PSAP Operations Guide
for Wireless 9-1-1
July 2005
Notice
© 2005 Intrado Inc., Longmont, Colorado, USA - All rights reserved. Intrado, triangle beacon design,
Informed Response, and the logo forms of the foregoing, are trademarks and/or service marks of Intrado
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Trademark Information
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software, hardware, and firmware become available.
Intrado, therefore, reserves the right to change specifications without prior notice.
PSAP Operations Guide for Wireless 9-1-1
ii
Table of Contents
INTRODUCTION............................................................................................................. 1
A BRIEF HISTORY OF WIRELESS E9-1-1 ................................................................ 2
GETTING READY FOR PHASE I.......................................................................................... 5
GETTING READY FOR PHASE II ........................................................................................ 7
PHASE I OVERVIEW ..................................................................................................... 8
PHASE I TECHNOLOGY OVERVIEW ................................................................................... 9
PHASE I—WHAT THE DISPATCHER SEES ....................................................................... 13
PHASE II TECHNOLOGY OVERVIEW ................................................................... 15
GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS ........................................................ 16
OTHER SOLUTIONS ........................................................................................................ 17
ACCURACY TESTING AND VERIFICATION....................................................................... 17
PHASE II—WHAT THE DISPATCHER SEES ...................................................................... 18
LOCATION RE-QUERIES AND MID-CALL UPDATES......................................................... 19
FREQUENTLY ASKED QUESTIONS........................................................................ 20
GLOSSARY..................................................................................................................... 22
PSAP Operations Guide for Wireless 9-1-1
iii
INTRODUCTION
Authorities involved in 9-1-1 find themselves facing ever changing and new technologies
giving people the ability to access emergency services by multiple means. This
document provides information about wireless Enhanced 9-1-1 (E9-1-1) history,
technology, mandates, and implementation activities. Intrado Inc. has been involved in
developing processes, identifying technical methodologies, and deploying wireless E9-11 since 1996. This document represents the collective knowledge of individuals who
have faced similar challenges. Intrado provides this information to help you deploy, train,
and understand wireless E9-1-1.
PSAP Operations Guide for Wireless 9-1-1
1
A BRIEF HISTORY OF WIRELESS E9-1-1
Earlier solutions for wireless E9-1-1 implementation were developed based on the call
flow model that E9-1-1 systems have been operating under since the 1970s. Alternative
solutions have been developed that minimize the economic impact of adding wireless to
the existing E9-1-1 infrastructure. There are a few core methods used by Intrado and
others for connecting wireless calls through the Mobile Switching Center (MSC) to the
Public Safety Answering Point (PSAP) and moving the call-back number and cell site
information either directly to the PSAP or to the Automatic Location Identification (ALI)
database for subsequent display at the PSAP. Those methods are discussed later in this
document.
Wireline E9-1-1 infrastructure has been implemented in the United States since the
1970s, using primarily analog technology. The wireline version of E9-1-1 uses a single
telephone number—Automatic Number Identification (ANI)—to route the call and retrieve
the data that provides PSAPs with information about who is calling and where the caller
is located. With the advent of wireless telecommunications—and its inherent mobility—
the "who" and "where" were no longer associated with the caller’s telephone number.
The challenge in integrating wireless and wireline technologies is to provide the PSAPs
with essentially the same information to which they are accustomed to receiving from the
wireline system.
After several years of handling wireless 9-1-1 calls without any associated data, the
public safety community—embodied by several national professional organizations
(NENA, APCO, and NASNA1)—joined together in 1994 to officially lobby the Federal
Communications Commission (FCC) for service parity between existing wireline E9-1-1
systems and wireless services. The Commission requested that wireless subscribers be
provided the same level of service available to wireline subscribers. The result of the
Commission’s efforts was the opening of a Notice of Proposed Rule Making (NPRM) in
FCC Docket # 94-102.
The magnitude of the technical challenge became evident to the communications
industry and 9-1-1 professionals as soon as the NPRM was released for comment. The
result of these comments led the FCC to release a Report and Order (R&O) that
identified two phases of implementation, occurring over a specified time period, to allow
for appropriate technological adjustments to bring wireless service up to par with wireline
service.
Phase I requires that the calling party’s mobile telephone number and location of
the cell site and sector from which the 9-1-1 call originated be delivered to the
PSAP. The logic was that the caller’s number would be used to call back in the
event the connection was lost; and the location of the originating cell site and
sector would provide a level of location information that would allow delivery of
the 9-1-1 call to the appropriate PSAP.
1
NENA: National Emergency Number Association; APCO: Associated Public Safety
Communications Officers; and NASNA: National Association of State Nine-One-One
Administrators.
PSAP Operations Guide for Wireless 9-1-1
2
Phase II requires that the mobile telephone number and location of the caller,
within a specified accuracy margin, be delivered to the call taker in the form of
earth coordinates (latitude and longitude). This phase requires the incorporation
of new components into the wireless infrastructure to determine and provide the
specific location information.
When the FCC’s R&O was released, there were a limited number of location
technologies being used and tested in connection with the Department of Defense and
other research activities. Since that time, wireless use across the country has exploded.
In some markets, customers have actually chosen to discard their wired telephone
service in exchange for the much more portable and sometimes more cost-effective
wireless service. The growth can be seen in these numbers:
Year
Number of
Subscribers
1988
2 million
1993
16 million
1999
70 million
2002
134 million
2003
155 million
The first proposed wireless 9-1-1 solution used Call-path Associated Signaling (CAS).
CAS allowed for the caller’s wireless telephone number to be routed along with the voice
call to the PSAP. Both the Telecommunications Industry Association (TIA) and NENA
supported this solution. This method followed the existing wireline model: the caller’s
number (ANI) would arrive with the voice and be displayed for the call taker. In a wireline
E9-1-1 system, the ANI not only identifies the caller’s telephone number but is used to
retrieve the ALI from the 9-1-1 database. Given that wireless callers are often on the
move and there is no static relationship between their location and their callback
number, a modification was needed to route the call within the existing wireline
infrastructure. The response to this need in a CAS solution was the creation of a
pseudo-ANI (pANI) for each sector of each Phase I cell site. The pANI, like a telephone
number (ANI), is a ten-digit number that cannot be assigned to a wireless subscriber’s
telephone and is only used to provide routing and location information to the wireless
E9-1-1 system. Because the cell site, unlike the wireless telephone, is at a fixed location,
the pANI assigned to a sector of a cell site can be used to route the call to the correct
PSAP and retrieve the ALI from the 9-1-1 database.
