At 11:21 AM +0100 2005-07-20, [EMAIL PROTECTED] wrote:
On the other hand, maybe all you want to do is to route the
call to the right E911 center. In that case, as long as you
are in the right county you are probably OK.
If all you use the "last known position" information for is
routing to the correct E911 system, that might be okay. However, one
thing I believe you need to also transmit along with the position
information is "time since last fix", so that you can get some sort
of idea how long it's been since that position information was
reasonably accurate.
If the time since last fix is several hours, then the person
might now be on a plane using a picocell or broadband wireless
network connection that is not position-enhanced, and using the
position information for routing to the presumed correct E911 system
may be inappropriate.
So long as we give additional information which gives the system
an idea of the expected level of age and error in the information, I
think the risks should be able to be reasonably minimized.
In any case, no solution to E911 and VoIP is likely to meet
100% of its requirements, but if you can improve the situation
significantly, then it is still worth doing.
I guess it also depends on what you mean by "significantly". Is
a 10% solution significant? Do you need 90% before you're
significant? And what's the cost of false positives, as well as
false negatives? I think all these factors need to be considered,
when looking at potential solutions.
--
Brad Knowles, <[EMAIL PROTECTED]>
"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."
-- Benjamin Franklin (1706-1790), reply of the Pennsylvania
Assembly to the Governor, November 11, 1755
SAGE member since 1995. See <http://www.sage.org/> for more info.
