Wireless coverage area from a typical cell sector.

In its Second Report and Order dated Sept. 23, 2010, the FCC adopted new rules governing the accuracy of location information provided by wireless carriers to PSAPs.[1] There’s much good news in this order. One of the best aspects will require accuracy measurements from the county or PSAP geographic level. Prior to this, carriers had said they wanted to average accuracy levels over larger regional areas. In these cases, large cities where carriers could supply high-accuracy levels would skew the results for rural counties.

Not all the news is good, however. The standards allow for different time frames for compliance, depending on whether the carrier uses network- or handset-based location technology.

At the end of eight years, handsets that rely on GPS technology must ensure that 67% of Phase II calls are accurate to within 50 meters, and 90% of Phase II calls are accurate to within 150 meters in all counties or PSAP service areas.

Network-based carriers must ensure that 67% of Phase II calls are accurate to within 100 meters in all counties or PSAP service areas, and 90% of Phase II calls are accurate to within 300 meters in 85% of counties or PSAP service areas. 

Big downside: Carriers using handset-based technologies can exclude up to 15% of counties based on the inability to get a reliable signal due to heavy forestation. Carriers using network-based technologies may exclude counties or portions of counties where triangulation isn’t technically possible.

The FCC ordered that confidence and uncertainty data be provided on a per call basis upon PSAP request beginning at the end of year two to allow for PSAP testing. APCO International argued that emergency responders needed to know what to do when they arrive on scene but can’t see the emergency. If the call were delivered with a high degree of accuracy, the search for the actual incident would be narrowed. Conversely, if the accuracy level is low, a wider search area would be required.

Waiting eight years for accuracy standards that can only reliably tell a PSAP that someone is calling for help within 300 meters 90% of the time may appear strange when it seems Google maps can pinpoint us every time right now. For those readers who might be metrically challenged, 300 meters is 984 feet. In other words, a person in trouble could be more than three football fields away from the location sent to the PSAP. To find a caller in a rural county at these distance standards would be challenging. In a downtown of a large city, they might be virtually useless.

If you are a PSAP director, do you have little choice but to wait for the FCC deadlines and hope for the best from the wireless carriers? Are there things you can and should do now to improve the accuracy of wireless calls for the citizens of your county?

In fact, there are counties working now to improve the wireless call data quality coming into their PSAPs. They aren’t waiting for the FCC’s deadlines, and you don’t have to either.

How Many Calls …
Every PSAP director knows the answer to this question: How many E9-1-1 calls does it take to put you and your PSAP on the front page of your county’s newspapers? Of course, the answer is just one.

The ability of any PSAP to serve the needs of its citizens largely relies on the quality of data the PSAP can accumulate. How many hours are spent just to ensure addresses are valid? How much time is spent making sure all the files in the dispatch systems are correct, including the geofile, code tables, vehicle and personnel lists, premise histories, geographic boundary tables, etc.? If the geofile is wrong, the CAD won’t recognize an address, and, thus, an emergency response to a citizen will be delayed. If a geographic boundary is incorrect, an incident might be dispatched to the wrong first responder.

Data quality has to be one of the major duties of any PSAP. Why? Because good data quality equals good E9-1-1 response and that equals lives saved.

According to statistics compiled by NENA, an estimated 240 million E9-1-1 calls are made each year in the U.S.2 The FCC estimates that one-third of these calls are wireless.[2] In larger communities, the wireless call volume may be more than 50%, with some communities experiencing volumes as high as 70%. The upward trend shows no sign of slowing as more citizens abandon their wireline phones.

The question then is: If ensuring data quality is the responsibility of any PSAP, how can a PSAP director ignore the quality of data received from the wireless network through which most of their customers seek help? You can’t.

Project LOCATE
APCO has been on the forefront of educating the public and PSAPs about the evolution of wireless location technology. In 2007, APCO issued a report titled, An Assessment of the Value of Location Data Delivered to PSAPs with Enhanced Wireless 911 Calls.[3] Recognizing that “every PSAP should seek to assess the actual performance of the current systems and assist consumers within the service area, to best utilize their wireless E9-1-1 access in times of crisis,” APCO worked with a number of PSAPs to field test the accuracy of the wireless data they were receiving.

As a supplement to this project, in January 2008, APCO issued a report titled, Project LOCATE, Wireless 9-1-1 Deployment and Management Effective Practices Guide.[4] The guide included a number of excellent practices that should be followed to improve the quality of wireless data coming to PSAPs.

