911 operators couldn't trace the location [telecom]

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 > 911 operators couldn't trace the location of a dying student's phone.
 > It's a growing issue.

Is it?

I read this piece of YKW* and immediately wondered who her source was,  
and why she wrote it. It's clearly not in her subject expertise.


The FCC has imposed location requirements on the carriers, and that  
costs them money. They can not now depend on GPS for several reasons:

a) It does not always work indoors.

b) It does not provide the PSAP with the floor or room.

c) Being a significant power drain, users often have GPS turned off.
(Is there anyone out there saying "My phone lasts too long without a  

d) User may want it off, given the propensity of the carriers to exploit  
location data for their purposes; i.e. sell users locations to advertisers.

e) Not all phones have GPS. Can you think of a flip phone or candy bar  
phone that does?

So my first guess is a carrier lobbyist sold the reporter on it. If only  
they could depend on user's GPS, they don't need expensive timing  
methods. And if it fails, shrug.. "We tried!"

My second guess was it was the FBI. We know how they feel about anyone  
doing something on a phone without their knowing all about it. (Just ask  
Tim Cook!)

Could this be the precursor for mandatory GPS use? Or a "fix" so the FBI  
can enable your GPS remotely? Donno...

***** Moderator's Note *****

* In this context, I think "YKW" means "You Know What."

I didn't know that the GPS in a cell phone could be disabled. When did
that start? Who can do it?

Why do you say "It does not provide the PSAP with the floor or room?"
I though GPS could repost altitude, and that "GPS-enabled smartphones
are typically accurate to within a 4.9 m (16 ft.) radius under open
sky."(1) Isn't that enough to get to a single floor in one building?  

Bill Horne

1. https://www.gps.gov/systems/gps/performance/accuracy/

Re: 911 operators couldn't trace the location [telecom]

Telecom Digest Moderator wrote:
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On any smartphone I've seen, GPS is an easily controlled setting.
Android usually says "Location" on the settings menu.

Quoted text here. Click to load it

Often no. You need at least 3 satellites to get a Lat/Long fix. But
altitude is far harder to get close; more birds are needed to do so.
Open air easily gets you >>3 satellites. But inside a building is
harder. Plus you have the issue of how long it takes to get an initial
GPS fix. That can be up to 12 minutes.

Suppose you are in the windowless core of a building. You may be under
a cell on the roof, or the next building has one. Or the building has
a cell repeater. The GPS birds are at the best 12,000 miles above you
and far far weaker. Slant range birds will be further away but you
need those birds to get a GPS lock; the further they are, the more
accurate the fix will be.

The carriers may use Augmented GPS  
<https://en.wikipedia.org/wiki/Assisted_GPS as one helper.

A further complication: Many smartphones/carriers allow calls over
WiFi when it is available and cell coverage is weak/saturated. The
carriers must love that -- a WiFi call does not tie up any of their
expensive RF resources; instead the user/building provides the TCP/IP
bandwidth to the carrier. (Note: If you are on a per-minute cell plan,
the nice carrier likely *still* charges you on WiFi calls.) I have no
idea what address data the carrier passes to the PSAP (Public Service
Answering Point) in such a case. But consider being on a huge campus
network such as the GooglePlex or Ohio State University.

(All of this is why I got my nephew with a small child a VOIP account
and a Western Electric 2500 set for their house, and confirmed the
registered dispatch address is correct.)

Now sometimes the carriers sell you picocells you plug into your home
Internet feed. They are designed to only initially register after the
GPS inside the picocell has a lock; thereafter it CAN tell the PSAP
the caller is within its tiny range.

I suspect the article came from recent legislation; as of this month,
Sec 506 of Ray Baum's Act requires the PSAP get the "dispatchable
location" of a 911 call. That means address, floor, room #. Plus, the
911 call must also tell the front desk/security office of the call. (I
assume that's so the responders can be escorted to the caller's room.)
Most PBX systems now in use can not do this.

In summary:

1) Not all calls provide GPS data
2) The carriers are required to provide a "dispatchable location."
3) How?

Re: 911 operators couldn't trace the location [telecom]
On Tuesday, February 25, 2020 at 10:24:20 PM UTC-5, Telecom Digest Moderator wrote:

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On my plain cell phone, I may disable the GPS so that other people may
not see where I am.  However, I cannot disable it to prevent the cops
from tracking me.

I should note that for cops to be able to track someone's cell phone
location, they need to have upgraded equipment to do so.  Not all
departments invested the money to do this.

My feeling is that if someone is in any kind of trouble needing 911
help, they should attempt if at all possible, to know as much as their
specific location to pass it along to the 911 operator.  Hopefully
other people would be around who could provide assistance, especially
in a large building.

Some large organizations have trained their security staff on how to
handle 911 emergencies, such [as] having doors wide open, having
elevators on standby, and directing rescue personnel to the specific
spot to save time.  Big help.  But not all places do this.

One frustration is that some areas have consolidated their 911 call
centers, so they now serve a large geographic area.  That means the
operator might not be familiar with a particular shopping center or a
residential street name that may be duplicated from one development to
another.  Computers are supposed to keep this all straight, but
sometimes the programming or data isn't adequate or the caller can't
help.  "I'm at the McDonald's on Rt 100" won't be enough if there five
McDonald's along the full length of Rt 100.


Re: 911 operators couldn't trace the location [telecom]
On 2/26/20 08:45, David wrote:

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The other issue, particularly in urban areas, is multipath. As GPS  
depends on measuring time-in-flight, reflections from nearby buildings  
and within a building will severely reduce accuracy. You can see this in  
vehicles with GPS mapping systems. In urban areas with tall buildings it  
isn't uncommon to see errors of a city block or more.

Re: 911 operators couldn't trace the location [telecom]

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My gravel road starts on a major highway, wanders 3 miles into the
woods, then 2.5 miles back to a secondary paved road.  The secondary
paved road connects to the major highway a mile closer to "town" than
the other end of my gravel road.  I live half a mile from the
secondary paved road and that half mile is the only part of my road
that is well maintained.

The only time in 50 years that I've had to call for an ambulance, the
GPS directed them to the end of my road that connects to the major
highway.  So they had to thrash 5 miles over icy frozen ruts to reach
me.  They could have used the secondary paved road route for a total
of 3 fewer miles, none of it over poorly maintained surface.

So the location (911 via land line) worked perfectly but the routing
was problematic.

The fire department is local volunteer who would know the best route.
Emergency medical is staffed from a wide area and dispatched from the
local market town 13 miles away.

Just an anecdotal data point,

Mike Spencer                  Nova Scotia, Canada

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