Philip Kelly
Computer
communications
the early days 1966 – 1986 Part 2
As outlined in the first part of Philip Kelly’s article [1], the
British Post Office (BPO), had decided not to implement a
dedicated circuit-switched data network but to await the
digitalization of the UK’s network to provide circuit switched
services. In the second part, further information is given on
the early development of packet-switched data networks
Experimental packetswitched networks
By 1970, George Allery’s staff within
the BPO’s development department
had begun to prepare specifications
for the design and implementation of
a data network based on the packet
mode of working. Much of the details
relating to actual protocols were developed by Mike Smith and his team
[2, 3]. Around the same time, starts
had been made on other experimental
54 | Volume 5 Part 1 • 2011
that enabled the International Telegraph and Telephone
Consultative Committee (CCITT) to finalise the X Series of
Recommendations. He also examines the events leading
up to the establishment in the UK of a public data network
based on the packet mode of working. An indication is also
given of developments in the telex and teletex areas.
networks. In France development had
started on their Réseau à Commutation de Paquets (RCP) [4]; in the USA
the Advanced Research Projects Agency Network (ARPAnet) was being
designed [5] and in the UK the NPL,
together with other research institutions, were involved in developing the
European Informatics Network (EIN)
[6]. There were also other experimental networks being developed such as
Xnett in Norway, one in Canada by
Bell Northern Research and one in
Japan by the Nippon Telephone and
Telegraph.
In the early days, there was still
considerable doubt about how a
packet-based data transmission service should be implemented and as
to what charges for its use should apply. Therefore, the board of the BPO
decided that such a service should
only be introduced on the basis of
an experimental national network for
THE JOURNAL OF THE INSTITUTE OF TELECOMMUNICATIONS PROFESSIONALS
joint evaluation by both the BPO and
by users and terminal manufacturers. Approval for the implementation
of a trial network was not given until
1973 and I was appointed to oversee
all aspects of its implementation and
operation. The Experimental Packet
Switched Service (EPSS) was eventually fully opened for service in 1977,
using Ferranti Argus 700E processors
[7] – see Figures 1 and 2. Photo courtesy of Martin Baker
There was close co-operation at
the time with those experts who were
working elsewhere on experimental
networks and there was a considerable interchange of information on the
specification of protocols that needed
to be developed. The link level and
other protocols, which were developed
by Mike Smith and his team, were
implemented in EPSS but they were
extremely complicated and were proving to be difficult and expensive to realise and it is believed this delayed the
opening of the service. The concept of
“virtual calls” and “permanent virtual
circuits” and the idea of combining
packet transmission and a connectionbased service were found to be of
considerable appeal, especially to the
French. The various presentations and
discussions eventually led to the establishment of agreed standards for a
Link Access protocol. This was based
to some extent on work done within
the International Standards Organisation for a balanced High Level Data
Link Procedure (HDLC) and in addition took account of the preference in
the USA for a master/slave protocol.
Figure 1: EPSS equipment
110bit/s or 300bit/s
Character
terminals
Character and
packet terminal
arrangements
as for Manchester
110bit/s or 300bit/s
Glasgow
48kbit/s
links
110bit/s or 300bit/s
Manchester
48kbit/s
links
2400bit/s or 4800bit/s
Packet
terminals
48kbit/s
links
48kbit/s
Character and
packet terminal
arrangements
as for Manchester
Packetswitching
exchange
London
Connections via PSTN
Data
terminal
equipment
Direct connections
Figure 2: EPSS schematic at its opening in 1977
Eventually the CCITT, via its special
rapporteur group for the packet mode
of working, recommended an agreed
Link Access Protocol Balanced (LAPB)
and this was incorporated into Recommendation X.25 and many other data
link protocols for services being implemented during the 1980s.
EPSS was basically a test bed. It was
of particular value in enabling the data
processing industry, users and the BPO
to evaluate the technical problems of
implementing packet switching protocols in computer terminal equipment.
Other countries followed the development of EPSS with considerable interest. From EPSS much was learned
about the concept of layered modelling
of protocol structures, (network, transport, virtual terminal, file transfer etc.)
together with practical experience in
attempting open systems working between different computer systems.
