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- Mobile Radio Networks: Networking and Protocols. Bernhard H. Walke
Copyright©1999 John Wiley & Sons Ltd
ISBNs: 0-471-97595-8 (Hardback); 0-470-84193-1 (Electronic)
15
UPT—Universal Personal
Telecommunication∗
People are becoming more mobile. At the same time they have a greater need
to be reachable and to be able to reach others. A variety of different systems
that address all the different categories of mobility already exist:
• Employees can be reached through a DECT terminal anywhere in their
company.
• Tradesmen can be called over a Digital Communication System (DCS)
within a city.
• Business people can be reached over the same telephone number via
GSM anywhere in Europe, wherever they are located.
• Adventurous types are linked to civilization through the INMARSAT
satellite system.
For each of these communications systems, the user requires a special terminal.
In contrast to these radio-based systems, wireline telecommunications sys-
tems capable of reaching almost every household in the industrialized countries
are available. Fixed networks do not offer users mobility. To be reached at
another terminal, the user has to inform the caller of his new location area in
the form of a telephone number. With Universal Personal Telecommunication
(UPT) the telecommunications network assumes responsibility for establish-
ing a user’s location through an interrogation of databases based on a personal
telephone number. This provides mobility in telecommunications networks to
a larger number of users without the need for special new terminals.
15.1 Classification of Telecommunications
Services
The services of a telecommunications network first allow users to exchange
information over the network in order to communicate. A service is what is
∗ With the collaboration of Matthias Fr¨hlich
o
- 774 15 UPT—Universal Personal Telecommunication
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Figure 15.1: Classification of telecommunications services
made available to users by telecommunications authorities and private service
providers for communication over public and private networks.
The ITU-T distinguishes [20] between two types of service:
Bearer services, also called communications services, are used to transfer
data between precisely defined user–network interfaces. According to
the ISO/OSI reference model, a bearer service is provided by layers 1–3
(the Open Systems Interconnection reference model (OSI-RM, [6, 25])
of the ISO (International Organization for Standardization) describes
communication between open systems as seven interrelated layers). An
example of this is the socalled B-channel in ISDN with 64 kbit/s of
transmission capacity.
Teleservices offer users the possibility of communicating with one another
over network terminals, and are provided by layers 1–7 of the OSI-RM.
This also specifies the communications functions of the terminals. An
example of this is the telephone service in ISDN.
With both services a separate distinction is made between interactive ser-
vices and distribution services, which are subdivided further as shown in Fig-
ure 15.1.
Services are described according to the service features offered to the user.
A differentiation is made between general connection features, basic service
features and extended service features (see Figure 15.2).
Extended service features are only available in connection with a bearer
or teleservice, and can be provided either outside of the network or within
the network. Within the network they are subject to standardization and are
specifically referred to as supplementary services (see Figure 15.3).
Value-added services (VAS) are extended service features that are provided
by service nodes outside the network in OSI layers 4–7. These services usually
contain storage, call-up or conversion functions for interfaces, protocols and
- 15.2 Extended Service Features in ISDN and GSM 775
General
connection features Service-
specific Fast connection setup
Special call completion
Barring
Subscriber Supplementary Connection-
Special lines
service features service features specific
Charge display
Information- Supplementary information
Basic specific Operations advice and dictionary
service features Number identification
Figure 15.2: Breakdown of the service features of telecommunications services
Supplementary service features
Available only together with
bearer services or teleservices
Additional services Value-added services
Provision inside Provision outside
the network defined the network
by standards non-standardized
Figure 15.3: Separation of supplementary service features into additional and
value-added services
bit-rate adaptation. They require an interface to a bearer or teleservice of the
network.
Figure 15.4 presents a breakdown of the bearer services, teleservices, sup-
plementary services and value-added services in a telecommunications net-
work, with S representing the access interface of the user between terminal
and network and Q the interface between value-added service and network.
15.2 Extended Service Features in ISDN and
GSM
The current worldwide success of GSM is due to a great extent to the sup-
plementary and value-added services offered. Owing to the harmonization
between ISDN and GSM, most of the extended service features of ISDN are
also available in GSM. The following section describes the most important
supplementary and value-added services of ISDN. The service features offered
additionally by GSM will be described in Section 15.2.2.
