According to an MCI WorldCom spokeswoman, frame relay data service has been slow or unavailable across close to 15 percent of the company's nationwide network. The outages affected users in metropolitan cities like Chicago and San Francisco, as well as in much of the northeastern United States.
The problems were first reported Friday morning, and continued through today, the company said. A spokeswoman said most service has been restored, but "congestion" in the system was still slowing or altogether halting some access.
Frame relay carries data in much the same way as it is carried along the public Internet, breaking messages and files into small "packets" of information which are reassembled once they reach their destination. The service is widely used by businesses.
According to MCI WorldCom, the network problems began as a part of an upgrade to the company's nationwide frame relay network. This afternoon, the company still had not isolated the source of the problem.
"We're still working with our equipment vendors," said Linda Laughlin, a company spokeswoman. "We have not yet identified the root cause."
MCI WorldCom maintains individual contracts with its customers that will govern how the company makes reimbursements for lost service, Laughlin added.
The company had no estimate as to how many individual customers were affected.