taking to improve call center responses.

In the Medicare agency's official response to the inspector general's findings, which was included in the report, officials said they will be conducting a study to help determine why callers are not getting the information they need. The agency will also work to simplify choices they are provided to customers before they are transferred to a live operator.

The inspector general's primary recommendations was to reassess whether adequate resources are directed toward improving the capabilities of the automated system. Only five of 206 called successfully received an answer to their question from the automated answering system.