- 776 15 UPT—Universal Personal Telecommunication
Service Module
Q Value-added Service
Transport Network,
Ter- e.g., ISDN Ter-
Supplementary minal Function for minal
Service S Supplementary S
Service
Bearer Service
Teleservice
Figure 15.4: Breakdown of bearer services, teleservices, supplementary services
and value-added services
15.2.1 Supplementary and Value-Added Services in ISDN
Because of full digitalization of its network, ISDN offers a variety of supple-
mentary services compared with the analogue telephone network, the most
important of which can be summarized into seven groups:
Number identification displays the telephone number of the party calling
or of the party being called. The latter is of interest, for example,
when call diversion is being activated. There are ways of keeping these
supplementary services secret. In addition, more than one telephone
number can be supported on one connection.
Call diversion allows an incoming call to be diverted immediately to another
number after a brief wait or if a number is busy.
Special call completion includes supplementary service features such as call
holding for enquiries as well as automatic callback or call-waiting if the
number called is busy.
Group connections include conference and three-party calls as well as calls
for closed user groups.
Charge functions allow to bill all or some incoming calls to the called sub-
scribers account and to display the charges for these calls.
Supplementary information can be exchanged between the terminals using
transparent user signalling.
Barring functions can be used for suppressing unwanted incoming calls, as
well as for restricting specific or all outgoing calls.
For the first time, some of the supplementary and value-added services
of ISDN are supporting the mobility of users, or, in other words, a person-
alization of the services is offered. Thus, for example, call diversion allows
- 15.2 Extended Service Features in ISDN and GSM 777
incoming calls to be routed to another location, thereby supporting the user’s
mobility. Personalization is provided to a limited degree through the exclusive
assignment of multiple-access telephone numbers to specific groups of people
or the barring of certain telephone numbers for incoming calls.
15.2.2 Supplementary and Value-Added Services in GSM
Depending on the system, GSM offers several extended service features that
are not supported by ISDN. In particular, these are services that support
mobility and personalization directly through the system. The main ones
include the following:
Device mobility, i.e., the ability to move freely within the radio coverage area
of a base station during a call. Because the radio connection is switched
automatically (handover ), it is even possible to change between any
number of adjacent base stations without causing an existing connection
to be broken off.
Authentication of the user, i.e., establishing and checking the identity in-
dependently of the terminal used. A Personal Identification Module
(PIM), usually in the form of a smart card, is used along with a Per-
sonal Identification Number (PIN).
Localization describes the automatic identification and storage of a user’s
location area in the network. This allows the user to be reached under
his GSM telephone number irrespective of his location.
Registration means making available the services subscribed to within the
framework of the contract agreed between operator and user (service
profile). The costs that are incurred are charged at the same time to
the user in accordance with the terms of the agreement. The subscriber’s
identity must be clearly established through the authentication process
in order to prevent fraudulent use.
Personalization of the service profile allows the user to configure certain ser-
vice features individually within the framework of the agreed service
agreement. Thus, for example, the user could activate or deactivate a
voice mail service (automatic answering service in the network) or re-
strict his own accessibility by blocking incoming calls because of the
extra cost these would occur or to avoid being disturbed.
The large number of users subscribing to the GSM network underline the
demand for these extended service features, so an effort is being made to
support them also in the fixed network—wherever this would be technically
feasible. The first step in this direction is the service referred to as Universal
Personal Telecommunication (UPT), which is introduced below.
- 778 15 UPT—Universal Personal Telecommunication
15.3 The UPT Service for Universal Personal
Telecommunication
The UPT service has been under development since the early 1990s, and
was standardized in its outline form through international recommendations
[21, 24] of the ITU in 1993. The introduction of the UPT service will take
place in several stages, and to date only the first (Capability Set 1 ) has been
standardized [26].
In wireline telecommunications networks such as ISDN the telephone num-
ber of a user is firmly linked to the network connection of the terminal. All
services of the network accessed from this network connection are charged to
the user. This fixed relationship between network connection and telephone
number of the user will be eliminated with the UPT service.
Identification of UPT users is carried out independently of the terminal
addressing and the access points of the network. A unique UPT number
allows a user to make and receive calls at any access point and from any
terminal in the network.
A telecommunications network must offer different supplementary services
in order to support the UPT service:
Personal mobility, which allows a UPT user to make and receive calls us-
ing different terminals in accordance with his service agreement (UPT
User’s Service Profile).
Identification of UPT users on the basis of network-independent UPT num-
bers.
Charging and billing, which is based on the UPT number independently of
the terminal.
Uniform access and authentication functions for UPT services in different
networks.
