ETSI TS 101 314 V4.1.1 (2003-09)

Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON) Release 4; Abstract Architecture and Reference Points Definition; Network Architecture and Reference Points

RTS/TIPHON-02009R4

Harmonizacija telekomunikacij in internetnega protokola prek omrežij (TIPHON), 4. izdaja - Abstraktna arhitektura in definicija referenčnih točk - Arhitektura omrežja in referenčne točke

General Information

• Status: Published
• Publication Date: 03-Sep-2003
• Technical Committee: TIPHON 2 - TIPHON Architecture models and interfaces
• Current Stage: 12 - Completion
• Due Date: 01-Aug-2003
• Completion Date: 04-Sep-2003
• Ref Project: SIST-TS TS 101 314 V4.1.1:2004 - Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON) Release 4; Abstract Architecture and Reference Points Definition; Network Architecture and Reference Points

Standards Content (Sample)

SLOVENSKI STANDARD
01-april-2004
+DUPRQL]DFLMDWHOHNRPXQLNDFLMLQLQWHUQHWQHJDSURWRNRODSUHNRPUHåLM7,3+21
L]GDMD$EVWUDNWQDDUKLWHNWXUDLQGHILQLFLMDUHIHUHQþQLKWRþN$UKLWHNWXUDRPUHåMD
LQUHIHUHQþQHWRþNH
Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON)
Release 4; Abstract Architecture and Reference Points Definition; Network Architecture
and Reference Points
Ta slovenski standard je istoveten z: TS 101 314 Version 4.1.1
ICS:
33.020 Telekomunikacije na splošno Telecommunications in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

Technical Specification
Telecommunications and Internet Protocol
Harmonization Over Networks (TIPHON) Release 4;
Abstract Architecture and Reference Points Definition;
Network Architecture and Reference Points

2 ETSI TS 101 314 V4.1.1 (2003-09)

Reference
RTS/TIPHON-02009R4
Keywords
architecture, internet, IP, telephony, VoIP
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© European Telecommunications Standards Institute 2003.
All rights reserved.
TM TM TM
DECT , PLUGTESTS and UMTS are Trade Marks of ETSI registered for the benefit of its Members.
TM
TIPHON and the TIPHON logo are Trade Marks currently being registered by ETSI for the benefit of its Members.
TM
3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners.
ETSI
3 ETSI TS 101 314 V4.1.1 (2003-09)
Contents
Intellectual Property Rights.5
Foreword.5
Introduction .5
1 Scope.6
2 References.6
3 Definitions and abbreviations.7
3.1 Definitions.7
3.2 Abbreviations.9
4 Basic concepts.10
4.1 Functional planes.10
4.2 Domains and functional groups.11
5 Functional decomposition of the IP telephony application plane.12
5.1 Introduction to the functional layers.12
5.1.1 The services functional layer .13
5.1.2 The service control functional layer .14
5.1.3 The call control functional layer.15
5.1.4 The bearer control functional layer.16
5.1.5 The media control functional layer .16
5.2 Definition of reference points.17
5.2.1 SC-Service reference points.18
5.2.2 SC-SC reference points.19
5.2.3 CC-SC reference points .19
5.2.4 CC/BC-CC/BC reference points .19
5.2.5 MC-BC reference points.19
5.2.6 MC-MC reference points .19
5.2.7 TR-MC reference points .20
5.2.8 Call unrelated reference point configurations .20
5.2.8.1 Registration.20
5.2.9 Call-related reference point configurations.20
5.2.9.1 Scenario 0.20
5.2.9.1.1 Users at home .21
5.2.9.1.2 Roaming users.21
5.2.9.2 Scenario 1.22
5.2.9.2.1 User at home.23
5.2.9.2.2 Roaming user.24
5.2.9.3 Scenario 2.24
5.2.9.3.1 User at home.25
5.2.9.3.2 Roaming user.26
5.2.9.4 Scenario 3.27
6 Functional decomposition of the IP transport plane.27
6.1 Introduction to the transport functional layers.28
6.1.1 Transport service functional layer .28
6.1.2 Transport control layer.28
6.1.3 Transport flow layer.29
6.2 Definition of reference point .29
6.2.1 Transport control - transport service reference points .29
6.2.2 Transport control - transport control reference points .30
6.2.3 Transport flow - transport control reference points .30
7 Management plane.30
7.1 Functional decomposition of the management plane .30
7.1.1 Management functional architecture.30
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4 ETSI TS 101 314 V4.1.1 (2003-09)
7.1.2 Management information architecture.33
7.1.3 Management physical architecture .33
7.2 Management processes.34
7.2.1 Flow-though process model.34
7.3 Interconnection between management plane and TIPHON planes .35
8 Architecture summary.36
Annex A (informative): Business roles reference configuration.37
History .39

