This is the glossary for Asterisk vs ISDN. Last Update: 2020-03-29

 


ISDN
Integrated Services Digital Network

Signalling Protocols


1TR6
D-channel protocol used in Germany, obsolete

1TR67
German implementation of the DSS1 D-channel protocol

4ESS
D-channel protocol used in the USA by AT&T, PRI only

5ESS
D-channel protocol used in the USA by AT&T, Alcatel-Lucent

AP IX-123-E
D-channel protocol used in Australia, obsolete

ARINC 764
ARINC Characteristic 746-4 1996-04
Communication protocol used for passenger airplanes, based on Q.931 (GTE, AT&T)

BTNR 191
D-channel protocol used in the UK, obsolete

cornet
D-channel protocol used by Siemens HiPath (HiCom/OfficeCom) / unify OpenScape in various flavours

CSN-7
Unknown D-channel protocol used in China

CT1
D-channel protocol used in Belgium

DASS2
DASS-2
D-channel protocol used in the UK, PRI only

DGT
D-channel protocol used in Taiwan

DKZE
=DKZ-E
=12TR7
Digitale KennZeichengabe auf Endstellenleitungen
Standard D-channel protocol for PABx extensions, successor of DKZN1
Uses both elements of 1TR6 and DSS1

DKZN1
Unknown D-channel protocol by Deutsche Telekom

DKZN2
Unknown D-channel protocol by CCITT, ZVEI and others
"Closer to DSS1"

DPNSS1
=BTNR 188 1995-01
Digital Private Network Signalling System No. 1
A British Telecom standard for crossconnecting PBXs via E1

DMS-100
D-channel protocol used in the USA, Nortel Networks implementation of NI-1

DMS-250
D-channel protocol used in the USA, Nortel Networks

DSS1
DSS-1
Digital Subscriber Signalling System #1
D-channel protocol as specified by ETSI ETS 300 102
Also known als Euro-ISDN, NET3 (BRI) or NET5 (PRI)
Has superseded most of the national standards and is now used in most parts of the world
Europe, Australia, Brazil, Iran, India, Israel, New Zealand, Peru, Singapore, South Africa, Sri Lanka, Taiwan, Palestine and United Arab Emirates

DSS2
DSS-2
Digital Subscriber Signalling System #2
ITU-T Q.2931
D-channel protocol for use in ATM broadband networks

EXPO-92
unknown D-channel protocol used in Spain

INS64
D-channel protocol used by NTT in Japan, BRI only

INS1500
D-channel protocol used by NTT in Japan, PRI only

KDD
D-channel protocol used in Japan

NI-1
National ISDN 1
D-channel protocol used in the USA by Bellcore
This version had no D-channel and used RBS instead, limiting data transfer on the B-channels to 56kbps

NI-2
National ISDN 2
D-channel protocol used in the USA by Bellcore

NI-3
National ISDN 3
D-channel protocol used in the USA

PSS1
QSIG
=ISO/IEC 11572 1995
Private Signalling System #1
D-channel protocol used between PINXs in a PISN, based on DSS-1
See also: http://www.ecma-international.org/activities/Communications/QSIG_page.htm

PTT 840.73.2 1995-06
=SwissNet
Swiss Telecom PTT implementation of DSS-1

TNET
proprietary D-channel protocol used by Tenovis

TS.013
=TPH 1962
D-channel protocol used in Australia, BRI only, obsolete

TS.014
=TPH 1856
D-channel protocol used in Australia, PRI only, obsolete

TSO14
D-channel protocol used in Australia (Austel), PRI only, similar to DSS1

VN2
D-channel protocol used in France, obsolete

VN3
D-channel protocol used in France, obsolete

VN4
D-channel protocol used in France, obsolete

VN5
D-channel protocol used in France

VN6
D-channel protocol used in France

GSM
The Globals System for Mobile Communication
The well know PLMN

Interfaces


BRI
Basic Rate Interface
Defined in ITU-T I.430
Also known as ISDN2, 2B+D or BRA
This interface carries 2 B-channels and a D-channel

PRI
Primay Rate Interface
Defined in ITU-T I.431
Also known as ISDN30, PMX or PRA
This exists in two different Versions:
PRI over T1 (North America) or J1 (Japan) with 23 B-channels and a D-channel
PRI over E1 (Europe / rest of the world) with 30 B-channels and a D-channel

NFAS
Non-Facility Associated Signalling
Multiple interfaces sharing one common D-channel
Additional backup D-channels may be present

B-channel
Bearer Channel
64kbps full duplex channel carrying circuit switched end-to-end payload

D-channel
Data Channel
This channel carries signalling information between the subscriber and the central office.
Can additionally also carry packet switched payload like X.25 data, called X.31
64kbps on PRI, 16kbps on BRI

H-Channel
Aggregated B-channels

H0-Channel
384 kbit/s channel (6 B-channels)

