TELECOMMUNICATIONS
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INTERCONNECTION AND
INTEROPERABILITY
A framework for competing networks
April 1997

As telecommunication markets get ever more competitive, new and innovative
services are becoming available from both network operators and independent service
providers.
Consumers will want to be able to use new services whether or not they are
customers of the operator which has launched the service, and whatever customer premises
equipment they use, and operators will want their services to be available as widely as
possible. For this to be possible, services will need to be interoperable across competing
networks.
This Statement is about how interoperability should be organised, both at
customer interfaces between networks and customer premises equipment and at
the network interfaces at which network operators interconnect their systems. It follows
on from previous consultation on customer interfaces, and extensive industry debate on
network interfaces and interconnection.
I would welcome your views on our conclusions.
Based on an Article by: DON CRUICKSHANK

INTRODUCTION
1.1 OFTELs objective is to provide the best possible deal for
customers in terms of quality, choice and value for money, and it believes that this
objective can best be met through a fully competitive market competition provides choice, drives down prices, and spurs innovation.
The regulatory framework must therefore, seek to promote competition both in the provision
of services and between alternative networks. Competition at the network level ensures
competitive supply of the network services which are inputs to retail services and
consequently deepens competition at the service level. It also leads to a market where
competition is the driving force at all levels and where regulation
can therefore pull back as competition takes over.
1.2 Interoperability of services between the networks of different operators,
and between networks and the equipment used by customers to access them, is essential to
consumers who need to be able to make calls to other consumers irrespective of whether
they are directly connected to the same network. In a monopoly network, interoperability
is straightforward because interworking of the network and equipment attached to it
is an internal matter for that organisation, and central to its business. However, where
there are competing networks supplied by competing switch manufacturers and there is
competition in the supply of customer premises equipment, interoperability is not so
easily assured.
1.3 If networks are fully competitive, one would still expect there to be strong
incentives for operators to organise interoperability to their mutual commercial benefit
because each network will want to ensure that its services are available to as many
customers as possible. However, where one network operator has market power, there may be
difficulties because it may be commercially attractive to such an operator to make some
services available only to its own customers. Where these are services which could be made
available to customers on other networks, competition problems can arise.
1.4 This Statement is about how interoperability should be organised in the
competitive framework of telecommunication markets. It presents OFTELs conclusions
on the following two strands of work:
 | Consultation on Customer Interfaces contained in the consultative document, The Customer Interface to Public Networks,
published in July 1995.
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 | Extensive industry discussion on interoperability and interconnection of services
at the network level, both at the Interconnect Policy Forum (IPF) and in its Focus Group
which considered the interconnection of new services. |
1.5 It identifies those services for which we believe it will be necessary for
there to be rules to promote interoperability, and presents conclusions on what those
rules should be and how they should work in practice. Consistent with the belief that
customers are best served by effective competition, we must seek to propose regulation
only where it continues to be needed and will, wherever possible, seek to operate through
guidelines rather than detailed licence conditions.
1.6 The Statement necessarily contains discussion of some quite complex economic
concepts and technical terminology.
For reference, definitions of key terms are provided at Table 1.1, and a full
glossary is at Annex G.
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Table 1.1 Definitions of Key Terms
| What is OFTEL? |
| The
Office of Telecommunications (OFTEL) is the regulator for the UK telecommunications
industry. OFTEL was set up
under the UK Telecommunications Act 1984.
Their goal is to make sure the
public receive the best quality, choice and value for money for all their telephone
services. |
| Interconnection |
| Interconnection means the
physical and logical connection of two operators networks thereby allowing customers
of one system to connect with customers of the other, or to access services provided from
the other system. |
| Interoperability |
| Interoperability means the
technical features of a group of interconnected systems (systems includes
equipment owned and operated by the customer which is attached to the public
telecommunication network) which ensure end-to-end provision of a given service in a
consistent and predictable way. Interoperability is defined here in terms of the
functional delivery of services across networks it does not necessarily imply that
component parts of the systems over which such services are delivered are interchangeable.
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| Network Interface |
| Where two operators
networks are interconnected, each must be able to understand the technical operation of
the other in order for services to interoperate across the interconnection boundary. The
technical characteristics that allow for that understanding is the Network Interface. Each
network must provide an interface at the point of connection and only where these
interfaces are compatible will there be Interoperability. |
| Customer Interface |
| Where a public
telecommunications network is connected to a customers network or apparatus (at the
Network Terminating Point) the network and the customers system must each be able to
understand the technical operation of the other in order for services to interoperate
across the connection boundary. The customers system and the network must both
provide an interface at the point of connection and only where these interfaces are
matched will there be Interoperability. The technical characteristics that allow for that
understanding is the Customer Interface. |
| Network Services |
| Network Services are
services that can only be technically and economically provided by those who build their
own telecommunications network infrastructure. BT Network Services (including the elements
of these services which are necessarily incidental to the provision of them, like billing
