ISO/IEC TR 16167:2011

Information technology — Telecommunications and information exchange between systems — Next Generation Corporate Networks (NGCN) — Emergency calls

ISO/IEC TR 16167:2011 discusses issues related to emergency calls from an enterprise user to a safety answering point (SAP) using the Session Initiation Protocol (SIP) within a Next Generation Corporate Network (NGCN). A SAP can be either a public safety answering point (PSAP) or a private emergency answering point (PEAP). ISO/IEC TR 16167:2011 uses terminology and concepts developed in ISO/IEC TR 12860. It identifies a number of requirements impacting Next Generation Network standardization and concerning deployment of enterprise networks. The scope of ISO/IEC TR 16167:2011 is limited to calls from a user of an enterprise network to an authority, where the authority is represented by a SAP (PSAP or PEAP). This includes the special case where a PEAP acts as an enterprise user in making an emergency call to a PSAP. Authority to authority calls, authority to enterprise user calls and enterprise user to enterprise user calls within the context of an emergency are out of scope, with the exception of return calls and verification calls as follow-up to an emergency call from the user to an authority.

Technologies de l'information — Téléinformatique — Réseaux d'entreprise de prochaine génération (NGCN) — Appels d'urgence

General Information

• Status: Published
• Publication Date: 31-Aug-2011
• ICS: 35.110 - Networking
• Technical Committee: ISO/IEC JTC 1/SC 6 - Telecommunications and information exchange between systems
• Drafting Committee: ISO/IEC JTC 1/SC 6 - Telecommunications and information exchange between systems
• Current Stage: 6060 - International Standard published
• Due Date: 06-Apr-2012
• Completion Date: 01-Sep-2011

Relations

• Revises: ISO/IEC TR 16167:2010 - Information technology — Telecommunications and information exchange between systems — Next Generation Corporate Networks (NGCN) — Emergency calls
• Effective Date: 15-Jan-2011

Standards Content (Sample)

TECHNICAL ISO/IEC
REPORT TR
16167
Second edition
2011-09-01


Information technology —
Telecommunications and information
exchange between systems — Next
Generation Corporate Networks
(NGCN) — Emergency calls
Technologies de l'information — Téléinformatique — Réseaux
d'entreprise de prochaine génération (NGCN) — Appels d'urgence




Reference number
ISO/IEC TR 16167:2011(E)
©
ISO/IEC 2011

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ISO/IEC TR 16167:2011(E)

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©  ISO/IEC 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
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ISO/IEC TR 16167:2011(E)
Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Normative references . 2
3  Terms and definitions . 2
3.1  External definitions . 2
3.2  Other definitions . 2
4  Abbreviations . 3
5  Background . 5
6  Technical aspects of emergency calls in enterprise networks . 8
6.1  Identifying a call as an emergency call . 8
6.1.1  User actions . 8
6.1.2  Signalling impact . 10
6.1.3  Unauthenticated access . 12
6.2  Obtaining and delivering the location of the caller . 12
6.2.1  Format of location information . 13
6.2.2  Obtaining location information for delivery . 13
6.2.3  Location conveyance in SIP . 18
6.3  Routing an emergency call to the appropriate SAP . 18
6.3.1  Routing by the calling device . 19
6.3.2  Routing by enterprise SIP intermediary . 20
6.4  Delivering information to the SAP to allow a return call or verification call to be made . 21
6.4.1  Delivery of caller identification . 21
6.4.2  Delivery of device identification . 21
6.4.3  Identifying a return call or verification call . 22
6.5  Ensuring appropriate resources are available for an emergency call, return call or
verification call . 22
6.6  Ensuring appropriate media quality during an emergency call . 23
6.7  Security considerations . 24
6.8  Other aspects . 25
6.8.1  Hosted users . 25
6.8.2  Guest users . 25
7  NGN considerations . 25
8  Device considerations . 27
9  Alternatives for roaming mobile and nomadic users . 28
9.1  Establishing an emergency call when already signalling via a visited public network . 28
9.2  Establishing an emergency call via a visited public network when other traffic is signalled
directly via the enterprise network . 29
9.3  Establishing an emergency call directly to a PSAP . 29
10  Enterprise responsibilities . 29
11  Summary of requirements and standardisation gaps . 30
11.1  Requirements on NGNs . 30
11.2  Recommendations on enterprise networks . 30
11.3  Standardisation gaps . 31
Bibliography . 32

