Outgoing calls from phone-centric providers (Vonage, et al) come with the service package, because they emulate traditional telephones. People expect any traditional telephone they pick up to reach any number they wish to dial, which the phones do, even if the first leg of the trip runs over a broadband cable instead of telephone wires.
However, behind the scenes, the telephone network evolved and continues to function in some bizarre ways. Technical systems built by traditions rather than modern engineering principles include a variety of quirky features and downright weird processes, and the traditional telephone network carries their bizarre process banner high.
So even though a phone-centric provider lets you pick up a phone and dial Aunt Martha, reaching a 911 operator starts an entirely different (weird) process. Those of you with monitored alarm systems may also need to take a couple of extra steps.
911 calls will be an issue for phone-centric providers for the next couple of years, but this wouldn’t be a big problem if the broadband phone companies had planned better. Government committees are looking into the problem now, which will likely muddy rather than clarify the issue.
Computer-centric phones involve an entirely different set of problems and will lag far behind for years and years. Those of you with softphones who want to call 911 from your PDA may not reach that goal for another 10 years. OK, maybe five years.