But insurers' efforts to ready their systems are being hampered by the sluggish pace at which many health care providers are adopting the new numbers, IT executives at more than a half-dozen Blue Cross and Blue Shield health plans said last week.

The Health Insurance Portability and Accountability Act, which was approved in August 1996, mandates that all health care providers covered under the legislation obtain a 10-digit National Provider Identifier number to use in certain transactions. Large insurers -- most of which now use multiple internal ID numbers to track providers -- must begin processing documents with the NPIs by May 23, 2007. Smaller health plans have another 12 months to comply.

Blue Cross and Blue Shield of North Carolina plans to make the required changes to its IT systems and business processes by September. However, the Durham-based company estimates that only 20 percent of the doctors and hospitals it works with have applied to the federal government and received their new ID numbers, according to Harry Reynolds, the insurer's vice president of information systems planning.

That is making it difficult for Blue Cross and Blue Shield to ensure that it's effectively altering its systems so they can accept the new numbers, Reynolds added.

"Until we see some of the large institutions taking their numbers, whether we have everything covered ... will have to be determined," he said. "No one can declare victory, because the other part of the equation is sitting out there in a bit of an unknown. We don't think we will get shocked, but we could still get surprised."