How a dumb software glitch kept thousands from reaching 911 [telecom]

It's not that 911 can't be routed through "VoIP". E911 is a service, and different technologies can be used to deliver it. But the FCC doesn't know what "VoIP" is, uses the term loosely, and doesn't want to deal with the difficult questions about the nature of the network and the nature of their rules that it raises. The ILECs, especially ATT, use 911 as a competitive weapon, configuring it in such a manner that other carriers need to jump through expensive ATT hoops to meet the requirements. Companies like Intrado perform a useful service by simplifying access. Software bugs happen; E911 systems however should be built to a standard of reliability that we rarely see nowadays.