ETSI
5 ETSI TS 101 314 V4.1.1 (2003-09)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Project Telecommunications and Internet Protocol
Harmonization Over Networks (TIPHON).
Introduction
The present document describes the network architecture and the reference configurations that are necessary for the
support of services and service capabilities defined for TIPHON Release 4. The TIPHON Release 4 definition and the
corresponding relationship between the core deliverables is described in TR 101 301 V4.1.1 [1].
The present document builds upon the concepts embodied in TIPHON Release 3 [8]. These concepts which are
applicable to network configurations based on the range of functional and entities within the IP network, as described in
the present document that are necessary to support the four scenarios of TIPHON Release 4.
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6 ETSI TS 101 314 V4.1.1 (2003-09)
1 Scope
The present document defines the TIPHON network architecture and the reference configurations that are necessary for:
• the delivery of telephone calls, which originate and terminate in IP networks;
• the delivery of telephone calls which originate in an Internet Protocol (IP) network and are delivered to
Switched Circuit Networks (SCN);
• the delivery of telephone calls which originate in SCNs and are delivered in an IP network; and
• the delivery of telephone calls which originate in SCNs, routed through IP networks and delivered to SCN.
These four scenarios are part of TIPHON Release 4.
The architecture includes provision of information and facilities which are incidental to the delivery of telephone calls
described above. The present document builds upon the concepts embodied in the TIPHON Release 3 network
architecture and reference configurations described in TR 101 877 [8]. The present document is applicable to equipment
fulfilling the roles of the functional groups identified in TS 101 878 [2]; Terminal functional group, network functional
group and Gateway functional group, and also to entities within the IP network that are necessary to support the four
scenarios of TIPHON Release 4.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
[1] ETSI TR 101 301: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Release Definition; TIPHON Release 3 Definition".
[2] ETSI TS 101 878: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Service Capability Definition; Service Capabilities for a simple call".
[3] ETSI TS 101 329-2: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; End-to-end Quality of Service in TIPHON Systems; Part 2: Definition of
Speech Quality of Service (QoS) Classes".
[4] ETSI TS 101 871 (all parts): "Digital Enhanced Cordless Telecommunications (DECT);
Application Specific Access Profile (ASAP); DECT Multimedia Access Profile (DMAP); Profile
requirement list and profile specific Implementation Conformance Statement (ICS) proforma".
[5] ETSI TR 101 303: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Requirements definition study; Introduction to service and network
management".
[6] ETSI TR 101 311: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Service Independent requirements definition; Transport Plane".
[7] Void.
ETSI
7 ETSI TS 101 314 V4.1.1 (2003-09)
[8] ETSI TR 101 877: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON); Requirements Definition Study; Scope and Requirements for a Simple call".
[9] Void.
[10] ETSI TS 101 303: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 4; Service Independent Requirements Definition; Service and Network
Management Framework; Part 1: Overview and Introduction".
[11] ITU-T Recommendation M.3010: "Principles for a Telecommunications management network".
[12] ITU Recommendations M.3200: "TMN management services and telecommunications managed
areas: overview".
[13] ITU Recommendations M.3400: "TMN Management Functions".
[14] GB910: "Telecom Operations Map".
[15] GB921 June 1: "enhanced Telecom Operations Map (eTOM): The Business Process Framework-
for the Information and Communications Services Industry".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
administrative domain: collection of physical or functional entities under the control of a single administration
aggregate bearer: logical association of functional entities in an IP telephony application and transport network which
creates one or more concurrent end to end media flows and which is not limited to the duration of a single call
Aggregate Bearer Admission Control (ABAC) function: functional entity that determines whether or not a flow is to
be admitted as part of an established aggregate bearer
Aggregate Bearer Measurement (ABM) function: function that determines the capacity used and remaining in an
aggregate bearer as a result of measuring the actual media flows after taking into account what flows were requested
application data: media or signalling information content
bearer: logical association of functional entities in an IP telephony application and transport network which creates an
end to end media flow for no longer than the duration of a call
domain: collection of physical or functional entities within an administrative domain which share a consistent set of
policies and common technologies
Domain IDentifier (DID): globally unique identifier of a domain. Domain identifiers may be mapped to the IP
Telephony Administrative Domain (ITAD) Numbers, registered by IANA and used by the TRIP Protocol
end-user: entity using the services of an IP telephony service provider or transport network operator
end-user domain: collection of physical or functional entities under the control of an end-user which share a consistent
set of policies and common technologies
functional entity: entity in a system that performs a specific set of functions
Functional Group (FG): collection of functional entities within a domain.
NOTE: In TIPHON systems functional groups are used to structure the necessary functionality to offer IP
telephony services across domains
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8 ETSI TS 101 314 V4.1.1 (2003-09)
gateway functional group: functional group containing the functionality of a network functional group also the
functionality necessary to connect calls to the SCN
NOTE: Gateway functional groups may be classified as originating or terminating based upon their location
within the topology of a specified call.
