SILVER SPRING -- Chesapeake & Potomac Telephone Co. officials now believe a failure in a circuit board in a master computer in Baltimore triggered the chain of events that led to the massive breakdown in the region's local network Wednesday.
Larry Plumb, a spokesman for Bell Atlantic Corp., the parent company of C&P;, said circuit boards in master computers break down frequently. But he said those breakdowns typically don't produce such catastrophic results.
"Circuit boards quit all the time, but obviously we've never had anything like this happen before," Mr. Plumb said.
Bell Atlantic has formed a task force of several hundred people to study the breakdown, Mr. Plumb said. The group is composed of representatives of C&P; Bell Atlantic; Bell Core, the research arm of the Bell telephone companies; and Digital Switch Corp. of Plano, Texas, the hardware manufacturer.
Mr. Plumb said the task force plans to meet throughout the weekend to try to isolate the problem that led to the problem.
At a press briefing yesterday, Delano Lewis, president of C&P; Telephone Co. of Washington, said an announcement probably will be made Monday detailing how the C&P; phone companies plan to compensate customers for their loss of telephone service.
Options being considered include giving customers refunds or creditson their monthly bills.
Under Maryland law, C&P; is not required to give rebates to customers unless service is lost for more than 24 hours. Wednesday's outage lasted for about eight hours, from 11:30 a.m. to about 7:30 p.m.
During yesterday's press briefing at C&P;'s Chesapeake facility in Silver Spring, officials said they think a circuit board in a computer in Baltimore quit functioning properly and began flooding the computer with "maintenance" messages, which the computer sends to itself to confirm that its components are working properly.
The volume of maintenance messages flooded the computer, the officials said, causing it to shut down. That set in motion a chain of events that eventually caused three other master computers, which are used to sort and route calls, to shut down.
The breakdown left up to 5 million people in Maryland, Washington, Virginia and parts of West Virginia without local phone service.
Three days later, C&P; officials still don't know why it happened.