Security functions for protecting the personal data of UPT users.
Configuration functions, which are used by the UPT user and the UPT sub-
scriber to tailor the subscribed services to meet individual requirements.
The UPT service of the first phase offers these supplementary services in a lim-
ited form, and only supports the telephone service in the analogue telephone
network, in ISDN and in mobile radio networks. Other restrictions affect
the scope of the security functions as well as the access and authentication
functions.
These supplementary services will be available during the second phase in
a less restricted form and, e.g., data services will be supported. However, this
phase has not yet been standardized.
- 15.3 The UPT Service for Universal Personal Telecommunication 779
15.3.1 Existing Studies of the UPT Service
The mobile radio system UMTS (Universal Mobile Telecommunications Sys-
tem) [2, 29] is being designed to support standardized personalized worldwide
user telephone numbers and supplementary services similar to those of the
UPT service. Concepts for user administration in UMTS using a distributed
database are being developed [28] and quantitively evaluated on the basis of
models. Flat directory hierarchies used in connection with the interrogation
technique passing are proving to be particularly favourable.
The extended service features of ISDN such as call diversion and num-
ber identification enable services similar to those of UPT to be implemented
through a PC connected to the network access interface of the user. This
kind of system is being developed [27] and evaluated on a simulated basis.
For comparison purposes, several alternatives to UPT implementations are
being simulated and studied in the Deutsche Telekom network. The imple-
mentation with a PC at the network access interface of the user is showing
clear advantages in terms of waiting times for requested services. However,
this does not offer a complete UPT service, because the system does not sup-
port UPT calls from non-UPT terminals.
15.3.2 Further Development of UPT
The introduction of UPT into existing telecommunications networks is a dy-
namic development process. The fundamental objectives mentioned in Sec-
tion 15.3 are to be seen as guidelines that should be considered in any further
development of UPT [30].
Figure 15.5 shows the phases projected in the development of UPT. These
show a differentiation between essential and optional service features. Es-
sential service features must be available at the outset of the corresponding
development phase, whereas the offering of optional service features depends
on the decisions made by the UPT provider. A certain proportion of the ser-
vice features in both groups have already been standardized. The others have
already been developed to a degree and are awaiting future standardization.
15.3.3 Phase 1—Scenario with Limited UPT Functionality
During the introductory phase, UPT is limiting itself to PSTN (Public
Switched Telephone Network ), ISDN (Integrated Services Digital Network )
and possibly the Public Mobile Telephone Service. Only voice telephone ser-
vices are being offered. UPT phase 1 does offer limited service features for
security and user-friendliness. According to the projected plan, the first phase
has been completed at the end of 1993. UPT phase 1 functions are already
available in the IN operating tests being conducted worldwide. Phase 1 is to
be carried out without any intervention in existing networks, if possible.
- 780 15 UPT—Universal Personal Telecommunication
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Figure 15.5: Timetable for the development and standardization of UPT service
features
15.3.4 Phase 2—Scenario with UPT Basic Functionality
Phase 2 does offer UPT subscribers additional service features and supports a
larger number of networks. During this phase, UPT also linked up with GSM
networks and connection-oriented data networks. Smart cards and card read-
ers offer users improved security against fraudulent use by outsiders. Phase 2,
which was completed in 1995, is using the technology of intelligent networks.
15.3.5 Phase 3—Scenario with Extended UPT
Functionality
Phase 3 is offering extended UPT functionality. This phase was not specified
in detail, but only regarded as a target for UPT to allow a more effective
integration of new technological developments and an opportunity to respond
to the economic developments of UPT services. Phase 3 results were projected
for late 1997, and are available since then.
15.3.6 Service Features of UPT in Phase 1 of its
Introduction
As already explained, the ITU-T is considering some of the service features are
being essential and others as being optional. Four service features in phase 1
are essential for the implementation of UPT [21]:
- 15.4 Business Relationship between UPT Users and Providers 781
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Figure 15.6: Business relationshipment between conventional telephone subscriber
and system provider
• Authentication of a UPT user’s identity protects both the UPT provider
and the user from unauthorized use of the UPT service.
• In-call registration enables a UPT user to notify the network of the
location area where he can be reached through a terminal. This regis-
tration can be restricted to a specific period of time or revoked through
an explicit deregistration or new registration. It is possible for several
subscribers to be registered at the same terminal.
