LINKS
Abbreviations
Glossary
Standards
2G
A
circuit-switched technology used in mobile telephone networks where the
communication link between handsets and base stations is digital — in
earlier telephone networks (1G), the communication link was analogue. The
most popular standard for 2G is GSM, and most GSM networks operate in the
900MHz and 1800MHz bands. An enhancement of the 2G technology added
packet-switching capability and higher speeds to support data communications — commonly but
not officially known as 2.5G
3G
The third
generation technology
used in mobile telephone networks — it offers higher data speeds (up
to 7Mb/s) and support
for multimedia applications including video
4G
The fourth generation technology
used in mobile telephone networks — it provides a packet environment
for both voice and data traffic, offering data speeds up to 100Mb/s
Asynchronous
An asynchronous system is a
system employing start and stop elements for individual synchronisation of
each information character, word or block
Basic Rate Access / Interface
An ISDN service
providing two B channels (each of 64kb/s) and one D channel (16kb/s).
The B channels may each carry voice or data, and may be bonded to provide
128kb/s throughput. The D
channel is typically used for control/signalling but may be used for data
purposes
Baud
A unit of rate
of change of signal conditions in digital transmission
Bit
A contraction of
binary digit, a bit is the smallest possible unit of information making up a
character or word of digital code
Bit Rate
The speed at which bits are transferred (in bits per second).
Bit rate can be, but isn't necessarily, the same as baud
Block Wiring
When used in telephony, block
wiring refers to the cabling system between, usually, the Main Distribution
Frame (MDF), and the Distribution Points (DP). See also Floor Wiring
Blower
I always thought
this expression referred to a telephone, but to read an interesting
explanation of its derivation, click
here
Break-In
Break-in is when a call from
the PSTN enters a Private Network and is routed to an extension at a site
other than the site at which the call first entered the Network. Break-in
allows callers to circumvent the PSTN and make long-distance calls at local
call rates
Break-Out
Break-out is when a Private
Network call exits to the PSTN at a site other than the site at which the
call originates. Thus, long-distance calls can be carried by the Private
Network and passed to the PSTN at the Network node nearest to the
destination, avoiding long-distance charges
Bridge
The equipment or techniques
used to match circuits to each other ensuring minimal transmission
impairment. Bridges are commonly used to connect LANs to PTO circuits or to
each other
Broadband
A transmission capacity greater than ISDN Primary Rate (ITU
I.113)
or
A transmission system where multiple data streams are transferred
simultaneously via a single medium
Byte
A fixed number of Bits (nowadays, eight is assumed) in a
contiguous sequence forming a character or
word of digital code
C7
The ITU-T Signalling System Number 7
Call Logging
The recording of the full
statistics of a telephone call, such as the call start time, dialled number,
call duration, call end time, etc. Most PABXs are capable of recording the
call statistics but are not able to arrange the data into useful reports.
This latter task is undertaken by a separate call logger
Calling Line Identification (CLI)
A network facility that enables the number from which a call
is made, or the number to which a call may be returned, to be identified
Carrier Pre-selection (CPS)
A facility that allows end
users to opt for certain defined classes of outgoing calls to be carried by
an operator selected in advance (and having a contract with the customer).
CPS avoids the end user having to dial a routing prefix or some other
procedure to force a particular routing
Cellular Networks
A fully automatic, wide-area,
mobile radio-telephone system comprising groups of coverage areas called
cells. The five UK mobile network operators are 3, O2,
Orange, T-Mobile and Vodafone
Digital Access Signalling System 2 (DASS2)
A message-based signalling
system developed by British Telecom, primarily to interconnect private
networks and the UK's PSTN. DASS offers fast call set-up, features such as
Calling Line Identification and switched data transmission at 64kb/s
Digital Private Network Signalling System (DPNSS)
DPNSS is a UK developed
standard for interconnecting digital PABXs, which has found some popularity
abroad. It offers many enhanced cross-network features to users
Duplex
A system supporting two-way
communications. Half-Duplex provides non-simultaneous communications (e.g, a
basic intercom system) whereas Full-Duplex provides simultaneous
communications (telephone networks)
Electronic Data Interchange (EDI)
A method of interchanging
information (such as orders and invoices) between organisations by totally
electronic means
Erlang
A measure of call traffic. One
Erlang is equivalent to one call occupying one communication channel for one
hour
Ethernet
Ethernet is one method by
which devices on a LAN may communicate which each other. It's very polite —
it listens out for activity before attempting communication. It operates at
transmission speeds up to 1Gb/s
Femtocell
A mobile base
station located in your home, or small business premises, that connects to
your Internet service. It offers better coverage within the site and
seamless hand-over if you leave whilst on a call
Find-me-anywhere services
These services enable end
users to be contacted, whatever their location, where the call charge is not
distance dependent. Mobile, personal numbering and paging services in the UK
use the ‘07’ range
Floor Wiring
When used in telephony, floor wiring refers to the
cabling system between, usually, the Distribution Point (DP) and the Telecom
Outlet. See also Block Wiring
Grade of Service (GoS)
The GoS of a particular part
of a telephone system is a measure of how frequently calls fail due to
congestion. It is usually expressed as the probability of a call meeting a
busy condition due to congestion of circuits or equipment (e.g, a GoS of 0.01