A second issue related to ANI delivery was that some wireline systems used a type of
shorthand—or numbering plan digit (NPD)—for identifying the area code of the calling
party. The trunk group delivering each ANI to the selective router represented a specific
area code, or numbering plan area (NPA). In addition, there was a limitation of four
NPAs that any specific selective router could manage. In the wireless environment, a cell
PSAP Operations Guide for Wireless 9-1-1
3
phone user whose telephone has a New York area code can make a wireless call in
California as easily as local users who may need to make 9-1-1 calls. This means that
any number of NPAs had to be supported by a selective router. In order for the CAS
solution to work, network-signaling capabilities had to be enhanced to allow both the
caller’s callback number and a pANI in the delivery of a wireless 9-1-1 call to a PSAP. In
effect, the proposed solution more than doubled the number of digits—from eight to
twenty—that would be forwarded to the PSAP. This change created other issues within
the existing 9-1-1 systems, such as network capabilities, call set-up time, and limitations
of PSAP customer premise equipment (CPE). As a result, additional solutions emerged
for deployment of Wireless E9-1-1, including Non-Call-path Associated Signaling
(NCAS), Hybrid CAS, and NCAS with WID solutions.
PSAP Operations Guide for Wireless 9-1-1
4
GETTING READY FOR WIRELESS
This section highlights the steps necessary to become ready at the PSAP level to accept
wireless enhanced 9-1-1 calls and to have all the necessary data elements available to
the public safety professionals who are responsible for answering the caller’s request for
service.
GETTING READY FOR PHASE I
The PSAP must address administrative, operational, and technical considerations to
prepare for wireless E9-1-1.
For public safety related to Phase I, the FCC requires that the PSAP:
Is capable of receiving and using Phase I data
Has a mechanism in place to pay their costs associated with the service
Requests the service in writing from the wireless carrier.
When all of these requirements are met, the wireless carrier has six months—or 180
days—to either provide the service or have the consensus of the 9-1-1 authority for a
later deadline.
Deployment of Phase I service also requires that the PSAP coordinate with the Local
Exchange Carrier (LEC) and/or 9-1-1 service provider to do the following:
Assure and/or modify the ALI format to allow the wireless caller’s information to
be displayed correctly on the PSAP’s ALI screen
Request an Emergency Services Number (ESN) for wireless E9-1-1 calls
Request (from ALI provider) that appropriate MSAGs be built for wireless records
Determine the PSAP’s SR to PSAP trunking configuration for wireless calls.
Some considerations for this decision are as follows:
- Does the PSAP want both wireless and wireline calls to be transported
across the same trunks?
If the answer is yes, are there currently enough trunks?
OR
-
Does the PSAP want dedicated wireline and wireless trunks?
If the answer is yes, does the PSAP’s CPE need to be upgraded to
accommodate this configuration?
The following table shows the deployment process and roles and responsibilities during
the Phase I deployment process.
PSAP Operations Guide for Wireless 9-1-1
5
Item
PSAP
Send request for wireless E9-1-1 service (RFS) to
the wireless service provider (WSP).
LEC
Verify PSAP boundary.
3rd
Party
X
Notify Intrado (3rd-party provider) to proceed with
deployment.
Gather specific PSAP information.
WSP
X
X
X
X
X
rd
Provide MSC and cell site data to 3 -party vendor.
X
Plot wireless carrier cell sites on the verified PSAP
boundary map.
X
Perform network analysis/recommend an
appropriate number of MSC to SR trunks.
X
Order and install required MSC to SR trunks.
X
Connect MSC to MPC/GMLC (initial market
deployment)
Request/provide routing numbers.
X
Discuss PSAP ALI screen display format.
X
Determine default and alternate routing
requirements at the MSC.
X
Determine sector routing and PSAP cell sector
location description.
X
Determine whether new ESNs will be used for
wireless calls.
X
X
Ensure MSAGs are built to support wireless
deployment.
X
X
X
X
X
X
X
X
X
X
X
Provision ALI database records.
X
Provision E9-1-1 selective router.
X
X
Configure and provision MPC/GMLC.
X
Incorporate E9-1-1 translations into wireless
carrier’s MSC.
X
Verify network, selective router, ALI database and
MPC/GMLC readiness.
Determine testing schedule.
X
X
X
Provide all routing and test documentation.
X
X
Conduct pre-deployment testing of all network
components.
Conduct pre-production and 9-1-1 live call testing
at all cell sectors.
X
Declare 9-1-1 cutover a success!
X
PSAP Operations Guide for Wireless 9-1-1
X
X
X
X
X
X
X
X
6
GETTING READY FOR PHASE II
The considerations that have to be made for Phase II wireless E9-1-1 service are similar
to the considerations for Phase I.
For public safety related to Phase II, the FCC requires the following from the PSAP:
Is capable of receiving, displaying, and using the horizontal latitude/longitude
coordinates
Has a mechanism in place to pay their costs associated with the service
Requests the service in writing from the wireless carrier
When all of these requirements are met, the wireless carrier has six months—or 180
days—to either provide the service or have the consensus of the 9-1-1 authority for a
later deadline.
Note:
Many of the carriers have been granted waivers in reference to the six-month
deadline. Please check the FCC website at www.fcc.gov/911 to verify the new
date requirements.
As in Phase II, the PSAP must coordinate with the LEC and/or 9-1-1 service providers to
ensure the following:
The LEC and/or database provider has the proper interface in place to the
9-1-1 database. The current interfaces are E2, E2 Plus, or enhanced PAM.
The ALI format is modified to allow the display of the latitude/longitude
coordinates.
The 9-1-1 CPE can manually re-query the ALI database to request updates for
the location of the Phase II caller.
If the PSAP has chosen to interface with a mapping system and/or computer-aided
dispatch (CAD) system, the PSAP must make sure the interface and data format from
the 9-1-1 CPE to these systems meets all of the requirements to display and use the
Phase II data properly.
If Intrado has not verified your PSAP boundaries within the previous six months, Intrado
will contact you to verify the wireless jurisdictional boundary.
PSAP Operations Guide for Wireless 9-1-1
7
PHASE I OVERVIEW
This section starts with a high-level understanding of wireless Phase 0 and provides a
discussion of the technical solutions employed in wireless E9-1-1. A number of Phase 1
and Phase 2 solutions are discussed and illustrated with appropriate diagrams to provide
you with an overview of wireless 9-1-1. To develop an understanding of wireless 9-1-1, it
is extremely helpful to understand the wireline environment from which it evolved.
