Almost half of the phone links that handle calls for Chesapeake & Potomac Telephone Co. in the Washington area broke down momentarily Wednesday for reasons C&P; engineers still can't explain.
Service was not disrupted by the glitch, which comes on the heels of two major regional phone outages -- one affecting Maryland and one in Pennsylvania -- that also remain unexplained.
Fred Howard, director of network operations for C&P; in Washington, said that 68 fiber-optic links were momentarily taken out of service Wednesday after computers noticed trouble on the lines. The links, which cover one mile to 100 miles each, connect central offices in Washington, Virginia and parts of West Virginia with supercomputers that sort and route calls across C&P;'s network.
The links are an integral part of C&P;'s "Signaling System 7" (SS7) network: The links carry information about calls to central computers, which in turn tell electronic switches the fastest route touse to complete a call. On Wednesday, 68 out of 150 central offices were affected by the glitch.
SS7 is state-of-the-art network that broke down in Maryland on June 26 for reasons that continue to elude engineers.
That outage, which also affected Washington, Virginia and parts of West Virginia, left up to 5 million people without phone service for most of the day.
During Wednesday's momentary breakdown -- which lasted for less than a second -- phone traffic was switched to backup lines by computers built by DSC Communications Corp. of Plano, Texas. Those are the same computers that have been blamed in part for the massive outage on June 26.
Had the computers and their backups not functioned properly, Mr. Howard said, C&P; could have been looking at another wide-scale outage. As it turned out, he said, the glitch was not noticeable to customers.
"This has given us reassurance that the fixes that have been put in
place by ourselves and by our vendors are working well," Mr. Howard said.
He said that it isn't unusual for phone links to go downor be taken out of service for a myriad of reasons.
But he said it is unusual for so many links to fail at the same time.
That being the case, Mr. Howard said C&P; engineers are poring over computer printouts to find out what caused Wednesday's problem.
"We are trying to get to the bottom of this, not because it affected anything, but because it came to our attention and we want to have more information about it," he said.