All the time EPSS was being developed, the CCITT continued to refine
its Recommendations for packet-based
services. Enhancements were made to
X.25 and, within the Conference of
European Postal and Telecommunications Administrations (CEPT) drafts
for what eventually became CCITT
Recommendations X.28 and X.29 for
character-based terminals were developed under the chairmanship of John
Wedlake who eventually took over as
Chairman of the CCITT Study Group
VII in 1986 and continued in this post
until 1993.
EPSS was never expected to be
commercially viable as no charges for
its use were to be levied; only dummy
bills would be issued and these were
based on the number of packets transmitted. EPSS was soon overtaken by
the development of international standards for user terminal/packet switching network interfaces. In particular
the issue by the CCITT of the X.25
Recommendation in 1976 had a profound effect on developments as did
advancements in microprocessor technology. EPSS was not compatible with
the Recommendations in the X series
particularly X.25 and it was not considered economical for it to be modified. It was in due course withdrawn
from service.
Charging principles and
tariffs
Even though it was not intended to
charge for the use of EPSS, it was
considered that an early start should
be made on determining the charging structure that should apply to
networks based on the packet mode
of working. Tariffs for telecommunications services needed to be set by the
BPO’s service department that had, at
the time, little or no understanding of
computer communications and were
only really interested in obtaining
the appropriate rate of return on the
actual investment. The tariff division
was headed by Ena Knight who had
graduated with an engineering degree
Volume 5 Part 1 • 2011 | 55
but could not join the BPO’s engineering department which was, at the time
she graduated, a male-only preserve.
She thus joined the BPO’s traffic department dealing with service and
policy matters. Following pressure
brought by the marketing department
and myself, the charging rules for
packet-based services were agreed in
principle and were to be quite different from those for conventional telephony services.
There had already been some discussions on the subject of charges,
initiated by Larry Roberts of Telenet
in the USA, with Dave Horton of Bell
Canada, Philippe Picard of France and
myself. It was proposed by this group
that, in spite of the various geographical sizes of countries, access charges
should be dependent on the access
data signalling rate but independent of
the distance of the terminal from its
packet switching exchange. A charge
should however be levied for the number of packets transmitted. The CCITT
issued in 1977 Recommendation D.10
relating to general tariff principles (Orange Book Vol II.1). These principles
were accepted by Ena Knight for the
UK network and thus call patterns
were monitored on EPSS and nominal bills prepared. The proposal that
charges should be independent of
distance seemed to reflect the postal
universal charge which perhaps was
appropriate for “packets”.
The Eurodata Foundation
Whilst the International Computer
Communications Conferences (ICCCs), to which considerable reference
has been in given in Part 1 of this paper [1], enabled there to be discussions between technical people, there
was little attention to the marketing
or charging aspects for new data services. In 1971, Torsten Larson, the
then Deputy Director of the Swedish
Telecommunications Administration
called a small meeting in Stockholm
at which both Halvor Bothner-By,
the CCITT Special Rapporteur for the
packet mode of working and myself
were present, to consider a proposal
by American consultants to undertake
a market study on data communications in Europe. Following this meeting CEPT Administrations jointly invited international tenders for such a
study and this led to the publication
56 | Volume 5 Part 1 • 2011
of the “Eurodata 1974 Study” [8]. This
study indicated a significant increase
in the number of data terminals over
the next decade and to the need for international interworking but the study
did not take into account the existence
of specialised data networks. In 1976
an Eurodata Foundation was formally
established in London with members
drawn from the CEPT Administrations. Its main role in the early days
was to provide a forum for members
to exchange information on the telecommunications market. In 1979, the
study of tariff information became the
focus of activity, especially the tariffs
for public data networks. In 1981 it issued its 4th edition of a report on the
plans of the Administrations for public
data networks which by then included
tariff information. In 1999, the Foundation became Teligen Ltd and continues to supply information relative to
telecommunications services and the
tariffs which apply.
