by John A. Browne
The wireless revolution within the telecommunications industryis seriously
jeopardizing the telephone companies’ ability to provide locationinformation
as part of a 9-1-1 call. Wireline service is a fixed environment.With minor
exceptions (foreign exchange and off premise extensions),wireline calls
originate from a service address, so when a call is made to9-1-1, the service
address can accompany the call and display as locationinformation. Wireless
service, on the other hand, is a variable environment. There isno telephone
cord to tether the wireless communications device to a specificservice
location, therefore there is no means within the current 9-1-1architecture to
determine or provide location information in the event of a callto 9-1-1.
The architecture of the 9-1-1 system is starting to show its age.It’s based on
wireline technology and doesn’t provide the flexibility necessaryto support the
wireless environment. It’s time to design a new architecture thatwill
accommodate both the wireline and wireless environments. Isuggest a set of
“Strategic Imperatives” (musts) that integrateslatitude, longitude and altitude
(with degree of accuracy indicator), abbreviated as”Universal Address” and a
ten digit Calling Party Number (CPN) as basic elements of the9-1-1 network
fabric. The Universal Address needs to adhere to a singlestandard format
(GPS as an example). This will enable all interfacing systems tocorrectly
interpret and process the information in a uniform way. Thescience of
providing altitude with any degree of accuracy has not matured,but creating a
place holder for it in the “Universal Address” isimperative. Science will
catch up and the 9-1-1 infrastructure needs to be ready when itdoes.
It is imperative to 9-1-1 that the following is provided.
Wireless 9-1-1 Calls (calling devices and/or wireless endoffices):
* Ten digit CPN
* Universal Address
Calls made to 9-1-1 must include a ten digit CPN and theUniversal Address.
This information is needed to provide both call routing to theappropriate 9-1-1
agency and accurate location information. Little information issent forward
relegating the wireless 9-1-1 caller into a standard 9-1-1service situation, i.e.
no selective routing or display of definitive locationinformation at the
Voice Network (including end office):
* Ten digit CPN
* Universal Address
Wireline originated calls made on the voice network must becapable of
forwarding a ten digit CPN. The geographical boundariesassociated with
today’s number assignment rules don’t mean much any more with NPA
overlays, deregulation of the local subscriber loop and telephonenumber
portability (you own the number, you move and the number moveswith you).
A ten digit CPN will provide us the means of keeping everythingsorted out.
For wireless calls, the network must be able to forward theUniversal Address
and ten digit CPN. The only way location information can bederived from a
wireless is through the interpretation of the Universal Address.
Today’s network is only capable of supporting a seven digit CPN.Not very
helpful when you consider the roaming capability currently in usein the
cellular and soon in the PCS environments compounded byderegulation and
phenomenal telephone number growth.
9-1-1 Call Routers (Tandems):
* Ten digit CPN
* Universal Address
* Forwarding of the Universal Address and 10 digit CPN to theservice 9-1-1
* Upgraded CPN architecture
The 9-1-1 Call Routers must be able to route calls utilizing theUniversal
Address when processing wireless calls to 9-1-1. Overlappingpolitical sub-
division boundaries and jurisdictions (Highway Patrol, Sheriffand Police)
require greater precision in call routing, i.e. being able todistinguish between
a freeway overpass (Highway Patrol jurisdiction) and the citystreet below
(Police jurisdiction) will help to save lives. Routing calls byUniversal
Address will enhance the opportunity to correctly route wirelesscalls the first
time. Likewise, wireline calls to 9-1-1 need to be routed to theappropriate 9-
1-1 agency based on Universal Address. The Call Router shouldstore as part
of the wireline telephone number record the applicable UniversalAddress
associated with the location of that telephone number. Telephonenumber
updates containing ESN and Universal Address would be provided ina similar
fashion that telephone number/ESN updates are provided today.
The Call Routers must be able to not only forward the ten digitCPN, but also
the Universal Address to the 9-1-1 agency. The Universal Addresswill
provide location coordinates for the graphical map display at theagency, while
the ten digit CPN will display at the agency and provide theappropriate
address information via the 9-1-1 ALI retrieval data base and theappropriate
call back number.
