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May 11, 2022

Handset-derived location for US and EU Emergency Services 

Over 70% of emergency calls in the EU come from a mobile device, in the US it’s approximately 80%,. With telecommunications and the digital landscape evolving so quickly our Emergency Services are trying to do the same, but it’s important to acknowledge they are not succeeding as well as is needed. 

Issues providing reliable and accurate mobile caller location, and also correctly routing the call to the correct PSAP, remain top of most Emergency Number Networks wish lists, and literally tens of thousands of lives around the globe would be saved if these 2 issues were resolved:

[“The FCC looked at how many 9-1-1 calls for ambulances resulted in deaths that could have been prevented by a one-minute reduction in response time…the FCC estimated more than 10,000 lives a year could be saved by improving 9-1-1 location accuracy.”] 

[“A study by the Alliance for Telecommunication Industry Solutions estimated that an average of 12% of wireless calls are misrouted nationwide.... This equation estimates that more than 16,000 lives could be saved by eliminating misroutes altogether…”]

How is mobile location currently determined?

In Europe, North America, and most other countries globally, irrespective of your telecommunications/ISP network, handset/smart watch, APP or OS, ALL mobile caller location is determined using a version of “Handset Derived Location” utilizing standard location methods and supplemental ones, with combinations thereof.

When a caller dials Emergency Services, the phone, irrespective of being wireless or a landline, doesn’t automatically know where it is or automatically provide its location to the call taker. Instead, once 112/9-1-1 is dialed background technology takes over to search for the location quickly. For mobile, that source of location data comes from the telecommunications network, using cell tower triangulation. Additional to this information, the handset also collects GPS/GNSS data, and any close-by Wi-Fi access point data for an indoor location component. This “gathered and merged” location detail provides the “estimated location with a search area” of the handset. It’s irrelevant which provider is collecting the data, whether it’s an app, Operating System, or protocol, they’re effectively all drawing from the same location data well.

Location accuracy of these emergency calls varies widely and is always on the horizontal plane (ground-level) best quoted as a location estimate with a search area.  

For rural settings GPS and cell-tower triangulation provide relatively accurate latitudinal and longitudinal handset location, but are significantly less accurate in dense city landscapes where buildings stand close together. For indoor emergency calls, GPS and cell tower triangulation offer little-to-no visibility. 

Wi-Fi is typically used for the urban and indoor component, but multipath Wi-Fi distortion (fig1) and crowd-sourcing of vast amounts of data means this information can be unverified, distorted, non-authoritative and “noisy”. Additionally when any handset is not ‘connected’, its Media Access Control (MAC) address can change (or be “randomized”) to comply with privacy policies, meaning the location data harvested isn’t that reliable. 

Fig 1. Wi-Fi distortion representation

Wi-Fi also still provides zero vertical reference to the call. So, if you’re in a multi-storey building on the 15 floor you’re represented as being on the ground floor. You may think this makes little difference, but when seconds and minutes count, Responders searching a building for a victim can lead to tragic outcomes. News outlets back in 2020 covered a story in New York where the unthinkable happened:

Fig 2. Feb 2020. Troy, New York, 45 min search. The 9-1-1 system provided only a general location.

Five officers and 3 firefighters searched each floor but could not locate his apartment.

[“Emergency dispatch systems still struggle to deliver the precise location of cellphone users a quarter-century after the devices became commonplace. The system was only able to provide a general location on Sixth Avenue, which included two five-story apartment buildings”] - Daily Mail, Feb 2020

Then there’s “Reverse Geocoding” which converts geographical location coordinates (i.e., GPS latitude, longitude) to a human-readable address or place name. This component of mobile location-based services aims to make location more easily understood, but it’s not necessarily any more accurate than other location methodologies. 

Since handset location is in itself prone to levels of “error” the subsequent reverse geocode of that data is also prone. And once that geocode has been converted into a potential street address it further requires validation or verification, delivered in real-time at the same time as the emergency call.

Additional to the main location technologies, handsets and networks can also use phone sensor data, such as barometric pressure readings, or device language, to add more information to the emergency call. But there are inconsistencies in barometric data and the z-axis being supplied is being relayed in an unusable format to be helpful for Responders (and it’s still not considered dispatchable) . 

Overall, supplemental location data provided by Big Data is offered on a “best-effort” basis and free of charge to 9-1-1. But it’s important to distinguish that whilst this information is important to assist emergency calls, companies such as Apple Inc (HELO and EED location) clearly state they provide and estimated location with a search area and do not provide what our industry refers to as DISPATCHABLE ADDRESS:

“Q. Does EED provide a civic or “dispatchable” address?

A. No. EED provides a high-accuracy, high-integrity geodetic or “latitude /longitude / uncertainty” location estimate. All practical location estimation technologies, including HELO, estimate user location by measuring noisy real-world signals. Estimates based on such measurements are limited in their accuracy and precision.” 

You can appreciate there is a lot of information being shared during these emergency calls, but ultimately, it’s the quality of that data, not the quantity which matters, offering in many cases no dispatchable address…the industry gold standard.

The FCC in the US adapted the Ray Baum Act for improved location to mobile calls, allowing carriers to provide z-axis OR dispatchable information for an emergency mobile call. This caused some concern:

FCC Commissioner Jessica Rosenworcel dissented in part, noting that the height-above-ellipsoid (HAE) format that the carriers must use to deliver vertical-location information is not useful to public safety.

“There is not one 911 call center today that can take the raw numbers in height above ellipsoid and translate them into actionable dispatchable-location information,” Rosenworcel said during a press conference following the FCC open meeting. “If we acted in this room today like the job is done, then we lied to you. And I’m afraid our decision was dishonest about whether the information is actionable.

“The fact so many 911 operators wrote into the agency and wrote to my office, telling me they were distressed that we would organize around information they could not use, I think is a testament to the fact that … we have a lot more work to do.”

Obtaining a Dispatchable location is perceived as being complicated, requiring collaboration across an industry, with concerns around interoperability, privacy, and cybersecurity, and it’s true, it does look complicated, but is it really? And does that mean we should just give up?

“It’s not that I’m so smart, it’s just that I stay with problems longer.”– Albert Einstein