Computer glitches which knocked 5 million Chesapeake & Potomac customers off the line last week, repeated in California and Pennsylvania, have sparked new questions about telephone reliability. Just as the U. S. Telephone Association was lobbying Congress for new laws to let phone companies into new lines of business, the lines serving regular phone service were locking up.
A faulty circuit board is the chief suspect. The board was not installed in the regular telephone switch, but in Signaling System 7, a sophisticated external network which directs traffic between telephone exchanges. The system is supposed to speed calls; where old-style networks connect voice circuits for every call, even if the called line turns up busy, System 7 avoids bottlenecks by checking the proposed route first, then ordering connections when all's clear. It's still new, but it's faster and it makes possible many new services.
Last Wednesday, however, System 7 computers in Baltimore, Hyattsville, Washington and Richmond went down, blocking linkages between local exchanges. Calls moving through a single switch could still get through, but transfers to another switch failed. That brought immediate questions whether the telephone companies were adept enough to handle the new technology as well as the new businesses they want to start. As one regulator put it, they should tend to their own knitting, providing plain old telephone service.