We’ve all seen it on TV and in movies. A call is made to the police from the bad guy, and they try and keep him on the line long enough to trace the call. There are two issues with this. Firstly, it takes a split second to locate a call that isn’t somehow being deliberately re-routed. Secondly, none of the bad guys ever seem to own a cellphone.
But, if you did call 911 from a cellphone, would the operator know where you are if you can’t speak? The short, and slightly disappointing answer is, no, they wouldn’t. Well, not really.
Back in the early days of mobile phones, lots of people couldn’t get the hang of always using the area code of a phone number. After all, if they were calling the Domino’s up the street from their landline, they didn’t need to. The problem, of course, is that the cell phone is, by nature, a mobile entity. It might not always know what your local area code is. If you are on the edge of one area, the signal may flip back and forth to cell towers on either side of the line. For that reason, we always have to include an area code, even if we’re only calling next door.
In terms of locating a cellphone, it isn’t like locating a landline. A landline is a fixed, physical wire which never moves. For that reason, the phone on the end of it will always have the same number. It will also always be at the same location. Phone companies keep records of which number terminates at which address. In simple terms, this is the phone book. Even if you are not listed in the phone book, the phone company still knows where you are. This information is made available to law enforcement, so tracing a landline call is really quick and easy. Cellphones, though, aren’t so straightforward.
Imagine that you’re driving along the freeway doing a very legal 55mph. Someone (not you) is using a cellphone. This means the cellphone is also doing 55mph, and taking the call connection with it. Within a minute or two, you have driven past 3 cell towers, and the call has been transferred to each one seamlessly. No problem so far. But what if you’re being kidnapped, and in the trunk of the car? Dialling 911 is the best idea, but how will they know where you are? By the time they have your signal traced, you can be a mile up the road.
When 911 operators do need a location for a cellphone, they use mast triangulation. At any one time, your phone signal is bouncing off 3 network masts. Law enforcement software is able to establish a rough position based on the distance from each of the masts. This location is surprisingly accurate, and might be correct to within about 200 feet. It is also usually available to the dispatcher in a few seconds. But is that enough? Well, if you’re in the middle of a field, it probably is. Otherwise, it might not be quite so helpful.
An apartment block might be 10 storeys or more high. Triangulation will indicate that you’re in the building, but there’s no way of knowing which floor you might be on. Even in a residential street, 200 feet might include several separate buildings.
There is a higher level of accuracy available for cellphone locations. Unfortunately, these details are only available to the phone carrier. They do respond quickly to requests from law enforcement, but it still takes valuable time to make the request and receive the information. The more accurate location is achieved by “pinging” the cellphone. This is where a simple signal is sent to the phone, and the phone automatically responds to say where it is. Again, environment and terrain will have a big say in exactly how accurate this second tier location actually is.
It’s a good question. Those phones which can transmit a GPS location, do so automatically to the mast when a call is connected. The problem is that fewer than 70% of cellphones in use in the US are either able to do so, or that the carrier being used can’t utilize the information well enough. The FCC and the carriers are working towards a solution, but 100% coverage is a long way off.
In addition, not all counties have the ability to show the position on a map, and still rely on the caller to provide a location. This, as you can imagine, is less than ideal.
Yes it is. And when a free app can tell one person where another is, instantly and in real time, why is the 911 system so far behind in the technology it uses? One problem is that, despite the FCC being a federal – and therefore nationwide – body which regulates such things, it isn’t enough. States, and even counties, still have a lot of autonomy in deciding on the equipment they use. Rural areas simply can’t afford to be spending half a year’s budget on a single location system, for example. And so, they don’t.
The bottom line is that, until regulation both unifies the systems used, and compels counties to use them, not much will really change. If that means public money being invested from the federal government, then that’s what needs to happen.
Until then, if you do need to call 911 and you’re not at an address you know, there are still things you can do. Look for any markers or potential points of interest. Street names, stores, statues or other monuments will all help. Anything, basically, which might give the 911 dispatcher some help in identifying your position. More and more 911 call centers are able to receive texts. Learn how to use your phone to send your GPS location by text, and put it on your home screen. It might just save your life.