[cisco-voip] Need some facts regarding DID's, Enterprise VoIP and LATAs

[Robert Kulagowski]

If you're going to provide for 911 at each location, then you're going 
to need to get _something_ at that site.  It can be as simple as a 
standard analog line that you connect to a FXO port on a voice gateway, 
with appropriate routing in CM to send a 911 call out from that location.

PSAPs (Public Safety Answering Points) aren't necessarily linked to each 
other, so if someone in Houston is having a heart attack, and all calls 
go out from Dallas, there's nothing much that the PSAP in Dallas can do 
about it.

You don't need to renumber, or give users in your other locations 
numbers "DIDs" in those locations.  Just make sure that a call in 
Houston goes out through Houston, and a call in Dallas goes out through 
Dallas, etc.  Which pretty much means that you're going to need a 
"circuit" at those locations.

One caveat:  you may be able to get someone like one of the E911 VoIP 
service providers involved (www.911enable.com is one); you'd setup 
something like a SIP trunk and route e911 calls to them.  You'd tell 
them which DIDs are located in which city, and allow them to handle the 
911 call and send it to the correct PSAP.  (In which case 911 calls 
wouldn't traverse your PRI - they'd go out over your ethernet to the 
provider)