The National Committee
on ComputER Networks 1976
As often happens in Government or
semi government departments when
things are uncertain, a committee is
set up with loosely defined terms of
reference to consider and report back
in, say, a year or two, by which time
the situation might have resolved
The tariff division
was headed by Ena
Knight who had
graduated with an
engineering degree
but could not join the
BPO’s engineering
department which
was, at the time she
graduated, a male only
preserve. She thus
joined the BPO’s traffic
department dealing
with service and policy
matters.
itself. In 1976 in the UK, the Secretary
of State for Industry, Eric Varley, no
doubt as a result of considerable pressure from scientific institutes, manufacturers and users, decided in true
“Yes Minister” style to set up such a
committee to be known as the National Committee on Computer Networks
(NCCN) to consider the development
of computer networks in the light of
national economic and social factors,
taking into account the joint interest
of users, hardware and software suppliers, standards and the relationship
between private and public networks.
It was headed by Dr. Jack Howlett
from the Atlas Laboratory. Of the fifteen members it is interesting to note
it included Donald Davies, and my
successor as the head of the Civil Service Department’s computer division
Ray Atkinson, Frank Thomas the then
director of BPO’s network planning
department, and industry representatives such as Peter Hermon from British Airways. Bryan Stanley from the
Post Office Engineering Union was
also appointed. On occasions I deputised for Frank Thomas and provided
him with detailed technical and commercial support.
Surprisingly NCCN produced a report within two years [9] concluding
and recommending amongst other
things:
• The need for a public switched data
transmission service with international connections was seen as important and urgent.
• A service using packet switching
should be introduced as the first
step.
• The service should be provided by
the BPO as part of the national telecommunications services and the
tariffs should be distance-independent within the UK and pitched at
an attractive level.
• The BPO’s plans recently announced
for a Packet Switched Service (PSS)
were welcomed but it was noted
there was no firm commitment and
the planned rate of growth was considered to be on the low side.
• The Department of Industry should
consider contributing towards the
cost and should also consider underwriting any start-up losses.
• The BPO should improve its customer relations and give increasing
advice regarding the problems of
THE JOURNAL OF THE INSTITUTE OF TELECOMMUNICATIONS PROFESSIONALS
connecting to the new network. Its
monopoly in the provision of modems for connections to the PSTN
should be removed.
• Subscribers should be free to connect any approved equipment to the
Data Communications Equipment
(DCE)/ Data Terminating Equipment (DTE) interface and the procedure for approving attachments
should be simplified.
• The policy regarding interworking
between public and private networks should be modified to encourage inter-communications.
• Message switching as a private
commercial venture should be licensed on a limited basis.
The report was in general accepted
by those involved but reservations
were expressed in the report by Frank
Thomas on behalf of the BPO and by
Bryan Stanley on behalf of the unions.
Towards the end of NCCN’s work, the
BPO had actually announced plans
for a 9-node national PSS in full accordance with the relevant CCITT
Recommendations to supersede EPSS.
Opening was expected to be in 1979.
Frank Thomas felt that the planned
growth for PSS was very flexible and
adaptable to any demand. On the other hand Bryan Stanley on behalf of the
Post Office Engineering Union could
not agree to proposals regarding:• The relaxing of any rules regarding
what could be attached to the network
• The ability of private networks to
be able to interconnect with public
networks
• That the BPO’s interest should end
at the DCE/DTE interface.
NCCN’s report more or less laid
out a firm plan for the provision of a
national packet-switched data service
and it was interesting to note the acknowledgement it effectively gave to
the small group of people in the BPO
whose efforts to provide new services
were often frustrated at every stage of
implementation.
As is mentioned later PSS did not
in fact open in 1979 as announced but
in 1981, mainly due to contractual and
implementation problems.
