The Federal Bureau of Investigation (FBI) has warned of the consequences of telephony denial-of-service (TDoS) attacks. The FBI published this warning on Wednesday as an IC3 public service announcement and as a Private Industry Notification issued to private sector organizations in coordination with DHS-CISA. TDoS attacks are manual or automated malicious attempts to render telephone systems unavailable by blocking incoming and outgoing calls. They’ve also been used in the past to disrupt emergency services from answering emergency calls for legitimate requests for help.
Source: https://www.bleepingcomputer.com/news/security/fbi-telephony-denial-of-service-attacks-can-lead-to-loss-of-lives/