The Wireline E9-1-1 Call Environment
E9-1-1 networks components operate together in order to deliver a 9-1-1 call—including
caller data—to a PSAP. In the wireline E9-1-1 environment, a 9-1-1 call is placed from a
wireline telephone and sent to the local central office that serves that specific telephone.
The central office recognizes the call as 9-1-1 and forwards the call to a specialized
switch, referred to as a selective router. The selective router routes both the voice and
the caller’s telephone number (ANI) to the appropriate PSAP. The PSAP’s Customer
Premise Equipment (CPE) uses the ANI to retrieve the caller’s Automatic Location
Information (ALI) by querying the ALI database.
Landline Phone
911
Selective Router
Central Office
PSAP
ANI Controller
ANI (TN)
ANI (TN)
Workstation
ALI Controller
Location
Information
ANI (TN)
Telephone
= Voice Path
= Data Path
PSAP's
PSAP'sALI
ALI
What is Phase 0?
Wireless Phase 0 is the delivery of the wireless 9-1-1 call to a PSAP without the display
of any caller information. In most cases, Phase 0 calls are delivered through the public
telephone switch network to the PSAP. However, in some limited situations, Phase 0
calls may be delivered through the 9-1-1 trunks to the PSAP. If the call is delivered on
an administrative line and the PSAP subscribes to caller ID services through its LEC, the
telephone number of the wireless device may be delivered to the 9-1-1 call taker.
PSAP Operations Guide for Wireless 9-1-1
8
PHASE I TECHNOLOGY OVERVIEW
This section discusses the wireline and wireless E9-1-1 network configurations and
common Phase 1 solutions.
The Wireless E9-1-1 Call Environment
There are several Wireless E9-1-1 solutions currently deployed that provide the required
voice and data to a PSAP from the WSP’s network. These solutions can be grouped into
three basic categories: Call-path Associated Signaling (CAS), which uses an expanded
call signaling path through the E9-1-1 network; Non-Call-path Associated Signaling
(NCAS), which uses digital out-of-band signaling over a separate data path; and HybridCAS (HCAS), which uses an expanded call signaling path to the Selective Router and
out of band signaling from Selective Router to ALI to deliver the unique call data. In all
of these solutions the WSP must connect a voice and signaling path from its MSC to the
E9-1-1 selective router. This transports the caller’s voice to the PSAP. The MSC is a
switch that serves as the entry point for wireless calls received by multiple cell site
sectors into the public switched telephone network (PSTN) and performs a role that is
parallel to that of the end office in the wireline environment.
Non Call-Path Associated Signaling (NCAS) Solution
The NCAS solution uses a Mobile Positioning Center (MPC) or Gateway Mobile Location
Center (GMLC) that provides routing of all necessary data to both the MSC and the ALI
database. The call is routed by two (2) separate paths to the PSAP. Voice over the voice
path and ALI information over the data links are already in place. The voice call and
routing number—called an Emergency Service Routing Key (ESRK)—are delivered to
the PSAP through the serving 9-1-1 selective router. The MPC/GMLC dynamically
populates the callback number and cell sector location information data for this call into
the ALI database record indexed by the ESRK (aka pANI) assigned to the call. When the
PSAP receives the voice call, the ESRK retrieves a record containing the call-back
number and the cell site location data from the ALI database.
Cell Site
911
Selective Router
MSC
PSAP
ANI Controller
Telephone
ESRK
ORREQ/IAM in Message
ALI Controller
ALI Push
(ESRK, Loc Info, Callback #)
= Voice Path
= Data Path
Workstation
ESRK
Location Info
Callback #
(ESRK)
ORREQ Response/
IAM Out
911
(Send)
(MSC, Cell Site and Sector IDs,
Callback #)
ESRK
Acknowledgment
MPC
PSAP's
PSAP's ALI
ALI
NCAS Network Configuration
PSAP Operations Guide for Wireless 9-1-1
9
Call-Path Associated Signaling (CAS) Solution
The CAS solution delivers the caller’s voice and call-back number to the PSAP through
the voice portion of the network. The MSC forwards the call-back number along with the
voice using a routing number called an Emergency Services Routing Digit (ESRD) that
mimics the ANI for the purposes of 9-1-1 call routing. To accommodate the transmission
of both the ESRD and callback number, CAS requires that 20 digits of data be
transmitted to the PSAP along with the voice. The ESRD is pre-provisioned in the 9-1-1
selective router and ALI database, similarly to a wireline telephone record, to
appropriately route the call based on the cell sector that received it. When the call is
received at the PSAP, the ESRD serves as a lookup key into the database to retrieve
static cell sector location information.
While the use of the CAS solution is a viable solution for Phase I, this solution does not
have a migration path from Phase I to Phase II. CAS does not accommodate the
additional data—latitude and longitude—required to identify actual caller location (nor
will it in the foreseeable future). With a CAS solution, the SR, SR to PSAP trunks, and
PSAP CPE must be capable of receiving 20 digits (accommodating call-back number
and the routing number) through the voice call path. Often, the implementation of CAS
requires upgrades to selective routers, trunking between selective routers and PSAPs,
and upgrades to PSAP CPE to accommodate the extra ANI digits.
Cell Site
911
Selective Router
MSC
PSAP
ANI Controller
ESRD (pANI)
+ Callback #
ESRD (pANI)
+ Callback #
Workstation
ALI Controller
911
(Send)
Location
Info
ANI (TN)
Telephone
= Voice Path
= Data Path
PSAP's
PSAP's ALI
ALI
Call Path Associated Signaling (CAS)
PSAP Operations Guide for Wireless 9-1-1
10
Hybrid CAS
Hybrid CAS (HCAS) is a combination of CAS and NCAS call delivery. HCAS delivers the
call from the wireless carrier’s network to the 9-1-1 selective router in CAS (full 20
digits). At the router, the ESRD and callback number is sent to the ALI database where
ALI creates a temporary record, assigning a routing “key” to the record (the digits used
for the “key” vary by HCAS solution). The ESRD is used to look up the static location
information in ALI. This static location information is copied into the temporary record
along with the callback number. The SR then uses the key to deliver voice, over the
voice path, to the PSAP. The PSAP’s CPE then uses the “key” to query ALI and obtain
the callback and location information for the call.