means that the probability is, on average, that one call will fail in every
one hundred call
attempts
Integrated Services Digital Network (ISDN)
The ISDN is a totally digital
network, able to offer access for a range of services (voice, data, high
speed facsimile, video-conferencing) via a single subscriber interface. The
channel bandwidth is 64kb/s
Interactive Voice Response (IVR)
A telephone
technology that allows a caller, using either voice or tones, to make a
selection from set a pre-recorded choices
ITU Telecommunications Standardisation Sector (ITU-T)
The ITU-T is a permanent organ
of the International Telecommunication Union (ITU), the United Nation’s
specialised agency in the field of telecommunications. It is responsible for
devising and proposing recommendations on technical, operating and tariff
matters with a view to standardising telecommunications on a world-wide
basis
Local Area Network (LAN)
A network controlled by a
private switching system which carries data traffic between connected
devices within a limited geographical area, e.g, within a single site
Long-Term Evolution (LTE)
A set of
enhancements to UMTS providing a flat all-IP network that offers higher
through-put (peak data down- and up-link rates of 100Mb/s and 50Mb/s
respectively) with low latency
Modem
(from modulator-demodulator)
A device
that modulates digital input signals onto a carrier for transmission via
cable or radio systems. It is commonly used to transmit and receive data via
an analogue telephone interface
Multiplexor (or mux)
A device that combines and
converts multiple inputs into a single output. A demultiplexor does the
opposite
Networking Code of Practice (NCoP)
The NCoP is a Code of Practice
issued by the Office for Telecommunications (OFTEL), to ensure that private
networks are designed in such a way that calls to and from the PSTN meet
internationally agreed standards
Number Portability
A facility whereby subscribers
can retain their number regardless of the organisation providing the
telephone service
Numbering Plan
A set of numbers defining
access to services (extensions, trunks, facilities) on a telephone system or
network
Open Systems Interconnection (OSI)
OSI is the set of
internationally-agreed standards by which Open Systems should communicate.
The goal of OSI is to permit the flow of information irrespective of the
equipment or transmission media in use
Personal Numbering Services (PNS)
This is a service, based on
number translation, that allows end users to be called using a single
personal telephone number, and to receive such calls at any telephone number
they specify
Prefix, National or
International
A prefix is one or more digits used to
indicate that the digits following are from a different geographic area or
another part of the numbering plan than the originating number. Examples are
‘0’ (the UK's national dialling prefix) and ‘00’ (the UK's prefix to access
other countries)
Premium Rate Services
(PRS)
Services paid for via the
telephone bill of a subscriber, and charged at rates above those for Special
Services. The revenue for a PRS call may be shared between the operator and
the provider of the service
Primary Rate Access / Interface
An ISDN service providing
multiple B channels (23 in N America & Japan, 30 elsewhere) and one D
channel. Each channel provides a bit rate of 64kb/s; the B channels may each
carry voice or data, and the D channel is typically used for control /
signalling purposes
Private Automatic Branch Exchange (PABX)
PABX is a general term used to
describe all private automatic telephone exchanges that are connected to the
PSTN
Private Circuit / Wire
A Private Circuit is a circuit
that is rented from a PTO for the customer's dedicated use. The tariffs for
such a circuit are typically based on the circuit's performance
specification and the distance between the sites; individual
calls/connections are not charged for
Public Switched Telephone Network (PSTN)
The worldwide network to which
most business and residential telephones are connected
Public Telecommunications
Operator (PTO)
A PTO is a company licensed to offer and provide basic
telecommunications services to the general public. Specifically, only PTOs
may provide transmission facilities between sites (except over very short
distances). Examples of PTOs are British Telecom, Cable & Wireless, Colt
Telecom, ntl and Thus
Simplex
A system supporting
one-way communications only, e.g, a broadcast network
Special Services
Services paid for via the
telephone bill of a subscriber, and charged at special rates, from free up
to, and including, national rate. Charges for these calls can be paid by the
called party, shared between the caller and the called party, or paid wholly
by the caller
Specific Absorption Rate (SAR)
Specific Absorption Rate is
the unit of measurement for the amount of radio frequency energy absorbed by
the body when using a mobile phone
Synchronous
A synchronous system is a
system in which all the components of that system are controlled by a single
timing source
System X and System Y
A range of computer-controlled
telephone exchanges used in the UK PSTN . to switch and transmit digital
signals
Tandem
A Tandem exchange is an
exchange provided to switch through traffic — it has no
subscribers/extensions
Traffic Report
Most large PABXs are able to
provide a basic report regarding the utilisation of Trunks and, in some
cases, system resources. This report, called a Traffic Report, is the only
way to accurately identify congestion within the system
Universal Mobile Telecommunications System
(UMTS)
A et of
technology standards for 3G mobile networks
Voice over Internet Protocol (VoIP)
A technology
allowing voice telephony calls over public or private IP infrastructures
Wide Area Network (WAN)
A WAN is normally taken to be
a network where PTO services are required to interconnect different sites. A
WAN may be local (connecting different sites), regional, national or
international
X.25
Specifically, X.25 is the ITU
standard protocol for the communications link between a packet-mode data
terminal and a packet-switched network, however the term usually includes
the switching network also
Page updated 06/08/2013