31 ;;Quote: used two years of outage records to study failures of the US Public Switched Telephone Network

31 ;;Quote: overloads of the telephone network caused almost half of the outage minutes; human error and acts of nature where other major causes

31+;;Quote: software errors caused less downtime of the telephone network, 2%, than any other source of failure except vandalism

36 ;;Quote: half of the software in telephone switches concerns error detection and correction; this may explain the low outage rate due to software

36 ;;Quote: human intervention was able to correct many failures of the telephone network in under one hour

36+;;Quote: restarting a telephone switch temporarily fixed a significant number of software-caused outages