The Euronet/DIANE project
The Commission of the European
Communities (CEC) had set up a Directorate General XIII within which a
Copenhagen
Dublin
Amsterdam
London
Frankfurt
Brussels
Luxemburg
Paris
Packet switching exchange
Remote access facility
Network management centre
Rome
9600bit/s link
48kbit/s link
Figure 3: Euronet at its opening in 1978
department under Dr Georges Anderla
was to consider the need for making
information readily available throughout the then existing Community. An
international information network,
based to some extent on the concepts used in the networks set up by
the Airlines (Society International for
Telecommunications Aeronautic) and
by the Banks (Society for Worldwide
Interbank Financial Telecommunications) was proposed. Telecommunications Administrations felt this was
too big a concept and urgent meetings were held with the Commission
at which it was agreed that the actual
communications network would be
provided by the Administrations and
that the Commission would take responsibility for the information to be
transmitted over the network. Thus
the concept of Euronet, and the CECsponsored database access service
which would use Euronet, was born.
This latter service - Direct Information
Access Network, Europe - was given
the acronym DIANE, thus clearly
showing the split between communications and the information accessible
over Euronet [10,11].
As vice chairman of the CEPT’s data
communications group, I took on the
part-time task of overseeing the implementation of the network. In 1976 I
was promoted to become the deputy
director in charge of the planning of
the trunk network other than the transmission elements and thus gave up my
national responsibilities for data transmission. However it was agreed that
I could continue my oversight of the
Euronet project because of its significant implications for the future of international data transmission. A small
project team under the leadership of
Jean-Yves Gresser from the French Administration was established in Paris
with seconded members from various other European Administrations.
A member from the BPO joined this
team and another took a post with the
Commission. Following the issue of
tenders, a network was implemented
utilising the same technology as was
used in the French Transpac system.
Although not without its difficulties,
it was successfully implemented and
opened for service at the end of 1978
– see Figure 3.
A network management centre was
established in London. Traffic was
quite low at the beginning because of
Volume 5 Part 1 • 2011 | 57
the problems of interfacing the many
hosts which were to provide the information content, a common problem
that occurred every time a suitable
specialised network was established.
However, soon after its completion,
it became obvious that the individual
European Administrations were then
actively implementing their own national networks and interconnecting
them using X.75 links. Euronet was
then in effect redundant as its traffic
could be carried by these interconnected national networks. It was a
difficult task for the CEPT to convince
the CEC that Euronet should be closed
down because it had been a success in
that it had forced Administrations into
providing their own packet-based networks even in those countries that had
mainly gone down the circuit-switched
path. Euronet was eventually closed
down at the very end of 1984 [12].
Digitalisation of the
trunk network
As mentioned earlier, in 1976, I was
promoted to deputy director and I
moved to take charge of the planning
and implementation within the trunk
(long distance) network of an Integrated Digital Network (IDN). Perhaps
it was significant that at the same time
the CCITT special rapporteur for the
packet mode of operation was also
transferred to work on the proposed
IDN in Norway. I recruited Keith Ward
to assist me in my new role but, as
mentioned, managed to retain my part
time international responsibilities for
Euronet. Studies had been completed
into the feasibility of introducing digital switching and transmission into
the UK trunk network in 1974 [13].
However the study was orientated towards integration of existing analogue
switches, both Strowger and crossbar,
as used in the transit network and the
host of complicated signalling systems
involved. After a quick analysis of the
current situation it was decided that
much of the feasibility report should
be disregarded and that a start should
be made almost from scratch on an
overlaid digital switched network.
Economic studies clearly showed that
implementation was needed on a
joint transmission and switching basis. Frank Thomas, as the then director of network planning department,
endorsed this approach and, together
58 | Volume 5 Part 1 • 2011
Datapac
Teleglobe
Infoswitch
Norway
Sweden
Norpac
Swenet
Canada
Switzerland
KDD
Japan
International
data centre
London
Telenet
Tymnet
USA
ITT
RCA
WUI
NTT
DS 50
International
gateway
Euronet
Ireland
Hong Kong and
Singapore
PSS
UK national
network
Australia via
OTC gateway
France
FRG
Italy
Denmark
Netherlands
Belgium
Luxemburg
Ireland
UK
Node transit
international
Transpac
RETD
Spain
Existing
Planned
Figure 4: IPSS in 1978
with Geoff Simpson who headed the
transmission divisions, the digital network began to take place. The key
was that once a digital trunk exchange
that switched 64kbit/s circuits was deployed, all transmission links to that
exchange would be via digital systems
with analogue to digital conversion occurring at the remote connected analogue exchange. Once further digital
trunk exchanges were introduced, the
links between digital exchanges would
be fully digital and the analogue to
digital conversion equipment would be
moved to new locations. The first digital trunk exchange was opened in 1983
and by 1987 the trunk network in the
UK had become virtually fully digital.
