Planning for and deploying emergency services within Skype4B/Lync is in my top-three items that customers simply fail to understand both from a technical level and from a policy level.  Some people don’t get the technology requirements.  Some people don’t get the regulatory requirements.  Some people insist they won’t spend money for a “required solution”, or in other terms, something they don’t think they need.  In my opinion, we focus far too much on the technology solutions and forget the most important element of the discussion:  human beings.  Co-workers.  Managers.  Executives.  Friends.  The decision and design of emergency services within any communications platform is not simply a technology decision but a combination of policy requirements, regulatory requirements and technology solutions.  In the United States, there are strict regulatory requirements in many states that force businesses to properly provide for E9-1-1 services not because the government wants to purposefully force additional dollars spent by businesses, but because government recognizes that the safety of its citizens is important.  You can argue all you want about “increasing red tape” and “too much government oversight” but if we all take a step back and be honest with ourselves, I believe that we’ll all arrive at the same conclusion:  protecting human life, to the best of our abilities, is worth the time and money.

In the aim of protecting human life, this multi-part series will examine the core principals of 911, enhanced 911 and the integration with Skype4B/Lync so that administrators and architects can begin to incorporate the knowledge into their own environments.  If you are a seasoned veteran, then maybe this will be a refresher course on a topic that often doesn’t get the attention it should.  If you are a newcomer, then hopefully you learn something new.  If you are somewhere in between…welcome to the club.  😉

The Alphabet Soup of Emergency Services

Quite frankly, the list of terms involved in 9-1-1 is overwhelming and often times very confusing.  Simply looking at the list is enough for a person to have their eyes gloss over, shrug their shoulders and move on.  What you see below is my attempt to “humanize” the terms you need to know:

NENA – National Emergency Number Association This is a professional policy organization that helps develop policies, technology and education in relation to emergency communications.

Bottom line:  This is essentially the brain trust of 9-1-1.

E9-1-1 – Enhanced 9-1-1 A system, which includes network switching, database and PSAP elements capable of providing location identification data, selective routing, and a call back number. E9-1-1 relies on coordination between business and telco providers to ensure the system truly works.
NG9-1-1 – Next Generation 9-1-1 An enhancement of existing 9-1-1 and E9-1-1 systems with a long-term goal of replacing them.  NG9-1-1 is an Internet Protocol (IP)-based system that allows digital information (e.g., voice, photos, videos, text messages) to flow seamlessly from the public, through the 9-1-1 network, and on to emergency responders.
Selective Router A device utilized by telcos that provides automatic switching and routing of 9-1-1 calls and delivers calls to the PSAP.  Selective Routers use Selective Routing to properly route 9-1-1 calls.
Selective Routing The process by which 9-1-1 calls/messages are routed to the appropriate PSAP or other designated destination.  Location may be provided in the form of an MSAG-valid civic address or in the form of geo coordinates (longitude and latitude). Location may be conveyed to the system that performs the selective routing function in the form of ANI or pseudo-ANI associated with a pre-loaded ALI database record (in Legacy 9-1-1 systems), or in real time in the form of a Presence Information Data Format – Location Object (PIDF-LO) (in NG9-1-1 systems).
PSAP – Public Safety Answering Point This is a facility, within your locale, where a 9-1-1 call is ultimately delivered so that an operator can answer your call.  Sometimes there is a single PSAP in your town and other times there are multiple.  You don’t control which PSAP you use when you call 9-1-1.

Bottom line:  this is where your 9-1-1 calls go to.

ANI – Automatic Number Identification This is the DID transmitted when you make a normal outbound telephone call.

