TUCSON - Defense contractor Boeing Co. has told the government it believes it has solved most of the problems that have delayed use of the first section of a high- tech "virtual fence" along the nation's borders for months.

U.S. Customs and Border Protection officials, however, said they'll wait until acceptance testing now set for late October is done before passing judgment.

The 28-mile section of fence along the U.S.-Mexico border in Southern Arizona is the first of thousands of miles planned on the nation's southern and northern borders.

Boeing personnel who briefed federal officials "sounded real optimistic" about the fixes, Brad Benson, a Customs and Border Protection spokesman in Washington, said Wednesday. "I have talked to Border Patrol personnel, and they weren't quite that optimistic."

A spokewoman for the Boeing group building the fence wasn't immediately available for comment.

Operation of the nine 98-foot towers north of the Arizona-Mexico border near the port of entry at Sasabe has been delayed for at least four months because of computer software glitches.

Loaded with sensors, radar and sophisticated cameras, the towers are designed to detect illegal immigrants and drug smugglers coming through the heavily trafficked area southwest of Tucson.

The $20 million virtual fence pilot project remains on hold because software designed to integrate the results of sensor hits, radar readings and camera sightings wasn't working correctly.

A glitch in the programming has kept it from providing a common operating picture for agents, who plan to use it to spot and capture illegal entrants and smugglers.

Because of that, Homeland Security Secretary Michael Chertoff told a Congressional committee last month that he would withhold further payment to Boeing, the prime contractor, and declined to accept the system until he was satisfied.

He called acceptance testing "a little bit like buying a car.

We didn't want to get stuck with a lemon," he testified.

That testing is now set for the last week in October, Benson said.

The virtual fence is being tested first in Arizona, the focal point for illegal crossings into the United States from Mexico.

But plans call for installing 1,800 such towers along both the Mexican and Canadian borders.

Benson said Border Patrol agents have employed some of the towers' equipment to assist in apprehensions of illegal immigrants.

But that doesn't mean all systems are functioning in an integrated manner or that agents are seeing one common picture as intended, he said.

"There's some usefulness there, but it's still not there," Benson said.

Even if the system passes, other tests may follow, and other faults may crop up during operation.

"Our guys have said the true test of whether we're accepting it is whether the Border Patrol is using it," Benson said.

"It's not ready for prime time. We still have a little way to go."