This delivery solution is dependent upon the Local Exchange Carrier’s (LEC) or 9-1-1
service provider’s ability to implement the HCAS software solution within its network (on
both the Selective Router and ALI) and is not available in all areas.
Cell Site
911
Selective Router
MSC
PSAP
ANI Controller
ESRD (pANI)
+ Callback #
Key
(Callback #
or Call ID)
Workstation
ALI Controller
911
(Send)
Key
Location Info
(inc X,Y)
& Callback #
Key
Telephone
= Voice Path
ESRD & Callback #
= Data Path
PSAP's
PSAP's ALI
ALI
Phase I HCAS Call Flow
PSAP Operations Guide for Wireless 9-1-1
11
NCAS Solution with WID Device
The functionality of the selective router can be altered to accept twenty digits along the
voice path, but if the PSAP on the other end cannot accept the twenty digits, the router
must strip off half of those digits to complete the voice call to the PSAP. In some cases,
selective router functionality has been altered through either software or hardware
upgrades to perform this function. In other cases, a device generically referred to as a
wireless integration device (WID) is added into the network to perform this specialized
function. A WID can be used to accept 20 digits conveyed from the MSC; the 20 digits
are composed of the routing number and the caller’s 10-digit number. The WID converts
a 10-digit ESRD to an 8-digit ESRD that is then passed with the voice call to the
selective router. The WID device routes both the ESRD and the call-back number to the
ALI database where the ALI record is dynamically updated with the call-back number.
When the PSAP receives the voice call, the PSAP uses the ESRD to query for the ALI
record. In some cases—mainly related to the type of mobile switch used by the carrier—
wireless carriers can use this solution to affect only Phase I wireless deployment.
Specific technical details must be identified very early during deployment to ensure that
the appropriate equipment is available. WIDs can be deployed either by wireless carriers
or by LECs to resolve technical systems interface issues if necessary.
Similar to the NCAS solution described above, provisioning the ALI record supporting
this solution assumes that the caller’s call-back number may be dynamically inserted into
the ALI record at the time of the call. Information about the cell sector receiving the call
is built into an ALI record with the appropriate ESRD number as its lookup key.
Cell Site
911
Selective Router
MSC
PSAP
ANI Controller
Workstation
ESRD (pANI)
ESRD (pANI)
& Callback #
ALI Controller
ESRD
Location Info
(inc X,Y)
& Callback #
ESRD
(pANI)
911
(Send)
Telephone
WID
ESRD & Callback #
= Voice Path
PSAP's
PSAP's ALI
ALI
= Data Path
WID Solution NCAS
PSAP Operations Guide for Wireless 9-1-1
12
Summary
Each of the technology solutions described above represents a viable method to provide
the Phase I E9-1-1 data to the PSAP, taking into account the needs and capabilities of
the WSP, the LEC network, and the PSAP. The selection of the technological solution
used to deliver the required Phase I data to the PSAP is dependent upon existing E9-1-1
infrastructure, the technological capabilities of the WSP and the economic realities that
PSAPs face.
PHASE I—WHAT THE DISPATCHER SEES
The information displayed at the PSAP to the dispatcher may vary somewhat from the
traditional ALI screens, depending on the solution the WSP uses to deploy wireless
E9-1-1. Below are examples of the various call technologies. Please remember that
individual PSAP equipment may vary from these examples.
NCAS Call Display
In the NCAS delivery, the call is delivered over two paths. The voice over 9-1-1 trunks
and the data are retrieved over the ALI circuit or path, just as wireline calls are sent. The
ALI record is updated for every call with dynamic information. The ANI or call-back
number is displayed along with the identification or description of the cell site. The
routing number or ESRK is displayed in the LOC field. The NENA company ID for the
wireless carrier whose network is handling the call will also be displayed.
The figure below is an example of an NCAS call display.
(Dynamic Data in Red)
callback number
720-111-9600
ESN: 787
WIRELESS CARRIER NAME
cell sector location description
123 MAIN ST – N SECTOR
BOULDER PSAP MOBL/WRLS WIRELESS CARRIER ID
routing digit (ESRK/pANI)
LOC= 303 511-2345
BOULDER CO
WIRELESS - VERIFY
VERIFY
VERIFY
NCAS Call Display Example
PSAP Operations Guide for Wireless 9-1-1
13
CAS Call Display
In the CAS delivery, the call is delivered over a single path. The ANI or call-back number
is displayed along with the identification or description of the cell site. The routing
number or ESRD is displayed in the pilot number field. The NENA company ID for the
wireless carrier whose network is handling the call will also be displayed.
The figure below is an example of a CAS call display.
callb ack nu m ber
routing digit (ES R D /pAN I)
720-111-9600
303 511-2345 E S N : 787
W IR E LE S S C A R R IE R N A M E
cell sector tow er add ress
123 M A IN S T
B O U LD E R P S A P M O B L W IR E LE S S C A R R IE R
cell sector location description
LO C = N S ector
B O U LD E R C O
W IR E LE S S - V E R IF Y
V E R IF Y
V E R IF Y
ID
CAS Call Display Example
HCAS Call Display
The HCAS call is delivered using a combination of NCAS and CAS. From the 9-1-1
service provider’s selective router, the call is delivered to the PSAP over two paths. The
voice on the regular 9-1-1 trunks and the data are retrieved over the ALI circuit or path,
just as wireline calls are sent. The ALI record is updated for every call with dynamic
information. The ANI or call-back number is displayed along with the identification or
description of the cell site. The routing number or ESRD is displayed in the pilot number
field. The NENA company ID for the wireless carrier, whose network is handling the call,
will also be displayed.
The figure below is an example of an HCAS call display.
ca llb ack n u m b er
ro u tin g d ig it (E S R D /p A N I)
7 2 0 -1 1 1 -9 6 0 0
3 0 3 5 1 1 -2 3 4 5 E S N : 7 8 7
W IR E L E S S C A R R IE R N A M E
ce ll s ecto r lo c atio n d es crip tio n
1 2 3 M A IN S T – N S E C T O R
B O U L D E R P S A P M O B L /W R L S W IR E L E S S C A R R IE R ID
B O U LD E R C O
W IR E L E S S - V E R IF Y
V E R IF Y
V E R IF Y
Phase I – HCAS Call Display Example
PSAP Operations Guide for Wireless 9-1-1
14
PHASE II TECHNOLOGY OVERVIEW
Wireless Phase II requires that the specific location of the caller be delivered to the
PSAP in the form of earth coordinates, (latitude/longitude, or x,y). This phase requires
the incorporation of a positioning determining entity (PDE) into the wireless infrastructure
to determine and provide location information.