H10-Channel
1472kbit/s channel (23 B-channels)

H11-Channel
1536 kbit/s channel (24 B-channels)

H12-Channel
1920 kbit/s channel (30 B-channels)

ptp
Point To Point
T reference point, 4-wire access for a single terminal to a line
An interface in ptp mode usually implies the use of DDI

ptmp
Point To Multi Point
S reference point, 4-wire bus allowing multiple terminals concurrent access to a line.
Only available on BRI
An interface in ptmp mode usually implies the use of MSNs

TE
Terminal Equipment
An ISDN Telephone or PBX, usually connects to an NT via the S/T-interface
Some TE, namely PC interfaces, can be operated in NT-mode as well

TE1
Terminal Equipment 1
A terminal that connects to the T-interface

TE2
Terminal Equipment 2
A terminal that connects to the S-interface

NT
Network Terminator
The device converting from the U-interface to the S/T-interface, providing network access to TEs

NT1
Converts from the U-interface to the T-interface, providing network access to one TE

NT2
Converts from the T-interface to the S-interface, providing network access to one or more TE

NT1/2
Converts from the U-interface to the S-interface
That's the most usual device in use and forms the demarcation point in many countries

R-interface
R reference point
Actually beyond the ISDN. This term is used for any interface between some ISDN terminal adapter and an non-ISDN CPE
e.g. a V.24 port on a data adapter (often wrongly calld "ISDN modem") or the FXS port on a POTS adapter

S-interface
S reference point
4-wire bus by which ISDN TE such as Phones, terminal adaptors or PBXs are connected to an NT2 or NT1/2
The bus provides TEI management for access by multiple devices (ptmp)
In practice no difference is made between the S and T-interfaces and they are often referenced as S/T-interface

S0
S-interface with 0 (full) megabit, i.e. on a BRI
4-wire bus (2 Rx, 2 Tx) transmitting 192kbps. usually using an 8p4c modular plug
Two more pairs may be preset for power supply, but usually it carries phantom power on the data lines

S2m
S-interface with (about) 2mbit, i.e. on a PRI (2048kbps E1 or 1544kbps T1/J1)

T-interface
T reference point
4-wire bus by which ISDN TE such as a PBX or NAS or an NT2 are connected to an NT1
The T-interface does not provide TEI management, so only one device can be connected (ptp)
In practice no difference is made between the S and T-interfaces and they are often referenced as S/T-interface

U-interface
U reference point
This is the line from the Central Office to the customer where it is terminated by an NT

Uk0
U-interface with 0 (full) mbit, i.e. on a BRI
2-wire interface transmitting 160kbps full duplex with echo compensation
This is used from the central office (line termination) to the customers premises (demarcation point/NT)
The line usually carries about 90V DC (or low power around 60V DC) to power the NT and one phone in restricted/emergency mode
For details see line code below

Up0
U-interface with 0 (full) mbit, i.e. on a BRI
2-wire interface transmitting 320kbps half duplex ("ping-pong")
Typical maximum length is around 500-1000m, but up tp 4km possible
This is usually used from PBXs to proprietary/system phones or NTs

line code
At the U-interface
The 160kbit of a BRI are transmitted in one of the following ways:
namespecificationsymbolsmax. distanceterminationextrasoccurance
MMMS43
4B3T 		G.961 Appendix I
ETSI TS 102 080 Annex B
1TR220 		4 bits in 3 ternary symbols
at 120kbaud FDX 		4.2km@0.4mm
8.2km@0.6mm 		150ohm most parts
of the world
2B1Q G.961 Appendix II
ETSI TS 102 080 Annex A
ANSI T1.601 		2 bits in a quatenary symbol
at 80kbaud FDX 		5.5km 135ohm North America
Italy
Switzerland
TCM/AMI G.961 Appendix III 1 bit in a ternary symbol
at 320kbaud HDX 		CRC-12 over
4 frames 		Japan
SU32 3B2T G.961 Appendix IV 3 bits in two ternary symbols
at 108kbaud FDX 		CRC-15 over
16 frames

 

Features / Supplementary Service


CLIP
Calling Line Identification Presentation
Dispaly of the callers number at the callees phone

CLIR
Calling Line Identification restriction
Prevents the callers number being shown to the callee

CLIRO
Calling Line Identification restriction override
Display of all caller IDs, regardless of CLIR

COLP
Connected Line Identification Presentation
Displays the number of who actually answered the call to the caller

COLR
Connected Line Identification Restriction
Prevents the number of who actually answered a call being displayed to the caller

ACR
Anonymous Call Rejection
Automatic rejection of calls with CLIR

AOC
Advice Of Charge

AOC-S
AOCS
Advice Of Charge at Setup
Displays call charges when the call is being placed

AOC-D
AOCD
Advice Of Charge During call
Displays call charges while in conversation

AOC-E
AOCE
Advice Of Charge at call End
Displays call charges when the call is disconnected
This can also transport charging information for calls that have not been active on the interface, like calls forwarded at the CO