One key observation in the report is worth noting: Both E9-1-1 callers and first responders have come to expect that the location received by the PSAP is always correct. Years of work improving the location data from wireline calls has led many to believe the same accuracy exists on the wireless side. Although education and training will help in this area, the perception that the Phase II information is always correct still persists.

Improving Quality Today
Map the wireless infrastructure: Although this may seem to be a strange first step, understanding where wireless infrastructure is located within your county and how it works is extremely important.

What will happen if a major cell site, one that carries a great deal of wireless calls, goes down? Your calls may be routed to another PSAP. What happens if the carrier’s switch goes down? Calls normally designated for your county PSAP could be shipped to another PSAP designated by the carrier, one that may be in another state. You would never know this or be able to mitigate the impact of the loss of that site or switch unless you understand more about the network that handles your E9-1-1 calls.

Another benefit to knowing where the wireless infrastructure is located will be in interference mitigation. Many public safety agencies have moved into the

800 MHz band, and there is widespread belief that the FCC mandate for rebanding will solve all the interference being experienced by public safety. Those who have already rebanded and are still mitigating interference from wireless carriers know the problems may be decreased with one carrier, but they have not totally disappeared. Knowing where all the potential wireless carriers are located will, in many cases, make mitigation much easier.

Working with the Carriers
The APCO reports mentioned above stressed the importance of working with carriers. “APCO, on behalf of public safety, recognizes that working in partnership with the WSPs is the appropriate path and, in most cases, avoid[s] what could become a steady stream of complaints to the Wireless Enforcement Bureau of the FCC.”[3]

Wireless carriers have been extremely cooperative in working with public safety when called upon to do so, but the county has to be proactive. Carriers aren’t coming to you and asking if you will check the quality of their data.

Some counties have not only mapped the current wireless carrier locations, but they are requiring carriers to test new locations as they are built. Carriers will tell you they are testing their new tower locations, but their tests won’t be as stringent as yours will be.

What’s testing going to tell you? The most important thing to test is whether the PSAP is getting the correct location information from wireless callers from the new tower location. Although the FCC mandates might not apply yet, many carriers want to ensure their customers are routed to the correct E9-1-1 center and the location information is as accurate as they can make it.

Another piece of data coming from some wireless carriers is a level of uncertainty. In other words, how sure is the carrier that the caller is actually standing at the location received by the E9-1-1 calltaker. In January 2013, carriers must pass this information to the PSAP on request. By collecting this information now, PSAP directors can trend the data and ascertain if it’s getting better or worse as time goes by.

When a PSAP is notified of a new cellular site, often the carrier will send the routing sheets to the PSAP and the PSAP will approve them based on the information received from the carrier. In many of these cases, the routing is never really examined after the site is turned on. Calls that hit a cell site sector are all sent to one PSAP. After the site is turned on, an analysis of the traffic might reveal that most wireless calls hitting one tower sector should really be going to the adjoining PSAP. This means until the problem is corrected, your PSAP might be transferring an inordinate amount of calls. If you were aware of this issue, you could have the carrier just change the routing and ensure most of the calls go to the correct PSAP in the first place.

Analyzing call data on a continuing basis will point out errors in the phone records received at the PSAP and assist in cleaning up all data over time.

Wireless Data
When PSAP directors think of wireless data, they tend to think of customer name, ANI, ALI, latitude and longitude. Actually, much more data may be contained in the wireless record.

Some carriers are already sending information on the tower location, location accuracy estimates, whether a call is Phase 1 or Phase 2, community name, state designator, ESRK/ESRD number, company ID and trunk number.

The ESRD (Emergency Services Routing Digit)/ESRK (Emergency Services Routing Key) numbers are used for routing a wireless call to the correct PSAP. The ESRD identifies the cell site and cell sector of the call origination. The ESRK uniquely identifies the call in a given cell site and cell sector, and correlates data provided to the PSAP from different paths, such as the voice and ALI paths.

In the absence of an exact location in an emergency, knowing the wireless caller called from within a certain area covered by a cell sector might be better than knowing nothing at all.

Phone Traffic Analysis
Many PSAPs have done phone traffic studies over the years. Many of these studies are geared to ensuring the phone companies are billing correctly. But as one can see from all the available data, there is much more to be gleaned from information received from the E9-1-1 call itself. Even when studies are done, they tend to look at a subset of E9-1-1 calls and make assumptions about all the calls from that single subset. There’s a much better way. Why not look at all the calls?

