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

[Robert Singleton]

On Thu, 2007-08-02 at 14:05 -0500, Robert Kulagowski wrote:
> 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.

<snip>

> 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.

It can be as simple as an FXO on the local router connected to a single
local line at the site. CallManager and SRST will route 911 calls for
that Calling Search Space using that line. The important things to
comply with are that the service address of the number matches the
address that emergency services would be dispatched to and that that
line can answer a call back from the 911 operator.

> 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)

We are doing something similar to this using a service provided by
http://www.dash911.com/ 

We have 71 branches in 21 different area codes, many with two or more
physical addresses. We also have a few partner companies that we are
'subletting' space on our CallManager. In all, there are 97 unique
external phone number masks from which a 911 call can be made. Our setup
involves a SIP trunk to an Asterisk box that does some real time
scripting. A user calls 911 and the call is sent to Asterisk. Asterisk
forwards the call to dash911, who then forwards the call (with the
proper information) to the appropriate PSAP. They require us to be able
to redirect the call to them automatically on busy, no answer, etc (thus
the Asterisk box) and if they cant determine the proper address and info
to send to the PSAP, they have a call center that manually transfers the
call if needed.

Robert