• An outgoing UPT call allows a UPT user to use a terminal and have the
call charged to his bill. So long as no follow-on service feature is avail-
able, an authentication must be carried out for each UPT call in order
to prevent fraudulent use. The service feature follow indicates to the
network that other calls are following the outcalls. New authentication
is then not necessary.
• In-call delivery refers to the call forwarding service. The UPT subscriber
makes his location known to the network beforehand through an in-call
registration. The incoming call is then forwarded to this terminal. The
subscriber to the network connection must be able to prevent registra-
tion and call forwarding at his terminal.
Access to UPT functions using registration is shown in Section 15.4.2.
15.4 Business Relationship between UPT Users
and Providers
To be able to use the telecommunications services, users must enter into a
business relationship with the provider.
Three different market participants can be identified in the conventional
monopolistic telecommunications market. Figure 15.6 identifies these three
business partners as:
- 782 15 UPT—Universal Personal Telecommunication
Service Provider
(Tele-, Supplementary, Value-added
Services)
UPT Service Provider Network Operator
Subscriber (UPT + Framework Service) (Bearer Services)
User Access Provider
Figure 15.7: UPT business relationships
• The network operator who provides network access and the communi-
cations network
• The subscriber to the service
• The service provider of the applications who contributes to the value-
added service in the network
The user has a direct business relationship with the network operator.
With UPT there is a complicated situation from the view of the user (see
Figure 15.7). In addition to
• a network operator, a user and an applications service provider,
there are also
• a UPT service provider, a network access provider and a subscriber to
the UPT services
who are involved in the UPT service arrangements.
A business relationship no longer exists between subscriber and network
operator. Instead, a subscriber can order the UPT services from a UPT
service provider. In the case of private individuals, this subscriber will be
the user himself. With companies, the organization appears as the subscriber
to the UPT services that it makes available to its employees through proper
registration in the user service profile. Since users usually do not use their own
terminals (mobility), it is important that a relationship exists with a network
access provider who can provide access to the network.
A deregulation of the telecommunications market is necessary in order to
enable the relationship between user and network operator to be split up.
A similar situation was observed with the mobile radio networks in Europe,
where users acquire mobile radio services from a service provider. The service
provider is not automatically also the network operator.
- 15.4 Business Relationship between UPT Users and Providers 783
15.4.1 Charging—New Concepts in the Introduction of
UPT
In conventional telecommunications networks the person placing a call is
charged for the duration of a successfully completed call, depending on time
of day and distance between user A and user B.
With UPT, users do not have to be registered at their home locations, and
instead may be linked to the network at location C. Users placing a call are not
aware of the distance between home location B and visitor location C. There-
fore they have no way of estimating how much a call will cost unless additional
information is provided. The following scenarios are therefore possible
• User A absorbs all the costs of the call, in other words connections A–B
as well as B–C.
• User A pays the cost of the connection A–B. User B pays the cost for
his mobility and consequently the cost of connection B–C.
• User B absorbs all the costs.
The second solution is the one that would appear to be ideal, because the costs
of the extended connection are charged to the person who is responsible for
the higher cost. Other solutions are conceivable for determining the charges;
however, cost transparency is important for the acceptance of new services so
that users have an easy way of estimating the costs of the calls they initiate.
With UPT it may be necessary also to charge the UPT user for calls that
were not switched successfully. The reason for this is the running costs and
investment in processors and databases in the network. This measure could
be justified at least for outgoing calls, where UPT calls have to be checked for
approval.
15.4.2 Example of Registration of a UPT Subscriber
Figure 15.8 presents an example of what a communication between UPT sub-
scriber and UPT service provider could look like with a dialogue control over
the telephone.
This UPT function can also be carried out over analogue connections for
terminals, e.g., using DTMF signalling.
First the user dials the access code, which can be in the form of a previously
unused dialling code (in the example #0185). After he has authenticated him-
self by entering his own UPT number and his personal identification number,
he dials the menu for registration. He then requests registration for incoming
calls. Now he can notify the UPT service to which terminal the calls should
be directed and for how long. This completes the access procedure to the
UPT service.