home network functional group: functional group, which is aware of the service application subscribed to by the
end-user
NOTE: Home network functional groups may be classified as originating or terminating based upon their location
within the topology of a specified call.
intermediate (transit) network functional group: functional group connecting the serving network functional group
to the home network functional group
NOTE: The intermediate network functional grouping is only present when the serving network functional
grouping and the home network functional grouping are not directly connected.
information flow: interaction between a communicating pair of functional entities
interconnection function: functional entity connecting two networks having differing administrative policy such as
Quality of Service (QoS) or addressing policy but employing the same signalling protocol, and transport technology, at
the point of interconnect
interface: shared boundary between two communicating systems, devices or equipment
IP network: packet transport network comprising one or more transport domains each employing the IP protocol
IP telephony: any telephony related service that is supported on a managed IP network
IP telephony service provider: service provider who offers IP telephony services
NOTE: The same business entity may act as both a transport network operator and an IP telephony service
provider.
network functional group: functional group containing the functionality required to establish a call between two
terminals, a gateway and a terminal, or two gateways
NOTE: Network functional groups may be classified as originating or terminating based upon their location
within the topology of a specified call.
packet flow/transport flow: stream of packets of the same type identified by common address and port numbers
NOTE: The stream may contain either signalling information or content description together with media
information.
protocol: set of semantics, syntax and procedures, which govern the exchange of information across an interface
reference point: conceptual point at the conjunction of two communicating functional entities
service domain: collection of physical or functional entities offering IP telephony services under the control of an IP
telephony service provider which share a consistent set of policies and common technologies
serving network functional group: functional group that enables terminal functional groups to connect to an IP
telephony service provide
Switched Circuit Network (SCN): telecommunications network, e.g. Public Switched Telephone Network (PSTN),
Integrated Services Digital Network (ISDN), and General System for Mobile communications (GSM), that uses
circuit-switched technologies for the support of voice calls
NOTE: The SCN may be a public network or a private network.
terminal: endpoint within the user equipment on which signalling and media flows originate and/or terminate
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9 ETSI TS 101 314 V4.1.1 (2003-09)
terminal functional group: functional group representing all the IP telephony functionality within an end-user's
terminal
NOTE: Terminal functional groups may be classified as originating or terminating based upon their location
within the topology of a specified call.
ticket: a ticket is obtained through the registration session, when used in a call it provides the terminal/user with a
means to show a valid registration exists
transport domain: collection of transport resources sharing a common set of policies, QoS mechanisms and transport
technologies under the control of a transport network operator
transport function: functional entity representing the collection of transport resources within a transport domain which
are capable of control by a transport resource manager
transport network: collection of transport resources, which provide IP transport functionality
transport network operator: business entity operating a transport network
transport policy entity: functional entity that maintains the policies of a transport domain
Transport Resource Manager (TRM): functional entity that applies a set of policies and mechanisms to a set of
transport resources to ensure that those resources are allocated such that they are sufficient to enable transport flows
with QoS guarantees across the domain of control of the TRM
user equipment: equipment under the control of an end-user
user profile: service specific information about a user of a service application
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ABAC Aggregate Bearer Admission Control
ABM Aggregate Bearer Management
BC Bearer Control
CC Call Control
CR Call Routing function
DID Domain IDentifier
DiffServ Differentiated Services
DNS Domain Name Service
DTMF Dual Tone Multi Frequency
FCAPS Fault, Configuration, Accounting, Performance and Security
FG Functional Group
GSM General System for Mobile communication
HREG Home network REGistration function
IANA Internet Assigned Numbers Authority
ICF Interconnect Function
IP Internet Protocol
IPTN IP Telephony Network
IREG Intermediate Network Registration function
ISDN Integrated Service Digital Network
ITAD IP Telephony Administrative Domain
MC Media Control
MD Mediation Device
MPLS Multi-Protocol Label Switching
NE Network Element
NEF Network Element Function
OAM&P Operation Adminstration Maintenance & Provision
OS Operations System
OSF Operations System Function
PSTN Public Switched Telephony Network
QoS Quality of Service
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10 ETSI TS 101 314 V4.1.1 (2003-09)
QoSM Quality of Service Management
QoSP Quality of Service Policy
SC Service Control
SCN Switched Circuit Networks
SpoA Service point of Attachment
SREG Service Network REGistration function
TA Transport Accounting function
TOM Telecommunications operations Map
TF Transport Function
TP Transport Policy
TREG Terminal Registration function
TRIP Telephony Routing over IP Protocol
TRM Transport Resource Management
WS Work Station
WSF Work Station Function
4 Basic concepts
4.1 Functional planes
TR 101 877 [8] describes an environment for communications services that encompasses multiple domains of control
and technology.
Figure 1 expands upon [8] by identifying the following functional planes, each containing a high level grouping of
functionality:
• IP telephony application;
• IP transport;
• SCN;
• management.
SCN plane
IP Telephony Application plane
Management
plane
Transport plane (including IP)