The FCC defines two types of PDE technology— network-based and handset-based.
Network-based means that the components needed to determine location are embedded
into the wireless E9-1-1 network, such as at the MSC and/or cell sites. Handset-based
means that some of the location technology is embedded into the wireless handset, such
as a Geographical Positioning System (GPS) chip or software modifications.
The FCC adopted accuracy and reliability requirements for ALI as part of its rules for
wireless carrier E9-1-1 service in CC Docket No. 94-102, Revision of the Commission’s
Rules to Ensure Compatibility with Enhanced 911 Emergency Calling Systems. Those
rules were adopted in 1996 and revised in the Third Report and Order in that docket
(released October 6, 1999). The revised rules set the following accuracy and reliability
requirements for E9-1-1 Phase II operations:
For network-based solutions: 100 meters for 67 percent of calls; 300 meters for
95 percent of calls;
For handset-based solutions: 50 meters for 67 percent of calls; 150 meters for 95
percent of calls.
Phase-in schedules for Phase II are incorporated in Section 20.18(g) of the
Commission’s Rules (47 C.F.R. § 20.18(g)
911
Selective Router
(ESNE)
Cell Site
MSC
PSAP
ANI Controller
ESRK
ESRK
Workstation
ALI Controller
= Voice Path
= Data Path
PO
ESRK
ORREQ
MSC, Cell, Callback #
E1
PDE
CRDB
SR
RE
TE
p
Q
)
,Y
(X
q
re
rte
s
o
P)
SA
(P
Location Info (inc X,Y)
Callback #
2
se
ha
(P
q ion
re at
n)
os loc
EQ atio
gp
SR loc
PO r
G st fo
e
qu
(re
911
(Send)
E3
orreq (response)- ESRK
2
Telephone
ESPOSREQ (query for locationinitial or update)
E2
MPC
esposreq (Phase I initial
and/or
Phase 2 location
PSAP's ALI
PSAP's
ALI
(ESME)
ANSI NCAS Phase II Wireless 9-1-1 Network Diagram
PSAP Operations Guide for Wireless 9-1-1
15
GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS
To provide a higher level of functionality for wireless services, there are some WSPs that
are moving to the next generation of technology called Global System for Mobile
Communications (GSM). The network components, functionality, and terminology
related to wireless 9-1-1 varies. The network configuration diagram for GSM (below)
identifies these differences. In many cases the positioning determining functionality for
this technology is embedded in both the wireless handset and the carrier’s network.
Because of complexities and the recent introduction of GSM in North America, the FCC
has provided a phased approach for accuracy and time to deployment. This information
is located on the FCC website at www.fcc.gov/911.
BSC
SMLC
911
Selective Router
(ESNE)
Ls
Cell Site
PSAP
ANI Controller
BTS
MSC
ESRK
ESRK
Workstation
ALI Controller
ESRK
Lg
Location Information
911
(Send)
Location Info (inc X,Y)
Callback #
ISUP Looparound
Routing Information
Telephone
ESPOSREQ (query for
locationinitial or update)
= Voice Path
= Data Path
GMLC
esposreq (Phase I initial
and/or
Phase 2 location
PSAP's ALI
PSAP's
ALI
(ESME)
GSM MAP NCAS Phase II
PSAP Operations Guide for Wireless 9-1-1
16
OTHER SOLUTIONS
There are other solutions, including HCAS for Phase II, that are not discussed in detail in
this document, but if you become aware that either a wireless carrier or LEC are
deploying these alternatives, you should become familiar with their network
configurations and functionality to understand how they operate. The following diagram
is a generic Phase II HCAS call flow.
911
Selective Router
(ESNE)
Cell Site
MSC
PSAP
ANI Controller
Key
(Callback #
or Call ID
ESRD
Callback #
Workstation
ALI Controller
Telephone
Key
Location Info
(inc X,Y)
Callback #
= Data Path
N
ES
= Voice Path
RD #
ES ack
llb
Ca
PDE
orreq (response)/
IAM Out
911
(Send)
2
se
ha
(P n
q io
n)
re at
EQ atio
os loc
gp
SR loc
PO r
G st fo
e
qu
(re
ORREQ/IAM In
2
E1
ESPOSREQ (query for
locationinitial or update)
MPC
esposreq (Phase I initial
and/or
Phase 2 location
PSAP's
ALI
PSAP's ALI
(ESME)
ANSI HCAS Phase II
ACCURACY TESTING AND VERIFICATION.
In April 2000, the FCC released the document Guidelines for Testing and Verifying the
Accuracy of Wireless E911 Location Systems (OET Bulletin No. 71). This document was
prepared as a guideline to provide assistance in determining whether PDEs comply with
the above accuracy standards set by the FCC. It addresses general principles related to
default fallback, uncompleted calls, and timing and also provides recommendations on
testing and verification methods, including empirical and predictive testing.
The Emergency Service Interconnection Forum (ESIF) Technical Report ATIS-05000,
High Level Requirements for Accuracy Testing Methodologies (May 11, 2004) provides
a common frame of reference that individual stakeholders can use to validate the
accuracy methodology of 911 location technologies. The document provides a set of
minimum requirements to which individual testing methodologies should comply.
PSAP Operations Guide for Wireless 9-1-1
17
PHASE II CALL ROUTING
Phase II solutions provide two alternative methods for determining the PSAP to which a
wireless 9-1-1 call will be routed. If x,y coordinates of the wireless phone placing the
emergency call are available within the requisite routing interval, those coordinates can
be used to determine the appropriate routing of the call. If the coordinates are not
available in time to route the call, the cell site/sector routing established for Phase I will
be used.
PHASE II—WHAT THE DISPATCHER SEES
The information displayed at the PSAP to the calltaker may vary somewhat from the
traditional ALI screens, depending on the solution the WSP uses to deploy wireless
E9-1-1. Below are examples of the various call technologies. Please remember that
individual PSAP equipment and ALI formats may vary from these examples.
In Phase II, as in Phase I, the ANI or call-back number is displayed along with the
identification or description of the cell site. In addition, the latitude and longitude are
delivered and can be plotted on the PSAP’s selected mapping system. Uncertainty and
Confidence are measures of the predicted accuracy of the delivered coordinate location
information and are not always available to the PSAP. The ESRD is typically displayed
in the LOC field. The NENA company ID for the wireless carrier, whose network is
handling the call, will also be displayed.