In man–machine communication, especially acoustic communication, it is
particularly important to allow a person a chance to return to the previously
- 784 15 UPT—Universal Personal Telecommunication
Access procedure to UPT service
0185 (Access code for UPT service)
Welcome to your UPT service provider
Please enter your UPT number followed by #:
24569039#
Please enter your PIN followed by #:
____#
You are currently still registered to receive InCalls during
the next 2 hours for terminal 0241880099
Main menu
Please select an entry from the following list:
To finish UPT access please enter *
To register please enter 1
To change your service profile please enter 2
For an outgoing call please enter 3
To redirect calls from another terminal please enter 4
For Outcall-follow-on please enter 5
For operator assistance please enter 6
To repeat the menu please enter #
1
Registrations
You want to register,
please select an item from the following list:
To finish UPT access please enter *
For InCall please enter 1
For OutCall please enter 2
For AllCall please enter 3
For Linked please enter 4
To return to main menu please enter 0
To repeat the menu please enter #
1
InCall Registration
Please enter the local terminal identification number for InCall registration
followed by #:
0241909090#
Please enter the time span during which the InCall registration is valid
at calling identification number 0241909090:
0200#
You have successfully registered for InCall under number 0241909090
for the next 2 hours.
Do you want:
To finish UPT access please enter *
To cancel the InCall registration please enter 1
To return to the main menu please enter 0
*
Thank you for using the UPT service.
Goodbye.
Figure 15.8: Example of an in-call registration with a UPT service provider
- 15.5 UPT Service Profile 785
processed dialogue levels to enable errors to be corrected. In addition, the
user should be able to have personal contact with an operator if assistance is
needed.
15.4.3 Options for Authentication
For security reasons a UPT user must be authenticated before UPT resources
are accessed. This can be done in different ways.
• The easiest way, which requires no intervention in terminals or the net-
work, is authentication using a DTMF transmitter or by dialling certain
numbers at a terminal. These signals are picked up by an appropriate
functional unit and forwarded for evaluation. This type of authentica-
tion is regarded as weak, because it does not provide any special security.
However, this approach can be implemented in every network and at ev-
ery terminal, which is also a requirement of the ITU-T [21]. With this
model the authentication data travels over the traffic channel, which has
already been switched and puts no strain on the signalling network.
• A variation of the above option involves using an intelligent terminal
for an automatic execution of the authentication. The terminal is then
responsible for transmitting the DTMF signals. This option does not
require signalling functions either.
• Card readers and smart cards offer a higher level of security and are
easier to use. As soon as authentication is required, the card-reading
device reads the inserted smart card and carries out the authentication.
The signalling can be implemented over traffic channels or over signalling
channels.
Thus different versions/variations, which are also able to offer different
levels of user comfort, are possible, depending on the terminal intelligence or
authentication security required.
15.5 UPT Service Profile
One of the elements that determines the functionality of UPT is the Flexible
Service Profile (FSP). This is part of a database, and is used to supply the data
associated with UPT users to the Service Control Functions (SCFs). One of
the most important entries in the service profile is the terminal identification
that a user has registered for incoming calls for a specific period of time. With
each call, irrespective of whether it is an incoming or an outgoing call, the FSP
must be interrograted for certain data relating to the call. A differentiation
is made between permanent and variable entries in the structure of the FSP.
Permanent entries relate to data that is fixed when the UPT identification is
- 786 15 UPT—Universal Personal Telecommunication
established and seldom needs to be changed. Variable entries concern data
with values that change owing to actions of the user, such as change of location.
Permanent entries that can be changed only by the service provider include:
• UPT number
• Identification of the home local terminal connection
• Basic services contracted by the subscriber
• Supplementary services contracted
• Number of maximum possible authentication attempts
• Type of authentication procedures
• Security options
• Barred destination numbers (e.g., police, speaking clock)
Permanent entries that can be changed by the subscriber include:
• Approved payment options (e.g.,credit card calls)
• Maximum ceiling on calls
• Maximum number of accesses from other terminals
• Released user functions
The following variable entries relate to service control:
• Type of active authentication
• Active option for charging
• Active security mode
• Status of supplementary services
The following variable entries are used for mobility control and supervision:
• Relevant terminal number
• Fallback terminal for incoming calls
• Relevant terminal for incoming calls
• Standard number of outgoing calls per registration
• Destination for call forwarding—absolute
• Destination for call forwarding—when terminal is busy
• Destination for call forwarding—when there is no answer
• Destination for call forwarding—if called party cannot be reached
- 15.6 Requests to UPT-Supported Networks 787
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Figure 15.9: Functional grouping of UPT
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15.6 Requests to UPT-Supported Networks
A model for the functional architecture of UPT was developed in I.373 [14]
to enable the formulation of requests to the UPT-supporting network. Fig-
ure 15.9 illustrates this model, which consists of five layers hierarchically po-
sitioned underneath each other, which will later be related to the network.