Bottom line:  this is the number associated with your caller-ID

ALI – Automatic Location Identification This is the general information the PSAP operator sees on their computer screen when they answer your 9-1-1 call.  The information is based off the location information associated with the ANI of the call.  In most cases the civic address information is the billing address or service address of the circuit and does not contain specific location information such as a floor, wing, or office.
Civic Address This is a city-style address that includes a house number and a street name.  Civic addresses may not exactly match MSAG addresses, due to formatting differences. Ideally your civic address formatting should match the MSAG address formatting.  Example:

333 Commerce Street

Nashville, Tennesse 37021

United States

CAMA – Centralized Automated Message Accounting This is an analog transmission protocol that transmits telephone number information.  This is a legacy protocol but still used within some PSAPs.
DID – Direct Inward Dialing This is a telephone number that allows a caller to reach someone on another telephone system.  The “direct inward” implies that dialing the DID will allow reaching the callee directly, bypassing an operator or auto-attendant, but that is not always true in practice.
ISDN PRI – Integrated Services Digital Network Primary Rate Interface This is a type of digital phone circuit and is the international standard for public communications networks.  This is the most common phone circuit provided to businesses today.
MSAG – Master Street Address Guide This is a database of street names and house number ranges that provide authoritative civic address data for 9-1-1.  It ensures that every house number and street name is absolute and unique to guarantee 9-1-1 routing to the right PSAP.  Example:

333 Commerce St

Nashville, TN 37021


PS-ANI – Pseudo Automatic Number Identification This is identical to ANI, with one critical exception:  the DID used is dedicated for 9-1-1 calls only.  No other outbound calls can use the ANI associated with PS-ANI.
PS-ALI – Pseudo Automatic Location Identification This is identical to ALI, with one critical exception:  the information the PSAP operator sees on their computer screen references specific information that is tied to the PS-ANI.  Thus, the PS-ANI contains civic address information and other location information, such as a floor, wing or office number.  PS-ANI and PS-ALI are the two telco technologies that make E9-1-1 possible with ISDN-based systems today.
PIDF-LO – Presence Information Data Format Location Object This is XML formatted information, contained within SIP messaging, that represents location information.  Each of the LIS fields in Skype4B map to one of the PIDF-LO fields:

LIS Field PIDF-LO Field
Location LOC
CompanyName NAM
HouseNumber HNO
HouseNumberSuffix HNS
PreDirectional PRD
StreetName RD
StreetSuffix STS
PostDirectional POD
City A3
State A1
PostalCode PC
Country Country
ERL – Emergency Response Location A location to which an emergency response team may be dispatched.  The location should be specific enough to provide a reasonable opportunity for the emergency response team to quickly locate a caller anywhere within it.  The specificity of ERL requirements is typically dictated by E9-1-1 legislation and internal requirements.  In general it includes civic address information plus specific location data, such as a floor, wing, office number, or other identifying information.

Examples of Location Data:

Floor 5

Floor 5-SW Wing

Floor 5-Room 210

ELIN – Emergency Location Identification Number A valid telephone number, tied to PS-ANI and PS-ALI configuration, that is assigned to an ERL for the purposes of 9-1-1 calling.  A call from an ERL will specify the ELIN as the caller-ID for 9-1-1 calls, allowing PSAP operators to see specific information about the caller’s location based on the database information available for the caller-ID on the call.

Does your head hurt yet?  Uh huh, I thought so.  It seems like a complete jumble of words and concepts, but let me pose a scenario that might help to explain why it’s all needed…

The Scenario

Assume for a moment that I work here:


333 Commerce St, Nashville, TN 37021, United States

There are 33 floors in the building and my employer leases floors 10-20.  Each floor has approximately 20,000 sq. ft.  I am working late one day on floor 19 and have a medical emergency, such as a seizure or heart attack or anaphylaxis, and dial 9-1-1.  The PSAP operator answers, can hear me gasping for air but I am unable to tell them where I am…and then I go unconscious.  If E9-1-1 hasn’t been properly set up within my company’s phone system (and with the telco), there is almost a virtual certainty that I would die.  “Surely not!”, you say, but without E9-1-1 there are multiple avenues of failure:

Question 1 – What ANI does my phone system send to the telco and what address is configured for that ANI?