Figure 1: Functional planes
The SCN plane contains the functionality relating to the SCN. Part of the SCN plane is a component of the service
abstraction layer as defined in [8], and part of the SCN plane is a component of the transport abstraction layer as
defined in [8]. Architectures for SCNs are defined elsewhere, therefore, details of this functional plane are not
considered further in the present document.
The IP telephony application plane makes use of capabilities provided by the other functional planes and it contains
functions to support telephony. The IP telephony application plane is a component of the service abstraction layer as
defined in [8]. The IP telephony application plane contains functions and has information flows that support the service
capabilities defined in [2].
ETSI
Security
Quality of Service
Network Management
11 ETSI TS 101 314 V4.1.1 (2003-09)
The transport plane (including IP) contains the functionality relating to the underlying packet transport and services in
general use, e.g. DNS. The IP transport plane is a component of the transport abstraction layer as defined in [8].
The management plane contains the management functionality relating to QoS, security and network management. The
details of this functional plane are considered in [5].
4.2 Domains and functional groups
TS 101 878 [2] defines a number of concepts and terms that are used in the present document.
Domains are a collection of physical entities or functional entities under the control of a single administration which
shares a consistent set of policies and compatible technologies.
TIPHON distinguishes three kinds of domains: end-user domains, service domains and transport domain.
The end-user domain is controlled by the end-user, the service domain is controlled by an IP telephony service provider
and the transport domain is controlled by a transport network operator.
Functional groups are the constructs used in the present document to structure functionality necessary to offer IP
telephony services across domains. The mapping between domains and functional groups is shown in [2].
NOTE: There may not be a one-to-one mapping between application level domains and transport level domains.
The following functional groups are identified in the end-user domain:
• terminal functional group: a functional group representing all the IP telephony functionality within a user's
terminal. Terminal functional groups may be classified as originating or terminating based upon their location
within the topology of a specified call;
• terminal registration functional group: a functional group representing the registration within the user's
terminal.
The following functional groups are identified in the service domain:
• network functional group: a functional group containing the functionality required to establish a call between
two terminals, a gateway and a terminal or two gateways. network functional groups may be classified as
originating or terminating based upon their location within the topology of a specified call;
• Gateway Functional Group: a functional group containing the functionality of a network functional group. It
also has the functionality necessary to connect calls between IP and SCN domains. Gateway functional groups
may be classified as originating or terminating based upon their location within the topology of a specified
call.
The network functional group represents all of the functionality of an application to support a call. In fixed network
environments, the originating end-user always has a contract with the service provider controlling the service domain
containing the originating network functional group. The terminating user has a contract with the service provider
controlling the service domain containing the terminating network functional group. For mobility considerations this
may not be the case.
Although the network functional groups may contain an application plane and a transport plane, no description is
provided on how (and if) this domain is related to transport functional groups. No further description of this domain is
given in this clause, although details of the functional groups in the transport domain are identified later in the present
document.
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12 ETSI TS 101 314 V4.1.1 (2003-09)
Network functional groups are further divided into serving network functional group, intermediate network Functional
group and home network functional groups. These are defined as:
• serving network functional group: a functional group that enables terminal functional groups to connect to a
service provider (home network functional group). Serving network functional groups may be classified as
originating or terminating based upon their location within the topology of a specified call;
• intermediate (transit) network functional group: a functional group that connects the serving network
functional group to the home network functional group or between originating and terminating home network
functional groups. The intermediate network functional group is only present when the serving network
functional group and the home network functional group are not directly connected. There may be more than
one intermediate network functional groups supporting communications between serving and home network
functional group;
• home network functional group: a functional group, which is aware of the service applications, subscribed
by the end-user. Home network functional groups may be classified as originating or terminating based upon
their location within the topology of a specified call.
The home network functional group and the serving network functional group may reside in the same network or in
different networks.
Figure 2 depicts all the TIPHON functional groups identified in this clause.
Originating
Terminating
Originating Terminating Terminating
Originating Intermediate Intermediate Intermediate
Serving Serving
Terminal Network Home Network Home Network Terminal
Network Network
FG FG FG FG
FG FG FG
FG FG
Figure 2: TIPHON functional groups
5 Functional decomposition of the IP telephony
application plane
The architecture for the IP telephony application plane implements the capabilities necessary for the IP telephony
application.
The IP telephony application architecture is described using objects. These objects are related to each other but may be
instantiated and deleted separately.
One or more objects, taken together, exhibit the behaviour of the functional entities described in the present document.
The functionality in the IP telephony application plane is distributed within functional layers based on an object's
lifetime and object's ownership. Each functional layer provides capabilities to adjacent layers. This grouping is useful to
understand the functionality involved but does not imply any physical implementation.
Where there is a requirement for an interface between functional entities, a reference point is defined.
5.1 Introduction to the functional layers
The IP telephony application plane has 5 functional layers: the services functional layer, the service control functional
layer, the call control functional layer, the bearer control functional layer and the media functional layer.
These functional layers are shown in figure 3. For simplicity only two functions are shown in each functional layer with
all of the possible communication paths within the functional layer and to the adjacent functional layers.
ETSI
13 ETSI TS 101 314 V4.1.1 (2003-09)