This abstraction is desirable to avoid the need of having to specifiy any spe-
cific form of network. UPT can thus be implemented in fixed as well as in
mobile networks.
A UPT call can cross different networks on its route from the person plac-
ing the call to the person receiving the call. These networks have different
capabilities for supporting UPT. Connections for traffic channels and for sig-
nalling exist between the different network components such as the network
and service profiles. I.373 provides a reference model for UPT calls to present
an overview of the dependences between the individual components (see Fig-
ure 15.10). For each UPT call a different sequence of communication between
- 788 15 UPT—Universal Personal Telecommunication
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Figure 15.11: Example of a UPT call: call between two UPT users
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Figure 15.12: Interfaces in a heterogeneous network configuration
the network components and the service profile is conceivable. Only an ex-
ample of a call between two UPT users is shown here (see Figure 15.11).
When UPT is offered in heterogeneous network configurations, conflicts
can occur because networks have different capabilities for supporting UPT.
Figure 15.12 shows where interfaces occur between networks supporting
UPT and non-supporting UPT. Two possibilities for handling UPT connec-
tions across network boundaries are to be considered. For networks that do
not support UPT, either no UPT service or only a limited UPT service can
be offered.
The same options apply to UPT connections that are to be routed over
non-UPT-supporting networks. The first option is very unsatisfactory, which
is why the second option should be taken into consideration even if additional
costs are involved.
15.7 PSCS as a Further Development of UPT
Personal Services Communication Space (PSCS) is a service concept that was
developed within the framework of the EU research programme RACE by the
Mobilise project partners [5]. PSCS represents a further development of UPT
phase 1, and is serving as the basis for projecting the services and functions
of UPT phases 2 and 3. It enhances the UPT service in the following ways:
- 15.8 Numbering and Dialling 789
• User-friendliness during access
• Use of services beyond telephony, such as fax, e-mail and data services
• Easier access procedures to the service profile
• Flexible routing schemes, such as e-mail forwarding to a fax device
To achieve a certain level of user-friendliness, PSCS requires special termi-
nals that have at least an alphanumeric display and a card reader for smart
cards. Consequently, demands that UPT allow access from any terminal can-
not be met, but what is gained is a far more flexible man–machine interface.
15.8 Numbering and Dialling
In telecommunications networks users are addressed by sequences of digits.
By entering the telephone number of the party being called (user B), the
calling party (user A) is instructing the network to set up a connection. For
technical reasons, direct dialling was previously used to route a call across
the network elements. On the basis of how it is structured, the telephone
number can provide a direct indication of where user B is located with a
direct dialling system. A telephone number therefore has a direct relationship
to the location of user B, and also determines how a call is routed through
the network. Because of the individual numbers that make up the telephone
number, the switching centre is able to route the call to user B.
In addition to addressing users, the telephone number is used for the billing
of telecommunications services. This gives the telephone number economic
significance along with its technical importance.
This direct control has now been replaced by indirect dialling systems,
which is why it is necessary to establish an association between telephone
number and location of user B. In an indirect dialling system the routing of a
call is largely separate from the telephone number. A path established from
the routing tables filed in the switching centres is switched between the two
users. In this case the telephone number only serves for the addressing, and
does not contain any information about a subscriber’s location.
However, users of telecommunications services have the knowledge to de-
termine from the telephone number the calling area of user B, the charges
and type of telecommunications services required. It is therefore important to
retain this information function for the acceptance of new numbering systems.
Current and future numbering systems are explained in the following sec-
tions.
15.8.1 ISDN, PSTN
Telephone numbers in public telecommunications networks as well as in ISDN
for a long time period consisted of 12 digits. Since the end of 1996, this
- 790 15 UPT—Universal Personal Telecommunication
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Figure 15.13: Structure of an ISDN telephone number
number has been extended to 15 digits [10]. The telephone number structure
is provided in ITU Recommendation E.163 [7]; see Figure 15.13.
The country code for Germany is 49. In their structure, national destina-
tion codes indicate the direct dialling control of the network that existed until
about 1977. Like the network, they are arranged hierarchically, with
• position 1 for the central switching centre
• position 2 for the home location switching centre
• position 3 for the customer switching centre
• position 4 for the subscriber switching centre
The national destination code is different for each local network, and typi-
cally unique for a whole country. It consists of two to four digits, depending
on the size of the local network.