During the Phase I deployment, the PSAP’s wireless jurisdictional boundaries are
established. Phase II uses those boundaries to identify the appropriate PSAP to receive
the 9-1-1 call.
The figure below is an example of a typical Phase II data display.
callback number
(Dynamic Data in Red)
720-111-9600
ESN: 787
WIRELESS CARRIER NAME
cell sector text location description
123 MAIN ST - NE
(Phase I type information)
-104.548407 +39.356910
Uncertainty (meters)
Confidence factor (%)
COP 90
COF 45
BOULDER PSAP WPHII WIRELESS CARRIER ID
routing digit (ESRK/pANI)
LOC= 303 511-2345
BOULDER CO
WIRELESS – VERIFY
VERIFY
Longitude (X)
VERIFY
and latitude (Y)
Phase II Data Elements
PSAP Operations Guide for Wireless 9-1-1
18
LOCATION RE-QUERIES AND MID-CALL UPDATES
Location re-queries and mid-call updates are dependant on many factors. The PSAP will
need the capability to request a manual re-query in the following events:
The caller’s latitude/longitude (x,y) is unavailable at the time the call is delivered
to the PSAP.
To request a more accurate x,y if the uncertainty or confidence factor was at the
high end of the acceptable range.
The PSAP needs an updated location for the caller.
PSAP Operations Guide for Wireless 9-1-1
19
FREQUENTLY ASKED QUESTIONS
Q What is the difference between static and dynamic data in ALI records?
Static data is the data that is built into the ALI record and remains unchanged during
the 9-1-1-call process. Dynamic data is the information that is inserted into ALI
records at the time of a 9-1-1 call. Examples of dynamic data are Callback Number,
Cell Site Address and Location Coordinates (Latitude/Longitude). Dynamic data is
generally inserted into ALI by the means of an MPC, GMLC, gateway, a CAMA
conversion device—such as Proctor®, CML, WID, Cell Trace™—or a selective
router with added functionality.
Q Where will the callback number be displayed in the ALI record?
The host ALI provider, along with the PSAP, determines the placement of the
callback number. Considerations include ALI display format and capabilities and
available NENA-standard data fields in the ALI database. The callback number
location is ultimately determined by the LEC and/or PSAP but is typically placed in
the Loc field, the RCF field, or the TN field.
Q What is a cell sector?
Cell sites—or base stations—usually have one or more sectors or receiving
antennas (one sector is most common in rural areas where maximum coverage is
most desired; three or more sectors are common in urban areas where simultaneous
call volume is more of an issue). Each sector is a separate antenna—or an array of
antennas—that emits and retrieves radio frequency (RF) signals. Sectors of multiplesector sites typically send and receive RF signals from a particular direction and
have a coverage area shaped roughly like a slice of pie. In the case of Phase I,
identifying the directional orientation of the sector that is handling a 9-1-1 call can
help to identify caller location.
Q How does the cell site recognize the cell phone callback number and
pass it to the MSC?
When a cell phone is used to call 9-1-1, it sends out a radio frequency (RF) signal,
which is picked up or received by an antenna on a cell site. The cell site receives the
radio frequency signal and relays it to the MSC. The RF signal includes the
electronic serial number (ESN), which is a 32-bit number that is coded into the
wireless phone, and the callback number of the phone. The combination of the ESN
and callback number uniquely identifies the account number of the wireless phone
subscriber. Due to upcoming ESN number exhaust, manufacturers will be coding
wireless phones with a machine equipment identifier (MEID). MEIDs are 56 bits, 14
hexadecimal digits, and are much larger numbers than ESNs.
Q Will PSAPs need to spend money to upgrade their CPE for Phase I?
No. If your PSAP is already enhanced, Phase I service does not require any changes
to your CPE.
PSAP Operations Guide for Wireless 9-1-1
20
Q Can PSAPs receive Phase I if they are not enhanced?
No. Since current Phase I technologies require ANI delivery and ALI retrieval, the
PSAP must be part of an E9-1-1 wireline network. (According to the FCC's Report &
Order in Docket No. 94-102, the wireless carrier is not obligated to deliver Phase I
service unless the requesting PSAP is able to make use of the data elements to be
provided.)
Q What is the difference between an ESRD and an ESRK?
The emergency service routing digit (ESRD) is a routing number or group of
numbers assigned per cell site/sector. The ALI record for an ESRD contains a static
address field that defines the cell sector location to the PSAP and may be
dynamically updated with the callback number at the time of the call. In a CAS
environment, there is no update required in the ALI record because the callback
number arrives with the voice as part of a 20-digit ANI.
The emergency service routing key (ESRK) is also a routing number or group of
numbers, but the numbers are assigned on a per PSAP basis. The ALI record for an
ESRK may be dynamically updated with the address field and the callback number at
the time of the call. The ESRK lends itself to additional field updates for wireless
Phase II, where location coordinates will be identified and passed into the 9-1-1
system.
Q Where are the MSCs located?
The MSCs are part of the wireless network infrastructure and are located within the
wireless carrier’s facilities.
Q Wireless integration devices (WIDs), also known as Proctor boxes or
Cell Trace™ boxes, are called CML boxes at Bell South. What are these
devices?
WIDs are devices that handle a 20-digit signal and convert that signal to send it
along two separate paths to complete a wireless 9-1-1 call. CML Technologies is one
of the manufacturers who make one of these WID devices. Proctor and Associates is
another manufacturer of a WID device. Qwest uses the product name Cell Trace
when providing WID service for wireless 9-1-1.
PSAP Operations Guide for Wireless 9-1-1
21
GLOSSARY
This section provides the definitions and explanations of the terms, acronyms, and
abbreviations used within this document and the 9-1-1 Industry.
Term
Definition
ALI
Automatic Location Identification. A feature of E9-1-1 service that displays
the name and address associated with the number of the phone used to dial
9-1-1. A database managed by a database provider.
ALI Database
Host computer system that stores ALI records.
Alternate Routing
A feature of Enhanced 9-1-1. Allows E9-1-1 calls to be routed to a
designated alternate location if the 9-1-1 system malfunctions, or the primary
PSAP is unable to receive and process 9-1-1 calls.
ANI
Automatic Number Identification. A feature that displays, at the answering
point, the number of the phone from which the 9-1-1 call was placed. In the
wireless environment, ANI is the display of the Mobile Directory Number
(MDN).