My period planning for the digital
trunk network was very rewarding
because it was clear that digitalisation
was feasible and necessary and thus
there were little or no financial problems with actual implementation. It
was also clear that, once an IDN had
been established, the addition of local digital exchanges enabled the possibility of establishing an Integrated
Services Digital Network which could
provide the basis for a circuit-switched
data service, the introduction of which
(mentioned in Part 1 of this paper [1])
had been postponed in 1974. However following a major reorganisation
in 1979 the network planning department as such disappeared and I became the deputy director (non-voice)
located within the System X-orientated
exchange systems department headed
by John Tippler. My responsibilities
covered not only data networks but
telex and Datel services as well.
The International Packet
Switched Service (IPSS)
The need for character terminal database access services to be extended
internationally was recognised quite
early and an international database
access service to Tymnet via the three
International Record Carriers in the
USA was opened by the BPO using
proprietary equipment and protocols
in 1977. It quickly demonstrated the
demand for international services. Following the definition of EPSS, public
packet-switched networks had begun
to be established in the USA, Canada,
Spain, France and Japan, again based
on national protocols. The new CCITT
Recommendations were rapidly being
adopted in these countries. Because
of considerable international interest
in data communications, the external telecommunications executive of
the BPO (by then split into separate
postal and telecommunications parts,
the latter, later becoming British Telecommunications (BT)) decided that
an international packet-based service
was essential and IPSS was opened in
1978 [14] (Figure 4) with connections
to the three USA International Record
Carriers using Telenet TP4000 packet
switches to CCITT Recommendation
X.75 ratified in 1978. Connection to
other countries followed also using
X.75. As interconnection to EPSS was
not technically feasible, access was via
leased lines for terminals conforming
to X.25 or via dial-up connections for
terminals conforming to X.28. It was
understood that once the BPO had introduced an inland X.25-compatible
network, access would be via that
THE JOURNAL OF THE INSTITUTE OF TELECOMMUNICATIONS PROFESSIONALS
Opening date
Glasgow
Installed but not
in operation at
opening date
Edinburgh
1981 extension
Newcastle
Figure 5: PSS equipment
network. However, for various reasons
that did not happen until 1981. Once
opened, customers were transferred
from the IPSS international gateways
to the national nodes and the number and speed of international links
were increased. Similarly the Euronet
packet switches and network management centre, which were co-located
with the IPSS packet switches, were
subsumed into national/international
services when Euronet closed in 1984.
The international packet switching
gateways, originally Telenet TP4000,
were replaced by Alcatel Bell systems
in 1986.
With the IPSS, again charging issues arose and it was decided that IPSS
would provide a virtual call packet service. This was a service option which
ensured all packets followed the same
path and it provided an easier way to
implement the international accounting agreements between Administrations and/or Recognised Private Operating Agencies which historically had
been introduced as a revenue sharing
system for all international telecommunications services.
The public PSS
In 1976 I had been transferred to other
duties and Brian Cross took over my
UK responsibilities for data systems
planning and had the daunting task of
preparing the necessary papers seeking
board approval for PSS. It had already
become obvious that modifying the
EPSS network to meet the new CCITT
Recommendations was not a satisfactory solution and specifications for
PSS were thus drawn up and finalised.
Board approval was given in 1978 for
its implementation. Eventually a contract was placed in 1979 with Plessey
Controls (Poole) who had obtained a
licence to utilise the Telenet TP 4000
Manchester
Leeds
Liverpool
Birmingham
Bristol
Cambridge
London
Slough
Reading
IPSS
NMC
Figure 6: PSS at its opening in 1980 with the 1981 planned expansion
packet switches. PSS was duly implemented and opened for service in the
early part of 1980 [15] – see Figures
5 and 6. Access was by directly connected leased lines or dial-up via the
PSTN, in both cases using modems
from the Datel range. At a later stage,
once digitally-based facilities such as
BT’s KiloStream became available in
1984, these were also used for direct
access links to the packet switching exchanges, better now known as
nodes. PSS was of course connected to
IPSS from the outset. Photo courtesy
of Martin Baker.
