“The firewall prevented calls from getting to the 911 dispatch centers, also known as Public Safety Answer Points (PSAPs).”
Massachusetts lost statewide 911 for about two hours, and the cause was a firewall its vendor Comtech installed to keep hackers out. No attacker needed to show up. Comtech still can’t say why the firewall blocked the calls, but promises it won’t happen again. The state’s fallback was dispatchers calling back the numbers that failed to get through.