Services
Service
Control
Call
Control
Bearer
Control
Media
Control
Figure 3: Functional layers in the IP telephony application plane
Each of the functional layers is introduced in the subsequent clauses.
5.1.1 The services functional layer
The services functional layer contains the collections of data and associated logic (e.g. scripts) that produce service
functions. The services functional layer is related to the service and registration capabilities identified in [2]. A service
capability may use more than one function in the Services functional layer and functions in other layers.
NOTE 1: The collections of data and logic (service functions) may be held in different places and may be owned
and run by service providers who create services over networks run by other parties. These service
functions may interact with each other to control registration and calls.
Call related service functions are accessed by the call control functional layer through the services control functional
layer. Registration related functions, are accessed by the service control functional layer.
NOTE 2: The following illustrates the operation of the call control functional layer, the service control functional
layer and the services functional layer. When a caller requests a call, the call control layer interrogates the
services functional layer (via the service control functional layer) for the caller's profile and any other
service functions needed. Using this information, the call control functional layer sends a request for a
call towards the called party. This request may be modified by an intermediate network (e.g. re-routed)
but eventually arrives at the call control functional layer of the called party. This call control functional
layer interrogates the called user's profile and other relevant service functions and determines whether or
not the call can be accepted and if not what response should be provided.
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14 ETSI TS 101 314 V4.1.1 (2003-09)
This functional layer has the following functions:

