SBC was having problems with a server that helps provide DSL (digital subscriber line) service in an area running from California's Central Valley to the Oregon border, a company representative said.
The company said it did not know the cause of the glitch.
The server authenticates customers before allowing them onto SBC's DSL network. The glitch caused an "intermittent outage," barring people from logging on, the representative said.
Customers were encouraged to make continued login attempts if their first efforts didn't work, said the representative, who added that the network itself, once reached, is working fine.