Elsewhere public data networks
based on the packet mode of working
began to make their appearance. One
of the first was the “Red Especial de
Transmisión de Datos” (RETD) [16]
which was operational in Spain in
1971 offering terminal-to-host facilities
as well as message switching. Telenet
in the USA opened in 1975, Datapac in
Canada in 1977, Transpac opened in
France in 1978, Euronet in 1978 and
others followed but PSS in the UK did
not open until 1980.
Early users of PSS were however the
UK Banks. They had set up a Clearing
Houses Automatic Payment System
(CHAPS). At a given time each day
they interchanged monies between
themselves. To meet this requirement
they were provided with a closed user
group facility within PSS. However, to
avoid problems with investors and the
Stock Exchange if traffic flows were to
become known in the public domain,
dummy packets were transmitted at
other times of the day. Thus a private
switched network was established
within a public network to the satisfaction of everyone.
With the ordinary
charging structure the
amount of information
recorded for a given
transmission could far
exceed the amount of
data transmitted
Volume 5 Part 1 • 2011 | 59
Telex and teletex
Within the development department,
at the same time as PSS was being
developed, detailed specifications
were being drafted for replacement
digital telex exchanges to incorporate
message switching as well as a teletex service, (not to be confused with
the non-interactive broadcast teletext
services associated with television
transmissions). The teletex service
had been fully defined by the CCITT
SG I in June 1980 as an upgraded telex service which operated at 300bit/s.
The service was strongly advocated
by the Federal Republic of Germany,
no doubt fully supported by their
main contractor Siemens [17]. In the
UK it was decided to go ahead with
tenders for the supply of new stored
program control telex exchanges
with add-on options for a teletex
and message switching service. A
contract was eventually placed via
GEC with their subsidiary Canadian
Marconi Company [18] who in turn
sub-contracted the necessary software to a Canadian firm who in turn
subcontracted some software development to Norway. Hardware manufacture and installation proceeded on
schedule but there were considerable
delays with the software. Plessey
Controls (Poole) were however given
a separate contract to supply an exchange in Fleet in London complete
References
1. Kelly, P.T.F. Computer
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days 1966 – 1986 Part 1.
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of Telecommunications
Professionals, Vol. 4 Pt. 4,
December 2010
2. Belton, R.C. and Smith, M.A.
An Introduction to the British
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p216, January 1974
3. Spooner, M.J., Wilson, E.J.,
and Neil, W. Experimental
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1 and 2. Post Office Electrical
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p232, January 1975 and Vol.
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4. Després, R. RCP, The
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Computer Communications
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6. Barber, D.L.A. The European
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7. Hadley, D. and Medcraft,
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1973-1985. PA Management
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9. The report of the National
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Kelly, P.T.F. and Thomas,
J.R. The EURONET
Telecommunications and
Information Network.
Proceedings of the 4th
International Conference on
Computer Communications,
Kyoto 1978, p189
11.Kelly, P.T.F. The Euronet
Telecommunications and
Information Network. Institute
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November 1979
12.Broomfield, C.F. International
Packet Switching Trends.
Proceedings of the European
Computer Communications
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13.Breary, D. A long term Study
of the United Kingdom Trunk
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14.Ford, M.L. And Davies, F.W.
International Data Networks UK Post Office Experience and
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15.Medcraft, D.W.F. PSS - The
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Data Service. International
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81 pp 4-1 to 4-11
16.Alarcia, G. and Herrera.S.
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Proceedings of the 2nd
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17.Rüggeberg, R. The Development
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Proceedings of the 6th
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London 1982, p338
18.Daniels, E.E. Telex Switching
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19.Altehage, G. and Staudinger,
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THE JOURNAL OF THE INSTITUTE OF TELECOMMUNICATIONS PROFESSIONALS
with a message switching element.