  • Maybe the company sends the main office number (6155551000) but the address information within the telco’s database corresponds with Floor 10 of the building.  I’m physically calling from Floor 19, so emergency responders will go to the wrong place.  OR…

Question 2 – What ANI does the PSAP operator receive and what address is configured for that ANI?

  • Maybe the company sends a number that the telco doesn’t recognize (6155551000) and the telco passes on the billing number to the PSAP (6155552000) instead.  The billing number information within the telco’s database corresponds with the building only – no floor information – which may result in complete confusion when emergency crews arrive to the building and don’t know which floor to search.  OR…

Question 3 – If the PSAP operator sees location info, is it specific enough?

  • Maybe the company sends a specific number (6155551000) and the PSAP operator sees the location as specific to floor 19.  Given that there is 20,000 sq ft of office space per floor, how long will it take the emergency responders to find me?  Would I still be alive if they did?

For nearly all current ISDN-connected multi-line phone systems, the only real information you can send for a 9-1-1 call is the proper caller-ID (ANI or PS-ANI), so these questions are critical because they ultimately tell us where emergency services will be sent to based off the location information within the telco database for the ANI/PS-ANI provided on the call.  For nearly all current SIP trunk connected multi-line phone systems, unless both your phone system and the SIP trunk from your telco supports PIDF-LO then the information you can send for 9-1-1 calls is no different than legacy ISDN-based scenarios.

To put it bluntly, sending the right ANI/PS-ANI can be a life or death situation.

The Concern

I can already hear the rebuttals coming…

  • A receptionist would be there to guide them!
  • An alarm on the phones would show the extension making the call!
  • Another person would be around to assist and communicate with the PSAP!
  • Building security would be alerted in the event of a call!
  • A person could use their cellphone and their location would be provided automatically!

If the call was during business hours, a receptionist or another person could meet the emergency responders and guide them to me.

If alarms on phones could alert others in the event of a call, another person is more likely to see it and potentially be able to assist.

If the call was during business hours, there may be someone next to me who could communicate with the PSAP operator.

If the building security had integration with your phone system, they could see the alert and potentially be able to assist.

If a cell phone was available and had signal, the call may complete and may provide additional location data.


What happens when someone works late one night and then no one is around?

What happens when two separate emergencies occur on opposite sides of floor but the second emergency goes unnoticed due to the activity from the first?

What happens when building security has no additional information and must frantically search floor-by-floor to determine if there is an emergency?

What happens when GPS and/or cell-tower coverage is weak or the location information data is incorrect or too large to be effective?

What happens if an employee (or even a company guest) loses their life, on your property, and it becomes discovered that it could have been avoided?

Wrapping Up

Unfortunately not everyone can be saved – an unfortunate fact I learned as an Aquatics Manager at a waterpark in my earlier years – but the technologies and processes are available to make loss of life as small as possible.  Even if all the technology and policies in place, there are limitations that impact the overall solution.  The biggest limitation for any emergency is that emergency responders must physically travel to your location and the time of that travel is something that companies cannot control.  Even so, minutes are precious.  After 3 minutes of oxygen loss, the brain begins to become hypoxic and parts of the brain begin to die.  Beyond 5 minutes of oxygen loss, you risk coma, stroke,and ultimately death.  E9-1-1 and all the technology ‘mubo-jumbo’ in the table at the beginning of this post exists to help responders get to your exact location faster and save lives, if at all possible.  It is up to architects, administrators, policy makers, and telcos to craft solutions to make E9-1-1 work and provide the life safety we all expect.

Stay tuned – in the next part of the series we’ll look at researching your E9-1-1 requirements and how that plays in to Skype4B!

2 thoughts on “Enhanced 911 in Skype4B Server and Lync Server – Part 1

    1. Glad you have found it useful and are looking forward to the next post. As I said before, this is a multi post series, and in truth it will actually span more than just two posts. There is information on implementation forthcoming but that level of detail comes in Part 3, not Part 2. My new posts almost always release at 08:00 AM CST on Mondays so you should be able to do the math and plan out on when the information you seek will be available 😉

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