The ANI trunks or basic network architecture must be upgraded tofit today’s
technology. As SS7 and ISDN continue to mature, they offerpromise of an
early solution for the E9-1-1 application. Call setup time,delivery of larger
data packets and self healing are all issues that need to beaddressed and
9-1-1 Call Taking Agency:
* Intelligent workstations
As I heard said in Nashville at the 1995 NENA Telco/VendorConference,
“bubba don’t do lat long” really sums it up. 9-1-1agencies’ call taking
equipment must be upgraded to accommodate dynamic display ofgraphic
location, in the form of a map, CPN and location address. Thiswill require
new terminal equipment, an intelligent workstation. Thisworkstation will
provide the 9-1-1 call taker the interface necessary toeffectively utilize the
information made available. It will store graphic maps anddisplay graphic
location information based on the Universal Address, display theCPN and
address. The display maps would be stored locally in an effort tospeed the
display of information. Master maps would be stored at a centraldepository
and as maps are updated, through MSAG maintenance, localrefreshes would
be down loaded as appropriate.
ALI Data Network:
* Wider band width
* Ubiquitous self healing
The ALI data network must have a wider band width. Graphic ALIdisplays
utilizing graphic location data protocol at the 9-1-1 agency willcreate an
additional strain on the “ALI Data Network.” Not onlywill the network
provide location address information, but it also will be thevehicle to keep the
graphic ALI maps at the 9-1-1 agencies updated. In order to keepfrom
‘clogging’ the network, greater data transfer rates are required.A ubiquitous,
self healing network is a must. Greater reliability and diversityis required to
provide the service and performance levels essential to 9-1-1.
9-1-1 Data Center (9-1-1 Management System)
* Graphical Master Street Address Guide (MSAG)
* Graphical interface for administration of MSAG
* Communication link with 9-1-1 agency for map refreshes
The 9-1-1 Data Center must convert the current tabular data baseand Master
Street Address Guide (MSAG) to graphical. Latitude, longitude andaltitude
coordinates must be associated with all known address ranges. Thetelephone
number data base must be able to support ESN, location andUniversal
Address information for all working wireline numbers. Thisrepresents a
major change in the design of the Management System. Today, in atabular
fashion, working wireline telephone numbers along with associatedlocation
information and ESN are stored in the data base. This method isbecoming
more and more ineffective as we get deeper into the wireless andthe new
deregulated multi-dialtone provider environment.
The interfaces between the E9-1-1 Management System and the MSAG
maintenance must be converted to a graphical interface. This willrequire a
technological upgrade to end-users equipment and has a dependencyon
method, style of the change and update techniques adopted.
Based on current thinking, the Management System will performarchive and
updating facilities for the graphical location maps utilized atthe PSAPs. This
will require more bandwidth on the network connections betweenthe PSAPs
and the 9-1-1 Data Centers. Although the graphical images are notmassive,
speed of refresh is a significant consideration. (Everyone willhave their own
thoughts on this subject, but remember in this instance more isbetter.)
9-1-1 Data Center (ALI Retrieval):
* ALI retrieval by ten digit telephone number (wireline)
* ALI retrieval (proximity location) by Universal Address
The ALI retrieval system must be able to provide locationinformation based
on ten digit telephone number input from wireline calls. Theoutput would be
the service location of the wireline call displayed at the PSAP.For wireless
calls, the ALI retrieval system must be able to provide proximitylocation
information (corner of 7th and Olive) based on Universal Address.Display of
this location information at the PSAP would be in addition to thegraphical
location display resulting from the processing of the UniversalAddress
forwarded from the 9-1-1 Call Router by the intelligentworkstation.
The time for change is now, before we are completely overtaken bythe
revolution. The thread that ties the 9-1-1 call to the servingagency is a ten
digit CPN and the Universal Address. The introduction of thesekey
components to the 9-1-1 network, 9-1-1 Call Routers, ALIretrieval systems
and Service Agencies will provide the means necessary to provideaccurate call
routing and location information for all calls made to 9-1-1.
The only way these changes will take place is if we all getinvolved and speak
as a unified voice. Let’s get involved and make this happen now.Tomorrow
is too late.
John Browne is Director of Technology, 9-1-1 & EmergencyServices, of
Pacific Bell, headquartered in Concord California. He has beenwith Pacific
Bell for twenty-nine years and has spent the past five yearsworking in 9-1-1.
Over the span of his career, he has developed a wide array ofexperience in
areas such as PBX installation/maintenance, electronic switchingand software