User-service profile function This function is present in a terminal registration functional group. It provides
information required for registration and stores information received during
registration (user-related information pertaining to the services the user wants
to register for as well as information on the service provider with whom the
service shall be registered).
It provides, on request, information needed for call establishment (such as
authorization information and user preferences).
The lifetime of this information is valid as long as the user has the contract with
the service provider this service profile refers to.

User profile function This function is present in the home network functional group. It holds
information about the user.
The lifetime of this information is valid as long as the user has the contract with
the service provider this service profile refers to.

Call Routing (CR) function This function is present in any network functional group. It provides
address/number translation, number length determination and telephony
routing capabilities.
This function will exist as long as the service provider exists. The lifetime of the
information contained in this function is as long as the call routing information is
valid.
Accounting function This function is present in any network functional group. It handles and stores
call and service related information. The stored information may be used for
billing the user or other operators.
This function will exist as long as the service provider exists. The lifetime of
information in this function is at least as long as the legal time to keep such
information.
QoS Policy (QoSP) function This function is present in any network functional group. It manages IP
telephony QoS policies and provides authorization of permitted and default
QoS levels.
This function will exist as long as the service provider exists. The lifetime of
information in this function is as long as the QoS policies stay the same.

5.1.2 The service control functional layer
The service control functional layer provides two classes of functions:
• management of registrations; and
• support for calls.
To manage registrations, this layer:
• receives information from the terminal about the user and generates requests for authentication from its own
services functional layer or a remote services functional layer via a peer service control functional layer; and
• processes the responses from the services functional layer and generates authorization "tickets" that are stored
in the user's terminal. These tickets are then used with call requests.
To support calls, this layer:
• receives requests from the call control functional layer and generates requests for information to the
appropriate services functions, which may be local or remote and may also be provided by third parties; and
• processes the responses from the service functions to produce and return responses to call control.
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15 ETSI TS 101 314 V4.1.1 (2003-09)
The service control functional layer is related to service capabilities and registration capabilities identified in [2]. A
service capability may use more than one function in the service control functional layer and functions at other layers.
This functional layer has the following functions:

This function is present in any network functional group. It provides
support for calls by accessing information at the services layer. This
support mainly concerns authorization and routing, including name and
Service Control (SC) function
address translations.
This function exists as long as the service provider provides this type of
service application.
This function is present in terminal registration functional group. It
Terminal Registration (TREG) function registers a user at a terminal with a service provider. This function lives
as long as the user has a registration session with the network.

Service Network Registration (SREG) This function is present in the serving network functional group. It
function
accepts registration of a user at a terminal.
This function exists as long as the user has a registration session with
the network.
Intermediate Network Registration (IREG) This function is present in the intermediate network functional group. It
function
accepts registration requests from user at a terminal via the serving
network functional group and proxies the request towards the home
network functional group.
This function exists as long as the user has a registration session with
the network.
Home Network Registration (HREG) function This function is present in the home network functional group. It accepts
registration of a user at a terminal.
This function exists as long as the user has a registration session with
the network.
5.1.3 The call control functional layer
The call control functional layer shall maintain a call context. The call context allows the bearer control functional
layer to provide the connections and capabilities requested by the user (as permitted by the service provider). In order to
achieve this control, the call control functional layer may request information from the service control functional layer.
The call control functional layer is related to the service and registration capabilities identified in [2]. A service
capability may use more than one function in the call control functional layer and functions at other layers.
This functional layer has the following functions:

Call Control (CC) function This function is present in any network functional group. It maintains the
call state and, if present, provides services that change the call state
e.g. call forwarding, call transfer and conferencing. This function has the
same lifetime as the call it controls.
Communication with peer call control functions for the establishment and
release of calls.
Requests services from functions in the service control functional layer.
Request determination of, allocation of, and release of, resources from
bearer control functions.
ETSI
16 ETSI TS 101 314 V4.1.1 (2003-09)
5.1.4 The bearer control functional layer
The bearer control functional layer manages the logical association between pairs of endpoints. Bearer control shall
be responsible for mapping call topology to individual media flows (e.g. connect parties a, b and c together). These
flows may be between any pair of media processing functions in the media functional layer.
The bearer control functional layer is related to the service and registration capabilities identified in [2]. A service
capability may use more than one function in the bearer control functional layer and functions at other layers.
This layer has the following functions:

This function is present in any network functional group. It allows or
Bearer Control (BC) function disallows media streaming based on information from call control. This
function has the same lifetime as the bearer that it controls.
Bear
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