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Deep Intel on Nomadic E911 Service

Deep Intel on Nomadic E911 Service

E911 History Lesson

When I first started working, way back in the 80s, every person had a phone that went through a main phone system called a PBX. The PBX hung on the wall in the telephone room of the building where my office was located and the PBX had a large voicemail system attached to it and it was all tied to the Public Switched Telephone Network (PSTN) through land lines, in this case, PRI. Every outgoing phone call went through the PBX and out of the building on those PRIs. As a result, if a call was made to 911, the address of our building was the location of the caller.

By the early 90s, I started to use a cell phone at work but it was really only used when I was away from the office. And it was completely independent of our in-office PBX. Here we are in 2024, and boy have times changed. The much more fluid and flexible means of voice communication such as cell phones and VoIP (Voice over Internet Protocol) have complicated the ability to deliver accurate location identification when dialing 911. E911 location services are critical to effective emergency response as when you dial 911, the call is routed to the closest servicing PSAP (Public Safety Answering Point) to where you are calling from. Therefore, it is essential to find a way to assign locations to all calls, whether they made over analog, PRI or… VoIP.

So, let me introduce you to Nomadic E-911… which provides the ability to dynamically track the location of users as they move around a campus or to other physical locations to ensure their location is up to date in the event of an emergency and the need to call 911.

How E911 works

Calls to 911 are routed to a Public Safety Answering Point (PSAP). E911 identifies the location of the caller and routes the call to the appropriate local PSAP. It then provides the PSAP with location information (like 1010 Wayne Avenue, Silver Spring, MD 20910), enabling emergency responders to dispatch to the caller’s location. Standard E911 for VoIP is enabled by setting a physical address to show up when 911 is dialed. This location can be updated if your work location changes. If I were to move from our Silver Spring Data Center to our Rockville Data Center, I would change my E911 address to 1201 Seven Locks Road, Rockville, MD 20854. The key thing to note here is that the address associated with the number and provided to the PSAP is static and not necessarily a representation of live location information. In this case, first responders can get to the right address, but they don’t know exactly WHERE in the building I may be.

This is resolved with Nomadic E911 as the dispatchable location includes ALL of the caller’s current location information, the street address plus additional information such as suite, apartment, or similar information necessary to adequately identify the location of the calling party. Nomadic E911 uses PIDF-LO (Presence Information Data Format-Location Object) to embed location information in SIP headers using XML format. This format allows organizations to send a caller’s location information to the PSAP in IP-based 911 networks. Essentially, 911 calls can be routed according to the location of the Wi-Fi hotspot (or a network switch…. the hotspot/switch has the PIDF-LO information in its configuration), rather than a static address that may or may not represent the caller’s actual location. This capability makes Nomadic E911 the ideal solution for an enterprise where callers frequently move around multi-tenanted addresses, high rises, or large campuses.

What is Nomadic E911?

The rise in remote and hybrid working has prompted a rise in the use of non-fixed telephony, such as VoIP phones and UCaaS solutions such as Microsoft Teams. This presents a challenge when identifying the exact location of a caller making a 911 call. Nomadic E911 requires service providers to dynamically track the location of users, to ensure their location is up to date in the event of an emergency. As with fixed telephony, those that deliver non-fixed telephony need to provide dispatchable location information. This means that those that deliver non-fixed interconnected VoIP services, mobile text, and telecommunications relay services (TRS) need to strive to deliver automated dispatchable location where technically feasible. Now with Nomadic E911 non-fixed telephone service providers are required to provide a current dispatchable location. Again, this is achieved using PIDF-LO technology (Presence Information Data Format Location Object). Essentially, 911 calls can be routed according to the location of the Wi-Fi hotspot, rather than a static address that may or may not represent the caller’s actual location. This is known as Dynamic Location Routing (DLR)

These changes to regulations and in practice bring non-fixed telephony in line with fixed telephony, just like “back in the day”.


Tom Collins
Post by Tom Collins
March 7, 2024
Tom is the Director of Enterprise Sales & Marketing for Atlantech Online. He has over 20 years of professional experience in the Internet Service Provider industry and is known for translating technology into positive results for business. A native of Washington, DC, a graduate from University of Maryland (degrees in Government & Politics and Secondary Education), Tom is also a five-time Ironman finisher.