Who Moved My ALI?


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Since the NENA Additional Data Work was reinstated last July, the team has focused almost exclusively on what NG9-1-1 refers to as Additional Call Data.  This subject was tacked first, since most of the concepts already exist in the “legacy” Automatic Location Information (ALI) which is currently made available to 9-1-1 telecommunicators alongside each 9-1-1 call; this makes for a good “warm up” project. There are also a number of groups looking at the future of ALI from different angles:  from IETF/ECRIT looking to finalize the Additional Call Data format, to NENA volunteers working out how data will be mapped between legacy ALI and NG9-1-1 data structures.  Consequently, this is a critical time to give input into documents and standards affecting this area.

Through this process, we’ve heard from carriers, solutions providers, and those serving on the front-lines of public safety and 9-1-1 dispatch.  We’ve heard loud-and-clear that ALI, and the information it carries (such as Class of Service, or CoS), is critical to call handling and dispatch.  However, ALI, as we know it today, does not exist in NG9-1-1.  Panicked yet?  Let me explain … .

Where did ALI go?

While caller location is typically the first thing that comes to mind when considering ALI, there are several kinds of information that are carried by this data format.  The current categories of legacy ALI data, and where they appear within NG9-1-1 are outlined below:

“ALI-like” data is present and accounted for, although you’ll have to look a few places to find all of it.

How do I know I won’t lose information?

When first evaluating the proposed Additional Call Data specification our first question was not what new features will it enable, but whether the capabilities delivered minimally match ALI.  This was accomplished by mapping the existing ALI Subscriber, Service, and Carrier describing information to the proposed Additional Call Data specification.  We found the majority of the legacy data accounted for, and raised remaining gaps to the IETF’s ECRIT work group.

This research continues at an even deeper level.  Volunteers from Intrado are mapping all relevant ALI fields (not just those dedicated to Subscriber, Service, and Carrier information) to their equivalent NG9-1-1 data sources.  The outcome of this effort will ultimately be added to the NENA i3 Specification.

What if my PSAP is not NG9-1-1 ready?  Will ALI disappear?

No! NG9-1-1 provides for components called “Legacy Gateways” which bridge the differences in NG9-1-1 and “legacy” technologies.  The natural focus is on completing the 9-1-1 call itself, however these components are also tasked with converting ALI records into NG9-1-1 ready datasets (where a “legacy” telephony network touches a NG9-1-1 network) and NG9-1-1 data into ALI records (where a NG9-1-1 network delivers calls to a “legacy” PSAP).  It is this latter “Legacy PSAP Gateway” that will generate the resulting ALI records for PSAP’s which are reliant on ALI.  In time, the need for Legacy Gateways should pass, as all network components become NG9-1-1 capable.

Should we mourn the loss of ALI?

I don’t think so.  ALI has served us well, but ALI data structure was created long before mobile phones were placing 9-1-1 calls, and “calling” 9-1-1 via voice, video, and text through various computing devices was not even a twinkle in a Tandem-switches status lights.  Consequently, support for these forms of communications is less than ideal, or wholly unsupported.  For example, completing a VoIP call frequently involves a number of services providers (a network provider and a VoIP provider), where ALI can only describe the VoIP provider.  Another example is Class of Service, which attempts to communicate too much information via a small number of values.  See Kathy McMahon’s article in the March issue of APCO’s Public Safety Communications for further reading on CoS.

What happens going forward?

It is clear that NG9-1-1will greatly improve the type and quality of information available to support public safety in their mission.  To date, NG9-1-1 has been heralded for its promise to carry new forms of communication, increase collaboration across public safety agencies, and to possibly reduce network costs.  I think there are equally exciting capabilities enabled by driving additional data into the PSAP, from improved call description, through delivering extensive information about the caller (as provided by Smart911).

My counsel to “customers” of NG9-1-1 (telecommunicators, floor managers, and those supporting PSAP technology) is to list the problems you have been struggling with, and ask your technology partners to use the introduction of NG9-1-1 to help solve them.  Rather than mourn the passing of ALI, let’s rethink how you receive and interact with this data.  Opportunities to reinvent a service like 9-1-1 come but once a career!

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