[Asterisk-Users] RE:911, networks of * servers, etc. (was: VOIP Dialtone?)

[Michael Kane]

There are TDM interfaces higher end PBX's use to interconnect to the PS/ALI.
I beleive it's a CAMA trunk that signals using MF.



----- Original Message -----
From: "John Todd" <jtodd at loligo.com>
To: <asterisk-users at lists.digium.com>
Sent: Thursday, August 21, 2003 3:00 PM
Subject: [Asterisk-Users] RE:911, networks of * servers, etc. (was: VOIP
Dialtone?)


>
> Yes, I'm familiar with the E911 platforms and their requirements to
> some degree.  The trick is that the people running Asterisk PBX
> systems have no visibility into SS7, and that is an unreasonable
> expectation, so some other out-of-band method for moving caller
> location to the PSAP is required.
>
> As far as geographic location tracking is concerned: that is the
> user's problem.  If they don't have the correct information in their
> device, then they're SOL.  There is _no way_ to develop lat/lon/alt
> coordinates from an IP address, despite what any .com
> flash-in-the-pan company says they can do with their clever
> databases.  Thus, the PBX/switch provider will have to enforce their
> own database of device-to-geographic-coordinates.  (As mentioned,
> maybe a SIP header is a reasonable thing to use for the UA to relay
> this data to the proxy.)  I am not concerned so much about the
> ability of the devices to send their data to the proxy: I am VERY
> concerned about how the proxy then looks up the appropriate PSAP, and
> then relays the data for the call to that PSAP.
>
> JT
>
>
>
>
> >911 through the phone system is tricky business. e911 which is the
> >automated process of handing the address to the 911 center uses the SS7
> >database to do it's work (the database is created when the LEC runs
> >physical lines to locations not by people filling anything out). Cell
phone
> >service providers have the simuliar problems as VoIP service providers
are
> >facing are realizing with call forwarding and call following it will get
> >worse.. Congress has mandated that the cell phone industry make it
possible
> >to track a cell phone users within 300yards via cell sites and
> >triangulation. By 2005 every cell phone will be required to have a GPS
and
> >send GPS information to the 911 system when they call 911. If you want
more
> >information on e911 try http://www.fcc.gov/911/enhanced/ . As the cell
> >phone industry grows there will be a need for a national 911 call routing
> >center. I bet it won't be free.
> >
> >
> >Original Message:
> >-----------------
> >From: John Todd jtodd at loligo.com
> >Date: Thu, 21 Aug 2003 01:32:24 -0700
> >To: asterisk-users at lists.digium.com
> >Subject: [Asterisk-Users] 911, networks of * servers, etc. (was: VOIP
> >Dialtone?)
> >
> >
> >
> >OK, that "VOIP dialtone?" thread was getting really out of hand, so
> >I'll condense my answers into one big ugly message:
> >
> >
> >1) 911 service.  Yes, that is one of three reasons to keep your PSTN
> >line.  The other two reasons are:   Inbound calls from local callers
> >still should work on a POTS line, for now.  You can't find VOIP
> >providers in most area codes, so you'll most likely need to have a
> >"local" number that finds it's way to you for "local" tasks.
> >Secondly, the Internet is not as reliable as the phone system.
> >Sorry, folks, it just works that way right now despite what your
> >network engineer might tell you.  That's not to say it's unreliable,
> >but those last two nines are very expensive... Besides, any good
> >network engineer will tell you that you should have multiple paths
> >for your IP connectivity.  With few exceptions, most homes do not
> >have multipath connectivity.  (note: businesses may in fact have
> >better uptime on their IP network than their phone network, if they
> >have competent engineers and a reasonable budget.)
> >
> >1.5) There are reasonable technical solutions to this problem, but
> >for the life of me I can't figure out why the 911 centers haven't
> >gotten their act together and solved this.  There are two halves to
> >this problem: "What PSAP do I call? (and what phone number)"  and
> >"How do I get my location data to the PSAP once I call them?"
> >C'mon, this is not difficult.  The first question can be answered
> >trivially: there _must_ be a database of address-to-PSAP mappings.
> >Any PBX administrator (or SIP phone owner, for that matter) should be
> >able to figure out their address.  Methods for associating the PSAP
> >number with the phone are numerous, and trivially implemented - if
> >people don't keep their address information updated, they're SOL
> >(though you can remind them in an automated fashion to keep it
> >updated - just forbid them from using the service unless they verify
> >the address every month or so.)
> >
> >The second question is more difficult, but certainly possible.  There
> >may be kludge ways of doing it, and there should be more elegant ways
> >of doing it.  A SIP header with lat/lon/alt data that gets sent from
> >the UA only on 911 (or other programmable string) calls might be
> >reasonably elegant... maybe.  But that only gets the data to the SIP
> >proxy.  That doesn't solve the issue of how you get that data from
> >the SIP proxy to the PSAP, which at some point will be almost
> >certainly through a PSTN connection... ADSI FSK, maybe?  Ugly, and
> >PSAPs would not want to invest in equipment.  A national caller-id to
> >location clearinghouse in which your proxy could participate (any 911
> >calls would create a temporary mapping)?  Maybe, but probably not.
> >Non-standard, and I doubt PSAP operators would want another tool,
> >even if it is web-based and so easy a monkey could use it.  I don't
> >know.  I guess I'll grill the PSAP people at the panel next month at
> >VON.  :-)
> >
> [snip]
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