ANSI
American National Standards Institute
CAS
Call-Path Associated Signaling. A term that describes data transmission or
signaling that occurs on the same channel as voice communication. In the
9-1-1 environment, CAS is associated with the transmission of the wireless
caller’s mobile directory number (MDN) along the same channel as the
caller’s voice.
CBN
Callback number. On a wireless E9-1-1 call this is the Mobile Directory
Number (MDN) that the PSAP would use to re-contact or callback the caller.
CDMA
Code Division Multiple Access as defined in IS-95. When a communication
channel is shared by spread spectrum transmitted each with a different
spreading code for the purpose of achieving multiple access. Spread
spectrum is a technique to spread a signal over a frequency band that is
larger than the signal being sent in order to gain interference immunity. This
is one of several ways wireless or cellular devices function.
Cell
Basic geographic unit assigned to a fixed location cellular transmitting and
receiving station.
Cell Face
See Cell Sector.
Cell Sector
Location
Information
Data that indicates the cell sector from which a 9-1-1 call has been placed.
Cell Sector
The geographical area served by a cell site is divided into coverage areas
of one or more sectors (receiving antennas). 1 sector (Omni) is common in
rural areas where maximum coverage is most desired; 3 or more sectors
are common in urban areas where call volume is more of an issue.
Cell Sector
Number
The unique numerical identification of a cell sector.
Cell Site
A radio transceiver base station that acts as a point of entry for calls from
wireless devices into the wireless carrier’s telecommunications network.
CLEC
Competitive Local Exchange Carrier.
PSAP Operations Guide for Wireless 9-1-1
22
Term
Definition
CLLI
Common Language Location Identifier. A Bellcore Standard code used to
identify a central office (CO) through the use of an 11-character code.
CMRS
Commercial Mobile Radio Service. This is the formal FCC classification of
wireless carriers.
CO – Central
Office
A telephone-switching center that contains the equipment to provide phone
service to users in a particular geographic area. A CO may serve more than
one prefix, or more than one CO located in the same building. Also known
as End Office, Control Office.
CPE
Customer Premise Equipment. Phone or terminal equipment located on the
customer’s premises. This equipment may be owned or provided by the
customer or a telephone company.
CRDB
Coordinate Routing Database.
Default Routing
A feature of Enhanced 9-1-1. Default routing occurs when a 9-1-1 call
cannot be selectively routed because the ANI signal is garbled or not
available to the tandem switch.
Directional
Antenna
An antenna or array of antenna designed to concentrate radio signal in a
particular area.
E2
Messaging protocol for transferal of ALI data for Phase II to send the x, y,
confidence, uncertainty, cell sector information.
ELT
English Language Translation. A database table in MS that provides the
names of the emergency service agencies associated with the
Administrative ESN. Both Intrado data analysts and the MSAG coordinator
are responsible for maintaining and updating ELTs.
EMF
Enhanced Multi Frequency. A voice path signaling protocol that allows the
transmission of up to 20 digits per call using Multi Frequency tones.
Enhanced 9-1-1
(E9-1-1)
Includes ANI and ALI features that display name, address or cell sector info,
and TN of 9-1-1 caller.
End Office
The telephone-switching center that initiates a 9-1-1 call. Also known as
CO.
ENP
Emergency Number Professional.
ESCO
Emergency Service Central Office Number. The information delivered to the
PSAP when there is an ANI failure between the end office and the 9-1-1
Control Office. When ANI is not available, the 9-1-1 call is default routed
and the ANI display at the PSAP will be "911-0TTT" (or 911-TTTT) with TTT
identifying the trunk group between the end office and the selective router
and therefore, the end office.
ESN
Emergency Service Number. A three to five digit alphanumeric code that
represents an emergency service zone. This number is used by selective
router to route E9-1-1 call to a particular PSAP.
ESPOSREQ
Request to the MPC or GMLC by the ESME for location information for the
wireless caller
esposreq
MPC/GMLC response to the ESME containing the wireless caller’s location
data
ESRD
Emergency Services Routing Digit. A 10-digit routable, but not necessarily
PSAP Operations Guide for Wireless 9-1-1
23
Term
Definition
dialable, number that is used for routing on a per origination cell sector
basis.
ESRK
10 digit routable, but not necessarily dialable, number that is used not only
for routing but also as a correlator, or key, for the mating of data that is
provided to a PSAP by different paths, such as via the voice path and ALI
data path. In daily use, the term ESRK is used to distinguish operational
environments where the “routing” digits are assigned on a per destination
PSAP basis as opposed to a per origination cell sector basis (which is the
strict technical definition of an ESRD).
Federal
Communications
Commission
(FCC) The United States agency, which is charged with licensing and
regulation of the wireless industry.
FCC NPRM
FCC Notice of Proposed Rule Making (NPRM) issued 10/94 -ensures
compatibility with E9-1-1 calling systems and is to be implemented in
phases:
Phase 0—The delivery of a voice call from a wireless device to a
PSAP.
Phase .5—Delivers the caller’s voice and call back number.
Phase I—Delivers the caller's voice, call back number, and cell site
sector information.
Phase II—Delivers Phase I info plus the Latitude and Longitude of the
caller (x, y)
First Office Application. The initial installation of an application into a
customer site.
FOA
Geo-code
The assignment of a geographic coordinate to a non-location value (e.g.,
street address to lat./long coordinate)
GIS
Geographic Information System
GMLC
Gateway Mobile Location Center
GPOSREQ
MPC’s request for the wireless caller’s X,Y from the PDE
gposreq
PDE’s response to the MPC containing the wireless caller’s X,Y
GPS
Global Positioning System
GSM
Global System for Mobile Communications. The standard digital phone
service offered in Europe and Japan. Some carriers in the United States are
also deploying this standard as well.
HCAS
Hybrid Call-path Associated Signaling
ILEC
Incumbent Local Exchange Carrier
IAM
Initial Address Message - ISUP
ISDN
Integrated Services Digital Network. A hierarchy of digital switching and
transmission systems synchronized so that all digital elements speak the
same language at the same speed. ISDN provides simultaneous voice and
digital transmission capabilities. A digital interface providing multiple
channels for simultaneous functions between the network and CPE.
LEC
Local Exchange Carrier.
LNP
Local Number Portability.