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ISO/IEC TR 16167:2011(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
In exceptional circumstances, when the joint technical committee has collected data of a different kind from
that which is normally published as an International Standard (“state of the art”, for example), it may decide to
publish a Technical Report. A Technical Report is entirely informative in nature and shall be subject to review
every five years in the same manner as an International Standard.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC TR 16167 was prepared by Ecma International (as ECMA TR/101) and was adopted, under a special
“fast-track procedure”, by Joint Technical Committee ISO/IEC JTC 1, Information technology, in parallel with
its approval by national bodies of ISO and IEC.
This second edition cancels and replaces the first edition (ISO/IEC TR 16167:2010), which has been
technically revised. This second edition makes a distinction between an answering point and an emergency
control centre and clarifies a few other points, in particular to do with interaction with (public) Next Generation
Networks.

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ISO/IEC TR 16167:2011(E)
Introduction
This Technical Report is one of a series of publications that provides an overview of IP-based enterprise
communication involving Corporate telecommunication Networks (CNs) (also known as enterprise networks)
and in particular Next Generation Corporate Networks (NGCN). The series particularly focuses on session
level communication based on the Session Initiation Protocol (SIP) [5], with an emphasis on inter-domain
communication. This includes communication between parts of the same enterprise (on dedicated
infrastructures and/or hosted), between enterprises and between enterprises and public networks. Particular
consideration is given to Next Generation Networks (NGN) as public networks and as providers of hosted
enterprise capabilities. Key technical issues are investigated, current standardisation work and gaps in this
area are identified, and a number of requirements are stated. Among other uses, this series of publications
can act as a reference for other standardisation bodies working in this field.
Various regional and national bodies address emergency communications, mainly with an emphasis on public
telecommunications. In particular, in the United States work is carried out by the National Emergency Number
Association (NENA). In Europe, ETSI EMTEL (Special Committee on Emergency Communications) plays a
coordinating role, liaising with external bodies (e.g., in the European Commission, CEPT, CEN and
CENELEC) as well as overseeing work done by other ETSI Technical Bodies (e.g., TISPAN). This Technical
Report focuses on emergency calls as they impact enterprise networks, and therefore is intended to
complement the work of those other bodies.
This Technical Report is based upon the practical experience of Ecma member companies and the results of
their active and continuous participation in the work of ISO/IEC JTC 1, ITU-T, ETSI, IETF and other
international and national standardisation bodies. It represents a pragmatic and widely based consensus. In
particular, Ecma acknowledges valuable input from experts in ETSI TISPAN, ETSI EMTEL, 3GPP CT1 and
IETF ECRIT.

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TECHNICAL REPORT ISO/IEC TR 16167:2011(E)

