The FCC’s Cybersecurity and Communications Reliability Division (Division) has released a report scrutinizing Level 3 Communications’ (Level 3) major network outage. The Division stated that the outage was the largest ever reported through the FCC’s Network Outage Reporting System, lasting an hour and a half and impacting approximately 29.4 million interconnected VoIP users and 2.3 million wireless users by blocking approximately 111 million calls nationwide, with over 109 million calls blocked on Level 3’s interconnected VoIP and wireless networks. Calls to 911 from 15 telephone numbers were blocked, and 117 public safety answering points nationwide were unable to receive caller location information. The outage also affected Verizon and West Safety Services. A technician making changes in the anti-fraud network management software, which controls soft switches and gateways, caused the outage by improperly leaving an entry field blank. The software interpreted the blank field as an instruction to block all calls across Level 3’s network rather than only potentially malicious calls. Within minutes, Level 3 received traffic alerts and began resolving the issue. Level 3 has since taken corrective action to prevent future outages including limiting personnel access to software and employing a network provisioning system that allows anti-fraud measures without affecting live traffic.