Analyzing your PSAP phone call traffic on an ongoing basis has a number of distinct advantages, the first one being early notification. Today, PSAPs are the first to know that an emergency is occurring. They also are the first to determine the size and scope of an unfolding emergency. In a large PSAP where many calltakers might be answering calls for the same incident, the fact that an emergency exists may not be discerned until the calltakers start coding the individual calls and a pattern emerges. The pattern might be spotted by a dispatcher or a supervisor. The pattern may appear on a map or in a dispatch queue. But to see the pattern, you’d have to wait until the call was coded and entered to the CAD.

What if you could see an emerging pattern through the number and geographic distribution of just the phone calls coming to the PSAP? For especially large incidents that generate significant numbers of calls, pulling information directly from the phone switch can show a pattern minutes before the CAD does.

Analyzing calls as they come in:

• Permits the E9-1-1 calltaker to know if a phone call is made geographically far from the incident being reported. This is a trick sometimes used by burglars or thieves to lure the police away from a certain area;
• Can provide information about whether a call is coming from a non-initialized phone (Note: A non-initialized phone is one which doesn’t have service from a carrier but is able to make E9-1-1 calls. Non-initialized phones are a source of many fraudulent calls.);
• Shows patterns with abandoned calls by date, time, etc.;
• Can be “timer specific” by carrier as to when an E9-1-1 calltaker should rebid a wireless call; these rebid times may differ by carrier;
• Provides notification about when a wireless caller’s location might be beyond the limits set forth by the FCC rules; and
• Alert the calltaker to wireless calls going to other than the closest carrier site: Calls may be routed to the wrong PSAP or be routed to the correct PSAP, but could be overloading an already busy site instead of the one closest to the call.

Other benefits: If a county or city has a camera system, a phone call from a certain location can be used to turn a camera on or call the attention of a supervisor to watch a certain camera. Cameras might also be turned on based on a threshold of calls received from a certain geographic area. And a call received from outside the PSAP area of jurisdiction could alert the E9-1-1 calltaker where to transfer the call.

Of course, once call data is collected and analyzed, all types of off-line reports are possible:

• Number of abandoned calls per month;
• What area of the county has the most abandoned calls;
• Time of day/day of week studies;
• Number of calls that came from outside the PSAP area had to be transferred by your calltakers; and
• Which carriers are sending these calls.

If history is any teacher, here are some issues you’ll see:

• Wireless and VoIP calls with no ANI or ALI;
• Calls with no location information;
• Calls with no latitude or longitude;
• Calls with no cell sector or carrier information; and
• More Phase 1 calls than you thought, especially if you think you’re Phase II compliant.

What Will the Carriers Do?
Although it varies by carrier, generally cooperation is good in fixing these problems once they are identified. By constantly monitoring your PSAP’s phone traffic, over time you’ll correct these issues and improve the data quality of the phone records coming to your PSAP. One of the byproducts of this is an improvement in the accuracy of information you’ll receive on wireless callers to your center.

Conclusion
An effective emergency response largely depends on accurate data. With cell phones becoming the overwhelming method citizens use to call 9-1-1, a renewed focus must be placed on improving the accuracy of the wireless data the PSAP receives from the carriers. By taking the same care and effort used to ensure the data quality of your other E9-1-1 systems, you can be better assured that the story on the front page won’t be about you and what you could have done to save someone’s life.

About the Author
Charles Brennan is vice president of Essential Management Solutions LLC (www.emsolutionsllc.net), based in Pennsylvania, and a former deputy police commissioner with the Philadelphia Police Department, having served there for 33 years. He ran the department’s PSAP for almost 10 years. Contact him at cjb@emsolutionsllc.net.

References

1.            Wireless 9-1-1 Location Accuracy Requirements, PS Docket 07-114, Second Report and Order, FCC 10-176, 25 FCC Rcd 18909 (2010).
2.            National Emergency Number Association (May 2011). 911 Statistics. Retrieved June 2011, from www.nena.org/911-statistics.
3.            APCO International Project LOCATE Team. Final report: An assessment of the value of location data delivered to PSAPs with enhanced wireless 911 calls. April 2007.
4.            APCO International Project LOCATE Team. Wireless 9-1-1 deployment and management effective practices guide. January 2008.

Originally published in Public Safety Communications magazine, Vol. 77(8):68-76, August 2011.