Information technology — Telecommunications and information
exchange between systems — Next Generation Corporate
Networks (NGCN) — Emergency calls
1 Scope
This Technical Report discusses issues related to emergency calls from an enterprise user to a safety
answering point (SAP) using the Session Initiation Protocol (SIP) within a Next Generation Corporate Network
(NGCN). A SAP can be either a public safety answering point (PSAP) or a private emergency answering point
(PEAP). This Technical Report uses terminology and concepts developed in ISO/IEC TR 12860. It identifies a
number of requirements impacting Next Generation Network (NGN) standardisation and concerning
deployment of enterprise networks.
The scope of this Technical Report is limited to calls from a user of an enterprise network to an authority,
where the authority is represented by a SAP (PSAP or PEAP). This includes the special case where a PEAP
acts as an enterprise user in making an emergency call to a PSAP. Authority to authority calls, authority to
enterprise user calls and enterprise user to enterprise user calls within the context of an emergency are out of
scope, with the exception of return calls and verification calls as follow-up to an emergency call from the user
to an authority.
This Technical Report focuses on emergency calls within a SIP-based NGCN using geographic location
information to indicate the whereabouts of the caller. Emergency calls can originate from devices connected to
the NGCN via various access technologies, e.g., SIP over fixed or wireless LAN (Local Area Network), TDM
(Time Division Multiplex) networks, DECT (Digital Enhanced Cordless Telephone) networks, PMR (Private
Mobile Radio) networks, PLMN (Public Land Mobile Network), etc. SAPs are assumed to be reachable either
directly using SIP or via a gateway to some legacy technology (e.g., TDM). Furthermore, SAPs are assumed
to be reachable either directly from the NGCN or via a public network accessed from the NGCN using SIP. In
the latter case, the NGCN might identify the SAP and instruct the public network to route to the SAP, or
alternatively the NGCN might leave the public network to identify the SAP, based on the location of the caller.
In all cases the NGCN is assumed to deliver the location of the caller to the SAP, gateway or public network in
order to provide appropriate information to the call taker at the SAP.
The handling of incoming emergency calls at a SAP, even when the SAP is provided within an NGCN, is
outside the scope of this Technical Report. This includes the case where a PSAP is provided within an NGCN
and hence the NGCN can receive emergency calls from public networks. This also includes the case where a
PEAP is provided within an NGCN and can receive emergency calls from other enterprise networks or other
parts of the same NGCN.
Different territories have different regulations impacting emergency calls, together with national or regional
standards in support of these regulations. This Technical Report takes a general approach, which should be
largely applicable to any territory. However, detailed differences might apply in some territories, e.g., country-
or region-specific dial strings used to identify emergency calls.
The scope of this Technical Report is limited to emergency communications with a real-time element,
including but not limited to voice, video, real-time text and instant messaging. The focus, however, is on voice,
which in the majority of situations is likely to be the most effective medium for emergency calls. However, it is
recognised that some users with special needs will require other modes of communication (e.g., real-time text,
fax), as discussed in Annex B of [29], and also different modes can be used for the emergency call and the
verification call. The focus is also on calls in which the caller is a human user. There may also be applications
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ISO/IEC TR 16167:2011(E)
where automatic sensors can make similar emergency calls (subject to regulation), but the special needs of
such applications are not considered.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC TR 12860, Information technology — Telecommunications and information exchange between
systems — Next Generation Corporate Networks (NGCN) — General
3 Terms and definitions
3.1 External definitions
For the purposes of this document, the following terms defined in ISO/IEC TR 12860 apply:
 Domain
 Enterprise network
 Next Generation Corporate Network (NGCN)
 Next Generation Network (NGN)
 Private network traffic
 SIP intermediary
3.2 Other definitions
For the purposes of this document, the following terms and definitions apply.
3.2.1
authority
organisation mandated to receive and respond to reports from individuals of emergency situations involving
danger to person or property
3.2.2
emergency call
call from an enterprise user to a private authority or public authority for the purpose of reporting an emergency
situation involving danger to person or property
3.2.3
emergency control centre
ECC
facilities used by emergency organisations to handle rescue actions in answer to emergency calls
NOTE This definition is taken from [29].
3.2.4
location
geographic location
geographic position of an entity, in the form of either geospatial coordinates (latitude, longitude, altitude) or a
civic address
NOTE A civic address can extend to internal landmarks within a site, e.g., building number, floor number, room
number.
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ISO/IEC TR 16167:2011(E)
3.2.5
location information
location or information from which a location can be derived
3.2.6
private authority
authority mandated by one or more enterprises to receive and respond to reports of emergency situations
