Someone else pointed out that if the system in question has been botted/owned/pwn3d/whatever you want to call it, then, you can't guarantee it would make the 911 call correctly anyway.
I realize that many NANOG'ers don't actually use the technologies that we talk about, so I'm just going to correct this: You seem to be under the mistaken assumption that most people using VoIP do so using their computer. While it kind of started out that way years ago, it simply isn't so anymore. Most VoIP services can be configured to work with an analog telephony adapter, providing a POTS jack. Most VoIP services even provide one as part of the subscription, sometimes for a fee. There's also a growing number of phones that support Skype or generic VoIP, sometimes alongside a regular POTS line, sometimes not. It is perfectly possible to have an infected PC sitting right next to a nice VoIP-capable DECT cordless phone system, both hooked to the same NAT router. This is, of course, problematic, and would be a useful problem to contemplate how to cause one to break while keeping the other operational. Assuming that the existence of an infected PC in the mix translates to some sort of inability to make a 911 call correctly is, however, simply irresponsible, and at some point, is probably asking for trouble. ... JG -- Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net "We call it the 'one bite at the apple' rule. Give me one chance [and] then I won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN) With 24 million small businesses in the US alone, that's way too many apples.