HOME
The Info List - Subscriber Trunk Dialling





Subscriber trunk dialling
Subscriber trunk dialling
(STD, also known as subscriber toll dialling) is a telephone system allowing subscribers to dial trunk calls without operator assistance. The term was introduced when it first became possible for long-distance calls to be dialled directly, and is now rarely used where calls to any destination can be dialled.

Contents

1 Terminology 2 Explanation 3 History

3.1 Numbering plan 3.2 Calls from Ireland

4 See also 5 References 6 External links

Terminology[edit] The term subscriber trunk dialling is used in the United Kingdom, the Republic of Ireland, Australia, India
India
and South East Asia. The corresponding term in the North American Numbering Plan, e.g. in the United States and Canada, is direct distance dialing. The term was extended when, on 8 March 1963, subscribers in London were able to directly dial Paris using international direct dialling. Explanation[edit]

Typical signboards of STD booths (kiosks from where STD calls can be made) in India

The introduction in the UK of subscriber dialling of long distance calls removed the distinction that had existed between trunk and toll calls. This term however, is still widely prevalent in India
India
to describe any national call made outside one's local unit. A "subscriber" is someone who subscribes to, i.e. rents, a telephone line and a "trunk call" is one made over a trunk line, i.e. a telephone line connecting two exchanges a long distance apart. Now that all calls may be dialled direct, the term has fallen into disuse. History[edit] When telephone systems were first introduced, subscribers called a telephone exchange and asked a human operator to connect the call to another subscriber on the same exchange; calls to other exchanges were originally not possible. Later it became possible to dial numbers on the same exchange; calls to other exchanges (trunk calls) were possible, but had to be connected by an operator. When subscribers in one area became able to dial non-local subscribers, the term used for the innovation was subscriber trunk dialling. In the UK, STD started before 5 December 1958 when the Queen, who was in Bristol, publicized it by dialling Edinburgh
Edinburgh
– the farthest distance a call could be directly dialled.[1] The STD system was completed in 1979,[2] though most of the country was covered well before then. The system required that a new STD code, which could be dialled by subscribers, be allocated to each area; in the UK area codes are still sometimes called STD codes. Numbering plan[edit] With the introduction of subscriber trunk dialling each city with a Director system was assigned a 3-digit code, in which the second digit corresponded to the first letter of the city name on the telephone dial, with the exception of London which had the two-digit code 01. Codes were later changed (e.g., London became 020, and Manchester 0161).

01 London 021 Birmingham 031 Edinburgh 041 Glasgow 051 Liverpool 061 Manchester

Calls from Ireland[edit] Until 1992, calls to these cities from Ireland required the following codes:

031 London 032 Birmingham 033 Edinburgh 034 Glasgow 035 Liverpool 036 Manchester

In that year, this changed to dialling in the international format 0044, and the 03 range was withdrawn from use. See also[edit]

Trunk prefix Telephone
Telephone
numbers in the United Kingdom Telephone
Telephone
numbers in India Telephone
Telephone
numbers in Australia Telephone
Telephone
numbers in New Zealand List of country calling codes

References[edit]

^ "Events in Telecommunications History: 1958, 'BT's history', btplc.com/". 2008-06-18. Retrieved 2008-08-12.  ^ "Events in Telecommunications History: 1979, 'BT's history', btplc.com/". 2008-06-18. Retrieved 2008-08-12. 

External links[edit]

The archives of BT including archives of its predecessor organizations: information relating to the history of the telephone system in the UK. Archive news article from the BBC on the introduction of Subscriber Trunk Dialing BBC video of first call taking place

v t e

Telecommunications

History

Beacon Broadcasting Cable protection system Cable TV Communications satellite Computer network Drums Electrical telegraph Fax Heliographs Hydraulic telegraph Internet Mass media Mobile phone Optical telecommunication Optical telegraphy Pager Photophone Prepay mobile phone Radio Radiotelephone Satellite communications Semaphore Smartphone Smoke signals Telecommunications history Telautograph Telegraphy Teleprinter
Teleprinter
(teletype) Telephone The Telephone
Telephone
Cases Television Timeline of communication technology Undersea telegraph line Videoconferencing Videophone Videotelephony Whistled language

Pioneers

Edwin Howard Armstrong John Logie Baird Paul Baran Alexander Graham Bell Tim Berners-Lee Jagadish Chandra Bose Vint Cerf Claude Chappe Donald Davies Lee de Forest Philo Farnsworth Reginald Fessenden Elisha Gray Erna Schneider Hoover Charles K. Kao Hedy Lamarr Innocenzo Manzetti Guglielmo Marconi Antonio Meucci Radia Perlman Alexander Stepanovich Popov Johann Philipp Reis Nikola Tesla Camille Tissot Alfred Vail Charles Wheatstone Vladimir K. Zworykin

Transmission media

Coaxial cable Fiber-optic communication

Optical fiber

Free-space optical communication Molecular communication Radio waves Transmission line

Network topology and switching

Links Nodes Terminal node Network switching (circuit packet) Telephone
Telephone
exchange

Multiplexing

Space-division Frequency-division Time-division Polarization-division Orbital angular-momentum Code-division

Networks

ARPANET BITNET Cellular network Computer CYCLADES Ethernet FidoNet Internet ISDN LAN Mobile NGN NPL network Public Switched Telephone Radio Telecommunications equipment Television Telex WAN Wireless World Wide Web

Cate

.