from enterprise users
3.2.7
private emergency answering point
PEAP
SAP established by a private authority for accepting and responding to emergency calls from users of one or
more enterprise networks
3.2.8
public authority
authority mandated to receive and respond to reports of emergency situations from the general public
(including enterprises)
3.2.9
public safety answering point
PSAP
SAP established by a public authority for accepting and responding to emergency calls from the general public
(including enterprises)
NOTE The term PSAP is defined by the IETF in RFC 5012 [14]. The definition above is used in this Technical Report
to stress the difference between a PSAP and a PEAP.
3.2.10
return call
call from a SAP to a caller or device that recently made an emergency call
3.2.11
safety answering point
SAP
answering point established by an authority for the purpose of accepting and responding to emergency calls
3.2.12
verification call
call from a SAP to a person or device that can assist in verifying conditions reported during a recent
emergency call
NOTE Verification calls are frequently used when emergency calls have been made by sensor devices. For example,
a verification call could be to another device in the vicinity, such as a camera.
4 Abbreviations
A-GPS Assisted GPS
AOR Address Of Record
ALI Automatic Location Identification
CSTA Computer Supported Telecommunications Applications
DHCP Dynamic Host Configuration Protocol
DoS Denial of Service
ECRIT Emergency Context Resolution with Internet Technologies
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ISO/IEC TR 16167:2011(E)
ELIN Emergency Location Identification Number
ECC Emergency Control Centre
E-CSCF Emergency Call Session Control Function
GPS Global Positioning System
HELD HTTP Enabled Location Discovery
HTTP Hyper-Text Transfer Protocol
IBCF Interconnection Border Control Function
IMS IP Multimedia Subsystem
IP Internet Protocol
LAN Local Area Network
LbyR Location by Reference
LbyV Location by Value
LCP Location Configuration Protocol
LIS Location Information Service
LLDP Link Layer Discovery Protocol
LLDP-MED LLDP Media Endpoint Discovery
LoST Location-to-Service Translation
NAT Network Address Translator
NGCN Next Generation Corporate Network
NGN Next Generation Network
PAI P-Asserted-Identity
P-CSCF Proxy Call Session Control Function
PEAP Private Emergency Answering Point
PIDF Presence Information Data Format
PIDF-LO PIDF Location Object
PLMN Public Land Mobile Network
PSAP Public Safety Answering Point
PSTN Public Switched Telephone Network
SAP Safety Answering Point
SIM Subscriber Identity Module
SIP Session Initiation Protocol
TDM Time Division Multiplex
TLS Transport Layer Security
UA User Agent
UAC User Agent Client
UAS User Agent Server
URI Universal Resource Identifier
URN Universal Resource Name
VoIP Voice over IP
VPN Virtual Private Network
WLAN Wireless LAN
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ISO/IEC TR 16167:2011(E)
5 Background
General concepts of NGCNs are discussed in ISO/IEC TR 12860. In particular, that document describes use
of the Session Initiation Protocol (SIP) [5] for session level communications within enterprise networks and
with other domains. It focuses on enterprise networks based on enterprise infrastructure (NGCN), but also
covers hosting on other networks, in particular NGNs, using the same infrastructure that supports public
networks.
One important use of session level communications is for making an emergency call from an enterprise user
to an authority for the purpose of reporting an emergency situation involving danger to person or property. The
authority responds typically by dispatching appropriate resources to deal with the situation, perhaps first
having taken steps to verify the situation. The authority concerned can be a private authority, dealing with
emergency situations involving enterprise personnel or property, or can be a public authority, perhaps
established by local or national government and having jurisdiction throughout a fixed geographic area or
entire country. A private authority will be concerned only with emergencies arising on premises of the
enterprise(s) concerned and perhaps off-premises emergencies involving enterprise personnel or property
(e.g., company vehicles). Hence a private authority only handles calls from users of one or more enterprises.
On the other hand, public authorities will be concerned with emergencies arising anywhere within the
geographic area concerned and will handle emergency calls from the general public, including from
enterprises when the emergency is not to be handled by an enterprise authority.
An authority responsible for emergency calls will establish one or more safety answering points (SAP) for
answering emergency calls. A private authority will establish a private emergency answering point (PEAP)
accessible from the enterprise network(s) concerned, whereas a public authority will establish a public safety
answering point (PSAP) reachable from public networks. Emergency calls from enterprise users to SAPs are
analogous to citizen to authority calls in public telecommunications. When the SAP is a PSAP, an emergency
call from an enterprise user is indeed a citizen to authority call.
A SAP will interact with one or more emergency control centres (ECC) for initiating and controlling rescue
actions in answer to emergency calls. However, ECCs, and interactions between SAPs and ECCs, are
outside the scope of this Technical Report.
Figure 1 shows an example of an emergency call from an enterprise user to a PSAP (which will forward
information about the emergency to an appropriate ECC).
Enterprise network Public network
Enterprise PSAP ECC
user
Direction of call establishment

