Well, this is not only a fictitious scenario that happened in Massachusetts in USA. (One of the states of USA with a population of almost 7 million.) The 911 Department of the state was unreachable for 2 hours because of a safety feature on a firewall which was supposed to provide protection against cyber attacks and hacking. Actually, it seems to be that the feature was successful to prevent cyberattacks, as well as legitimate users.
An additional firewall feature can enhance your confidentiality but can also have a crippling effect on your availability in your system. (Remember AIC triangle.) You have to be more than careful if you are working with the critical structures of a region. Money costs can be affordable but life costs CANNOT.
"On June 18, 2024, at approximately 1:15 pm, the Massachusetts State 911 Department became aware of a statewide interruption to the 911 system. The disruption lasted approximately two hours until operation was fully restored at 3:15 pm."
"A preliminary investigation conducted by the State 911 Department and Comtech determined that the outage was the result of a firewall, a safety feature that provides protection against cyberattacks and hacking. The firewall prevented calls from getting to the 911 dispatch centers, also known as Public Safety Answer Points (PSAPs). Comtech’s initial review of the incident has confirmed that the interruption was not the result of a cyberattack or hack; However, the exact reason the firewall stopped calls from reaching dispatch centers remains under review."
"In 2023, Massachusetts’ 204 Public Safety Answering Points received a total average of 8,800 calls a day."