A user within the same local network can be reached through his respective
telephone number. Parties in Germany beyond one’s own local network can
be reached through dialling the prefix 0 followed by the national destination
code and the respective telephone number. Users outside Germany can be
reached through dialling the international prefix 00, the country code and
the respective telephone number. The length of the telephone number to be
dialled therefore depends on the distance between the two communicating
parties.
Special services can be selected by dialling special prefixes before the actual
telephone number of the person being called. A 1 is reserved as the first digit
for this purpose. For example, the GSM networks in Germany are accessed
from the fixed network through dialling a 17x.
Telecommunications connections are charged based on the national des-
tination code. Knowledge of the structure of the national destination codes
provides the user with an information source for determining the cost of a call.
According to newer tariffing models there will be probably only two national
tarif zones in the future: local and long distance. Then there will be no more
advantage for the user to differentiate from the destination code where the
long-distance call party is located, and the acceptance of the indirect dialling
system will grow.
- 15.8 Numbering and Dialling 791
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Figure 15.14: Numbering structure in GSM
15.8.2 Public Mobile Telephone Network—GSM
The numbering used in the public mobile telephone network is similar to that
of PSTN. ITU Recs. E.212 [8] and E.213 [9] provide the relevant structures.
The GSM numbering scheme is based on these recommendations.
Figure 15.14 shows how a public mobile telephone number is structured.
It consists of the respective country code, the network code and the terminal
identification number. A complete integration into the ISDN/PSTN num-
bering plan could have been possible, but was not implemented. Instead, as
mentioned above, GSM networks are differentiated from the PSTN through
separate dialling codes which function as a traffic discrimination feature.
15.8.3 UPT
The ITU presents proposals for UPT numbering in Rec. E.168 [13]. In these
proposals a UPT number is defined as a user’s unique identification, and is
dialled by a caller to reach the user. The UPT indicator is the part of the
UPT number that identifies the call as a UPT call, e.g., in Germany 0700 is
used as the prefix.
From the standpoint of the user, the UPT number must meet the following
requirements [12]:
• A UPT number must be recognizable as such by users, so that they have
the opportunity to determine that a call is a UPT call and therefore will
be handled and charged in a special way.
• A UPT number must be as short as possible to minimize the number of
digits to be dialled.
• It must be possible to dial the UPT number from any terminal in the
PSTN. Therefore digits have already been reserved (digits 0. . . 9 and
possibly the characters # and *).
• UPT users should be able to retain their UPT numbers if they change
service provider.
• In the future the UPT number should be valid in all networks, at all
terminals and for the use of any service.
- 792 15 UPT—Universal Personal Telecommunication
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Figure 15.15: Subscriber-based UPT telephone number
• Any further developments and changes to the UPT numbering plan
should have as little an effect as possible on existing UPT numbers.
Network operators have other requirements of UPT numbers:
• It must be easy for a network to recognize a UPT call.
• The numbering capacity must be protected even when UPT is intro-
duced.
• UPT numbers should have no influence on routing.
• The administration of UPT numbers must be kept simple.
• UPT numbers must fit into existing numbering plans (see E.164) [11].
Recommendation E.168 differentiates between three scenarios that all com-
ply with E.164 and therefore are aimed at meeting the requirements of both
user and network operator.
15.8.3.1 Scenario 1—Subscriber-Based Concept
The subscriber-based concept gives no indication to the subscriber that a
call is a UPT call (see Figure 15.15). All information concerning the UPT
subscriber is administered by the Flexible Service Profile (FSP) at his home
location. In scenario 1, CC remains the country code, NDC the national desti-
nation code and SN the subscriber’s telephone number. NDC and SN together
produce a unique telephone number for a country. Owing to the lack of other
criteria, the entire number has to be evaluated and searched in a database to
determine whether the call is to be recognized as a UPT call.
15.8.3.2 Scenario 2—Country-Based Concept
In the country-based concept, CC retains its significance as the country code
(see Figure 15.16). Unlike scenario 1, however, NDC identifies a call as a UPT
call. This applies to the party making the call as well as to the network.
Special codes can be used to select UPT services or a UPT service provider
instead of the local network. This concept has already be applied in the
integration of GSM mobile radio networks. For example, the first NDC digit
can select the UPT service while the other digits would be responsible for the
selection of the UPT service provider.
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