PSAP Operations Guide for Wireless 9-1-1
24
Term
Definition
MDN
Mobile Directory Number. A 10-digit directory number used to call a
wireless phone.
MIN
Mobile Identification Number. Key identification number assigned by the
cellular carrier to a cellular phone, paired with the electronic serial number
both numbers are verified for legitimate wireless call making.
MPC
Mobile Position Center. The MPC serves as the entity that retrieves,
forwards, stores, and controls position data within the location network. The
MPC receives and stores the position estimation for subsequent retrieval.
MS
Mobile Station
MSC
Mobile Switching Center. A switch that provides stored program control for
wireless call processing. Identifies the switching office that processes the
cellular call to the Public Switch Telephone Network (PSTN). SCC uses the
term MSC as per TR45.2, but “MTSO” and “MSO” also describe a mobile
switching center.
MSO
Mobile Switching Office. See MSC.
MTSO
Mobile Telephone Switching Office. See MSC.
NCAS
Non Call-Path Associated Signaling. A term that describes data
transmission or signaling that occurs on a separate channel than that which
transmits a voice communication. In the 9-1-1 environment, NCAS refers to
a wireless solution set that employs a signal control point (SCP) within a
wireless carrier network. The SCP has a software application installed to
provide dynamic update of several data fields during the course of a 9-1-1
call event. The NCAS solution set permits PSAPs to receive ANI and ALI
information relating to a wireless voice call via separate data channels, thus
permitting the continued use of CAMA lines. The solution set requires that
routing numbers (ESRD/K) be built following the relationship of trunk
capacity to each PSAP being deployed.
OREQ or ORREQ
Origination Request message sent to the MPC by the MSC
pALI
Pseudo ALI (Automatic Location Identification). In the Wireless 9-1-1
application, this is the ALI for the pANI. pANI is used to route the call to the
appropriate PSAP, not a call-back number to reconnect with the caller.
pANI
Pseudo ANI (Automatic Number Identification). In the Wireless 9-1-1
application, this is the ANI for the pANI. pANI is used to route the call to the
appropriate PSAP, not a call-back number to reconnect with the caller.
PDE
Position Determining Entity. The PDE determines the precise position or
geographic location of a wireless terminal when the MS starts a call or while
the MS is engaged in a call. Each PDE supports one or more position
determining technologies.
POSRTEREQ
MPC’s request from CRDB for a number associated with a PSAP for routing
purposes.’ The MPC provides the wireless caller’s X,Y to the CRDB.
posrtereq
CRDB response to the MPC containing a number associated with a PSAP
for the purposes of routing the wireless caller’s emergency call.
PS/ALI
Private Switch/Automatic Location Information: The process of providing
ALI information for access lines located within a PBX environment. In this
process, the private switch must provide data to the 9-1-1 system to identify
the locations of 9-1-1 calls placed through the switch.
PSAP Operations Guide for Wireless 9-1-1
25
Term
Definition
PSAP
Public Safety Answering Point. A facility equipped and staffed to receive 91-1 calls. A Primary PSAP receives the calls directly. If the call is relayed or
transferred, the next receiving PSAP is designated a Secondary PSAP.
PSTN
Public Switched Telephone Network. The network of equipment, lines, and
controls assembled to establish communication paths between calling and
called parties in N. America. The phone system, including the Network.
Routing Number
A number used to facilitate the routing and delivery of a wireless 911 call.
Routing numbers are assigned both in quantity and configuration,
dependent upon the solution set employed. See also ESRD and ESRK.
Rehome
The process of relocating the records that serves a specific geographic area
from one switch to another. Rehoming typically affects MSCs and Selective
Routers.
RF
Radio Frequency.
SALI
Stand-alone ALI. An ALI database, which is maintained locally at the PSAP
on-premise or at a telephone company’s central or regional office.
SCP
Service Control Point. A centralized database system used for, among other
things, wireless E9-1-1 service applications. It specifies the routing of 9-1-1
calls from the cell site to the PSAP. The SCP contains special software and
data that includes all relevant cell site location and cell sector identifiers.
SCPs contain centralized network databases for providing enhanced
services. The SCP accepts queries from a STP and returns the requested
information to the originator of the query. They provide the core database
and call processing functions on which telecommunications services are
based. A remote database within the SS7 network that supplies the
translation and routing data needed to deliver advanced network services.
Identifies cell sites sending 9-1-1 calls to the 9-1-1 network. Part of the SS7
network that determines where the call should be connected according to
the digits dialed – usually a database with routing and control information.
Also referred to as a Signal Control Point.
Secondary PSAP
A PSAP that only receives emergency calls from the 9-1-1 network as a
result of a transfer. 9-1-1 calls are not routed to secondary PSAPs.
SR or Selective
Routing
Selective Router. A switch that provides the feature in which 9-1-1 calls
from a central office area that is served by more than one PSAP are
electronically routed to the proper PSAP. The combination of the Routing
ESN and the customer location information accomplish this.
SR / ALI
Selective Router Automatic Location Information. An SCC proprietary
product that allows compatible selective routers to query the ALI database
for routing instructions.
STP
Signal Transfer Point. The packet switch in the Common Channel Interoffice
Signaling (CCIS) system.
TDMA
Time Division Multiple Access. A digital (usually radio) system that allows a
number of users to use the same system by being dynamically assigned a
particular timeslot on request.
TDOA
Time Difference of Arrival. A method of location determination using the
time differences at which the radio signal arrives at multiple sites or
antennas in a network.
PSAP Operations Guide for Wireless 9-1-1
26
Term
Definition
TN
Telephone Number. Unique combination of ten digits that identifies the
equipment used to place and receive calls.
Trunk
A network communication path connecting two switching systems. A
Central Office circuit terminating in the telephone equipment on the
customer’s premises. A circuit between CO and the PSAP.
WID
Wireless Integration Device. A device that performs a protocol conversion
function to allow for transport of wireless data into the 9-1-1 system without
modifying existing selective routers or PSAP CPE.
WIN
Wireless Intelligent Network. Term used by cellular carriers in the wireless
industry. SS7 based, Standardization Activity (IS-53), MIN Based value
added services.
Wireless
A set of radio-based telecommunications services including cellular, paging,
PCS and other mobile radio
services. A technology that combines the
use of radio frequency and hard wired telephone networks to allow voice
and/or data communications from, to and between devices that are, may, or
may not be hard wired to the public switched telephone network.
WSP
Wireless Service Provider.
PSAP Operations Guide for Wireless 9-1-1
27
