Since its inception in the late 60’s and wide-spread deployment in the 80’s we have all come to take 911 for granted. No matter where you are in the US, if you dial 911 you expect to be connected to an emergency center for police and fire service.
All telephone providers in the US are required by FCC rules to connect a caller to the proper 911 center based upon their location. These 911 centers are referred to as Public Safety Answering Points (PSAPs). The PSAPs are operated by counties, cities or regionally. PSAPs vary in sophistication from large 911 centers in major cities that have hundreds of operators, to small rural 911 systems where the calls get routed to the local sheriff’s office and involve almost no technology.
I have recently seen two different sets of headlines that put 911 back in the news. The first was about the emergence of text-to-911, where texting to 911 will connect you to the closest PSAP. This grew out of the movement to create next generation 911, which has the goal of allowing voice, text or video emergency calls from any communications device using IP. Historically 911 has been limited to voice calls made from landline or cellphones, except for calls made by deaf and hearing-impaired people using teletypes and other similar devices.
In 2013 the largest wireless carriers began testing text 911 with some large urban PSAPs. People can text 911 and be connected to their PSAP, which will then respond to them via text. The genesis of this upgrade is to provide 911 from anywhere for the hearing-impaired, who can only now do this using special devices. But texting to 911 would be available to anybody
The FCC issued a policy statement in January of this year that said that every wireless carrier should provide text-to-911 service, although it is not yet mandatory. The FCC also mandated that the wireless carriers send back a ‘bounce-back’ message to the sender if they are unable to complete the call to a PSAP. Without that return message a person would assume that the text message successfully got to 911. Both the FCC and the PSAPs encourage people to make the call by voice whenever possible and only use text when there is no other alternative.
There was also some recent more disturbing news about 911. The FCC recently released data that showed that in 2013 that 90% of the 911 calls in Washington DC originated from wireless devices did not deliver the precise location data of the caller. This is a bit chilling for several reasons. First, a large percentage of the population now only uses cell phones, and so this is their only way to call 911. And secondly, not everybody knows their address when they call. If the caller is a child or a tourist they might not have any idea of their location. And sometimes callers who are in danger call 911 and can’t speak and rely on 911 knowing where they are at
Mobile 911 makes a determination of a callers location using triangulation. This means that the 911 PSAP is able to ping back to the cell phone and see the location of several nearby cell towers. By looking at the relative strengths of those ping-backs they were historically able to pinpoint a caller within 50 – 100 feet, often closer.
But this system was established when there was only a handful of cell towers in the world, and so it became fairly easy to locate a caller. But today there is a proliferation of cellular transmitting devices in the network, particularly in urban areas. The cell phone companies are reported to be installing millions of mini-cell sites this year – sites which act as cell towers, but for a much smaller area like part of a stadium, a busy street or on a commuter bridge. Additionally, anybody is able to buy a cell phone booster. These are essentially cellular repeaters with a short range and are used to bring strong outside signals to the inside of a building.
But to a PSAP all of these devices look like enough like cell towers to cause confusion in the triangulation algorithms. And so, where mobile 911 was once fairly accurate, it is now a jumbled mess in urban areas where there is a proliferation of transmitting devices. I am sure there is a technological solution to this, but it is going to take the cell phone carriers start over to find a way to locate a cell phone in an urban environment.
While the headlines of 9 out of 10 being inaccurate sounds scary, the reality is that the lack of precise data didn’t affect most of these calls. Otherwise we’d be seeing a lot of shocking headlines. Remember that in most cases that the 911 PSAP speaks to the caller who can verify their location. And even when the mobile 911 system in not entirely accurate it probably gets close enough to be effective most of the time. But I remember the headlines in the early 80s when several people having heart attacks died because they called 911 from a payphone and didn’t know their location. I hope this latest report prompts the FCC and the cell companies to find a solution before we go back to those headlines again.