Figure 1 — Example of an emergency call from an enterprise user to a PSAP
Figure 2 shows an example of an emergency call from an enterprise user to a PEAP accessible from the
enterprise network.
Enterprise network
Enterprise PEAP ECC
user
Direction of call establishment

Figure 2 — Example of an emergency call from an enterprise user to a PEAP
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ISO/IEC TR 16167:2011(E)
A PEAP will typically cover only one or a limited number of sites, and is unlikely to cover sites in different
countries. Thus a large enterprise might have several PEAPs. Not all enterprises will operate their own SAPs,
and some might operate SAPs only for large or specialised campuses, and not for smaller sites. For example,
a chemical factory or airport might operate its own PEAP, which might be better equipped than a PSAP for
dispatching specialist units for dealing with the most likely emergencies. Also a very large but non-specialised
campus might operate its own PEAP, which might be better equipped in terms of local knowledge, local
evacuation procedures or local medical or fire-fighting equipment that can reach the scene of the emergency
more quickly. Similarly a hotel might have local procedures and limited equipment for fire fighting, for example.
A PEAP might not handle all types of emergency, some being deferred by the PEAP to a PSAP. An enterprise
user might even be allowed to select between calling the PEAP or calling a PSAP. Smaller enterprises, and
smaller outposts of large enterprises (e.g., local sales offices) are far less likely to operate their own PEAPs.
Furthermore, a single private authority might be responsible for receiving and responding to emergency calls
from a number of enterprises. One example is a business park or office block occupied by a number of
enterprises and providing a common PEAP. Another example is a hosting organisation that provides
communications infrastructure for a number of tenants, together with a common PEAP. Logically, each
enterprise has its own PEAP, but physically they are shared. A further consequence is that a PEAP might be
outside the enterprise network that it serves. As a result, emergency calls from one enterprise to a PEAP in
another enterprise might traverse public networks, which will not necessarily recognise emergency call traffic
and provide special treatment.
An emergency call originated by the user of an enterprise network has to be routed to the appropriate SAP,
whether this be a PEAP or a PSAP. The appropriate SAP may depend on the caller's location as well as on
enterprise policy and possibly on the caller's preference. Also it is important to deliver to the SAP the location
of the caller and information to facilitate making a return call. Resources need to be made available to
emergency calls to ensure an extremely high probability of success. An emergency call needs to be subject to
certain constraints, in terms of codecs used, whether voice activity detection is active, etc. Finally, there are
security considerations.
Perhaps the single most difficult issue is how to deal with roaming users, accessing the enterprise network
from outside company premises, potentially anywhere in the world. For these users, connecting to a PEAP
within their normal enterprise site or to a PSAP in their home city or country often makes no sense. This and
other issues are discussed in the remainder of this Technical Report.
NOTE An emergency call from a user who is geographically on enterprise premises but connected directly to a public
network (e.g., a Public Land Mobile Network (PLMN)) (and not connected via Virtual Private Network (VPN) with the
enterprise network) will be routed to a PSAP. The possibility for a public network to detect that a user is on enterprise
premises and route an emergency call to the enterprise network for further handling (e.g., routing to a PEAP) is not
regarded as feasible. This possibility is not considered further in this Technical Report.
Where a PEAP is unable to handle an emergency call itself, it will need to make emergency calls to a PSAP or
to another PEAP. For this purpose the PEAP can be regarded as an enterprise user, and hence such a call is
might be treated as just another emergency call from an enterprise user to a SAP. In another sense it is an
authority-to-authority call, and may require different treatment, e.g., it might be awarded higher priority for
access to resources, and might not be subject to any restrictions on call hold or premature disconnection.
Such calls are within the scope of this Technical Report only when treated as ordinary emergency calls from
an enterprise user. Figure 3 shows an example.
Enterprise network Public network
PSAP ECC
st nd
Enterprise
Direction of 1 call establishment Direction of 2 call establishment
PEAP
user

Figure 3 — Example of an emergency call from an enterprise user to a PEAP, resulting in a second
emergency call from the PEAP to a PSAP
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