Eventually the software problems in
Canada were overcome, the detailed
specifications having been relaxed to
some extent, and the modernisation
of the telex network went ahead and
was completed in 1986. New generation telex machines were also introduced. The Fleet exchange never
became operational and was in due
course replaced by Canadian Marconi Company exchanges towards
the end of the 1980s. The ad hoc options, namely teletex and message
switching were never in fact introduced in the UK, probably due to the
comments made in the NCCN report
and in due course the availability of
e-mail utilising the Internet.
A teletex service was however introduced in some European countries,
mainly those such as the Federal Republic of Germany, the Nordic group
of countries and Austria who at that
time saw teletex as part of a range of
circuit-switched services [19]. The telex service was extremely popular and
profitable during the 1980s. BT offered
a prize to the person who became the
100,000th user of the service. But like
some other services such as the Datel
services it then went into decline and
in the UK no further investment in the
service was made. Modernisation of
the telex network was in fact the last
attempt to develop low speed circuitswitched data services in the UK but
such services did not materialise.
AUTHOR CONCLUSIONS
Following experience with experimental networks like EPSS and with the
finalisation of the X series of Recommendations, by the early 1980s X.25based packet-switched networks were extensively deployed and offered
service worldwide. Not least of the battles that had been overcome were
the charging principles and tariffs given the very different nature of the
traffic compared to telephony. However, 64kbit/s circuit switching technologies leading to ISDNs and new high-speed digital transmission facilities leading to the Internet were emerging and saw the gradual demise of
X.25-based packet networks. This stage of the story is addressed in Part
3 of this paper appearing in the next issue of The Journal.
Acknowledgements
I would specially like to thank Chris Broomfield for his contribution on
International Services and also to all those who were associated with the
introduction in the UK of the public data networks for their dedicated
assistance and pursuit of objectives against often considerable objections
and opposition. They should all be pleased with the outcome and the part
they played at various times in its implementation.
Abbreviations
BPO
BT
CCITT
CEC
CEPT
British Post Office
British Telecommunications
International Consultative Committee for Telegraphs and Telephones
Commission of the European Communities
Conference of European Postal and Telecommunications
Administrations
DCE
Data Communications Equipment
DTE
Data Terminating Equipment
EPSS Experimental Packet-Switched Service
ICCC International Computer Communications Conference
IDN
Integrated Digital Network
IPSS
International Packet-Switched Service
NCCN National Committee on Computer Networks
PSS
Packet-Switched Service
Phillip Kelly
About the author
Phillip Kelly joined the GPO Engineering Department as a youth-in-training in 1944. He studied part time at various technical colleges, eventually graduating with an Engineering Honours
degree in 1950. He then joined the Lines Branch of the Engineer in Chiefs Office. In early
1953, he was assigned as a systems engineer, to the Project Team set up to implement the first
Transatlantic Telephone Cable System. Following the completion of the TAT1 Cable System, he
moved to cover the planning and implementation of several European Cable systems including
the Anglo-Swedish one. He then returned to the Oceanic Group to work on TAT 3.
Awarded a Nuffield Travelling Fellowship in 1964, he had a year’s sabbatical study in Sweden
and Canada. Returning to the UK he became involved with the design and implementation of
computer systems for repetitive engineering tasks. He moved on secondment to HM Treasury in 1967 as head
of the Governments Computer Division. When the Post Office was made a Public Corporation in late 1969,
he returned to become head of the newly formed Data Systems Division where he was involved in complex
studies and decisions regarding the use of packet or circuit switched systems for data transmission. He next
became a Deputy Director of Network Planning overseeing the first plans for digital switching in the Trunk
Network and then Deputy Director for non-voice networks. His final appointment was as Chief Engineer of
Specialised Networks. In 1983 he retired on health grounds but soon afterwards became a consultant to BT
Telconsult, and to manufacturers and IT companies. Later he took on the post of the first Executive Director of
the European Electronic Mail Association a position which kept him involved until the late 1990s. He became
a Freeman of the City of London in 1960.
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