customers for the provision of the service) are provided from its Systems Business,
Enhanced Services are provided from the Supplemental Services Business. It should be
recognised that, notwithstanding the juxtaposition with Enhanced Services, Network Service
does not necessarily mean simple, or plain old telephone services
(POTS). Network Services may be extremely complex and/or new developments. |
| Enhanced Services |
| Services that can be
economically provided by independent service providers (ie those who do not build their
own telecommunication network infrastructure) in competition with network providers as
long as they can gain access to Network Services. The regulation of BT ensures that this
is the case in respect of access to BTs Network Services. Examples of Enhanced
Service are the provision of content for premium rate services and the provision of retail
Internet services. |
| Co-operative Service |
| A Co-operative Service is
a service which requires a specific capability between networks in both the originating
and terminating networks, both within the networks and at the point of interconnect.
Examples of Co-operative Services are normal telephony, premium rate services, Ring Back
When Free, and CLI display services. |
| Non Co-operative Service |
| A non Co-operative Service
is a service that requires a specific capability only on the network to which the customer
using the service is connected (eg at the local switch) and/or the services economic
viability is not dependent on the total number of switches and/or network termination
points enabled to originate or receive such a service. Examples of such services are call
waiting, call minder, three way calling, (simple) call diversion and the speaking clock. |
Which services need rules to ensure
interoperability?
1.7 A key part of the analysis of interoperability has
been identifying the circumstances in which it is appropriate for there to be rules
governing interoperability.
Market power
1.8 OFTELs analysis of interoperability has
concluded that whether or not rules should apply in different circumstances depends
crucially on the market power of the operator. In considering the interoperability of
services, OFTEL has concluded that market power results directly from the control of
access to addressable customers (ie consumers to whom calls can be made). An
operator to whose network a large proportion of customers are directly connected therefore
has market power in this context because a small operator will need to interconnect with
it if the small operators customers are to be able to make calls to the large
operators customers. The same is of course true for a customer of the large operator
wishing to call a customer of the small operator, but there is a clear asymmetry in the
position because the large operator controls lines to a larger number of customers and
lack of interoperability is hence a bigger problem for the small operator than it is for
the large operator. The purchasing power of the large operator and its consequent
influence on interface standards will also enable it to leverage its market power in the
markets for supply of equipment for use in networks and customer premises equipment.
1.9 Where markets are competitive, there will be no need
for any regulatory intervention to promote interoperability because there will be a strong
commercial incentive for operators to organise interoperability between themselves for
services which require it.
Interoperability and innovation
1.10 Another important consideration
in identifying those services for which it is appropriate for there to be rules on
interoperability is the trade-off between interoperability and innovation. In
summary, the issue is that there is potentially a conflict between, on the one hand,
encouraging innovation whereby operators legitimately seek rewards through
differentiation and exclusive provision of their new innovative services and
interoperability which ensures wider distribution of the benefits of new services
through its availability more widely than just on the network which launches them.
1.11 The analysis that the promotion of
interoperability for certain types of service where the market is potentially distorted by
an operators market power will not act as a brake on innovation, and that,
furthermore, this will only involve intervention to promote interoperability of services
for which, in a competitive market, there would in any case be strong incentives for the
industry to organise interoperability itself.
Network and Enhanced Services
1.12 OFTEL has identified those services for which it is
appropriate for there to be regulatory rules to promote interoperability.
1.13 OFTELs Statement, Promoting Competition in Services over
Telecommunication Networks published in February 1997 established the distinction
between Network and Enhanced Services. Network Services are those which can realistically
and economically be supplied only by network operators, and Enhanced Services are those
which can be supplied by independent service providers (ie those not building their own
network infrastructure) as long as they can get access to the Network Services which they
need to deliver the service.
Network Services
1.14 A distinction can be drawn between those Network
Services which, by nature, only need to work within one network for example,
services like Call Waiting and Call Diversion the functionality
for which usually resides in the local exchange and those which need to be
interconnected between networks in order to work on calls between customers on those
networks for example, Ring Back when Free and Calling Line
Identification. The latter are defined in this Statement as Co-operative Network
Services (see definitions).
1.15 Interoperability of Co-operative Network Services is
desirable both for customers, who want to be able to use these services in calls to other
customers irrespective of whether they are directly connected to the same network, and for
the development of competition. Interoperability benefits the development of competition
on two levels. Firstly, between network operators because the unavailability of such
services on small networks could unfairly hinder their ability to compete. And secondly in
markets served by independent service providers because, without interoperability, their
services will not be available to all addressable customers and they will be likely to use
the operator with market power to carry their services (because it will provide access to
the most addressable customers), and hence lose the benefits arising from choice of
carrier. OFTEL has therefore concluded that special rules to promote interoperability
of Co-operative Network Services at network interfaces are necessary.

1.16 All Network Services need to work across customer
interfaces so that customers can access the functionality in the network necessary to use
the service. OFTEL has therefore concluded that rules to promote competitive supply and
interoperability of all Network Services at customer interfaces are necessary.
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