Next Generation 911

by Andrew Prokop | Arrow Systems Integration

We all have a fundamental understanding as to what happens when we pick up a telephone and dial 911. We expect that our call will be answered by an emergency response specialist close by and not by someone hundreds of miles away. However, have you ever thought about how that happens? Have you thought about all the different ways that that call might be made? Does the call go through the same set of steps when it’s made from that analog telephone in your house as it does when it’s placed from a cell phone? How is it different when the call is made from a business phone attached to your company’s PBX? What if that business phone is on a gateway halfway across the country? How does 911 work if you are in a hotel room and you make the call from a soft phone on your PC? What happens when a deaf person makes a 911 call from a TTY device? It’s getting complicated, isn’t it?

911 consists of a several functional areas. There is the telephone you are calling from. As I mentioned above, that phone can be any number of different devices connected to the telephone network in many different ways. Then there is the phone system that initially processes the call. That might be a PBX, a cell carrier, or the local phone provider for that landline in your house. Next comes the 911 network components. I am lumping together all the functionally that figures out where to send the call and what information should be associated with that call (e.g. street address, the floor number of a building, a pillar number within your workplace). That location information is Automatic Location Information (ALI). The entire “lump” of network components is referred to as the 911 Tandem. Lastly, there is the emergency response center. In 911 lingo we call that the Public Safety Answering Point (PSAP). When we hear a 911 call played back on CCN we are listening to a conversation that occurs at the PSAP.

Now, I could go into great deal about those functional areas and how a call actually flows through them, but for this blog all you really need to know is that when a 911 call is placed, the caller is connected to a PSAP responder (they do not like to be called operators) and the information about where the caller is calling from is displayed on the responder’s computer console.

This is all fine and dandy and for the most part it works. At least it works in the confines of a system that was designed decades ago and continues to use old and often obsolete equipment and concepts. For instance, the location information about the caller is limited to 240 characters. Additionally, that location information is often sent to the PSAP across antiquated analog CAMA trunks that use DTMF (telephone touch tones) to pulse the data in something akin to Morse code. Also, when a deaf person uses a TTY terminal to make a 911 call the data that he or she types is sent to the PSAP at 45 baud. Heck, I am a lousy typist and I bet that I can type faster than 45 baud.


All of this leads me to what I would really like to talk about – Next Generation 9-1-1 (NG9-1-1). NG9-1-1 recognizes the need to rethink how 911 calls are processed in terms of the technology and human experiences that are common today. By technology I am, of course, referring to SIP. After all, this is primarily a SIP blog. By human experience I am referring to the fact that the world has moved beyond basic telephones and TTY devices. These days we use our telephones for text as much as we do for voice (and if you are less than 20 years old, I would say more). We have also moved to where video applications are plentiful and easy to use. In terms of that TTY, wouldn’t it be a lot more efficient if the deaf caller could establish a video session with the emergency responder and use American Sign Language (ASL) instead of typing his or her emergency?

SIP is the ideal protocol for NG9-1-1 for a number of reasons. First, it is media agnostic. SIP can establish any kind of real time communications flow that you could possibly imagine. While voice, video, and text are the primary concerns of NG9-1-1, SIP is ready to support anything else that might be useful in the future. For example, what if you could use your smart phone to capture an injured person’s vital signs and send them to the emergency responder? Is that too farfetched to imagine? Not for me.

Second, SIP isn’t limited to 240 characters pulsed across an analog trunk after the 911 call has been answered. You can embed far more than 240 characters in a SIP message. Better yet, you can send links that can be used to access large blocks of information that may be of a dynamic nature. Picture this, you place an NG9-1-1 call and as part of the SIP message you pass a link that can be used to retrieve the real time video from a surveillance camera. Image how much better an emergency could be handled if the responder could see what was happening at that very moment.

I could write about NG9-1-1 for hours, but the point of this blog is to simply introduce you to the topic. I think this is all pretty exciting stuff, though, and plan on returning to this topic in the near future for deeper dives into specific functional areas. As always, stay tuned for more.

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