AOC-R
AOCR
Advice Of Charge Request
Request AOC information on a per-call basis

Call Diversion services


CF
Call Forwarding

CFU
Call Forward Unconditional

CFB
Call Forward when Busy

CFNR
CFNRy (GSM)
Call Forward when No Reply
... if the subscriber was alerted but did not answer within a given time (dealyed forwarding)
Sometimes called CFD or CFNA (Cisco)

CFALD
CFNRc (GSM)
Call Forward if All Lines Disturbed
... if the line has failed or a mobile subscriber cannot be reached
Sometimes called CFNREA (Not REAchable), CFNA (Not Available) or CFSS (Station out of Service)

SCF
Selective Call Forwarding

SCFU
Selective Call Forward Unconditional

SCFB
Selective Call Forward when Busy

SCFNR
Slective Call Forward when No Reply

CFSAE
Call Forward to Short Announcement Equipment

CFTA
Call Forward to Telephone Announcement

CFFA
Call Forward to Fixed Anouncements

CD
Call Deflection
Allows forwarding of a call while it is already ringing

CFP
Call Forward Parallel
Forwards a call to an additional destination while still signalling it at the original destination

SCFP
Slective Call Forward Parallel

CDO
Call Diversion Override
Ignore active CF or CD

IIFC
Inhibition of Incomming Forwarded Calls
Reject forwarded calls

SCR
Selective Call Reject

CB
Call Barring

ICB
Incoming Call Barring

SICB
Selective Incoming Call Barring

OCB
Outgoing Call Barring

3PTY
3 ParTY call
The (smallest possible) conference that can be controlled from almost all phones

CW
Call Waiting
Signalling of further calls even if no free channel available

TP
Terminal Portability
Moving a TE to another physical connection i.e. unplugging and replugging the phone without interrupting an ongoing call
Often referred to as parking

CT
Call Transfer

ECT
Explicit Call Transfer

CCBS
Completion of Call to Busy Subscribers
Automatic call back when the called party is no longer busy

CCNR
Completion of Call if No Reply
Automatic call back when the called party has been busy

MWI
Message Waiting Indication

UUS
User-to-User Signalling

MSN
Multiple Subscriber Number
A fixed set of telephone numbers assigned to the interface
An incomming call will always immediately contain the complete called number
The use of MSN usually implies an interface in ptmp mode
This is the opposite of using DDI

DDI
Direct-Dialling-In
A base telephone number assigned to an interface
Additional digits dialled by the caller are sent to the user transparently
Matching extensions are defined in the CPE and may have different lengths
An incomming call might contain only part of the called number with additional digits following later as the caller dials them
DDIs are processed and validated by the CPE
The use of DDI usually implies one or more interfaces in ptp mode
This is the opposite of using MSNs

SUB
SUBaddressing
Both calling and called party numbers can have an additional subaddress in BCD format

CUG
Closed User Group

Various / unsorted


TEI
Terminal Endpoint Identifier
In ptmp lines dynamically assigned address (64-126) for signalling information from/to a specific device on the bus
Fixed TEIs available from 0-63, usually 0 is ued for PBXs in ptp lines

CAPI
Common ISDN Programming Interface
Industy standard for a hardware independent access to the network.
Originally designed for MS-DOS/Windows and has since been introduced to various operation systems
Also part of the standard Linux Kernel.
See also: www.capi.org

Asterisk
The famous telephony tool-kit
See also: www.asterisk.org

Digium
The driving force of the Asterisk project
Manufactures hardware interfaces and SIP phones for use with Asterisk
They also sell software modules, Asterisk based appliances and support
See also: www.digium.com

Zaptel
Has been renamed to DAHDI

DAHDI
Digium Asterisk Hardware Device Interface
Telephony hardware drivers and Asterisk channel driver architecture
Formerly known as Zaptel

LCR
Linux-Call-Router
A software PBX sitting on top of misdn2
Was formerly known as PBX4Linux
See also: www.Linux-Call-Router.de

PABX
Private Automatic Branch Exchange

PBX
Private Branch Exchange
A (not necessarily) small telephone switch for home, office or campus use

PINX
Private Integrated Network eXchange
(Used in PSS1:) A part of a PISN, e.g. a PBX

PISN
Private Integrated Services Network
(Used in PSS1:) A private network of PINXs like e.g. PBXs

POTS
Plain Old Telephone Service
Analogue telephony service, much unchanged in the last centuries

PSTN
Public Switched Telephone Network
Before the 1980s it was just the telephone network
Since then it meant ISDN in more and more countries and the former technology became known as POTS

PLMN
Public Land Mobile Network
e.g. LTE, UMTS, GSM, AMPS, NMT

TE-mode
An ISDN device acting as a TE, i.e. requiring access to the ISDN

NT-mode
An ISDN device acting as a NT, i.e. providing access to the ISDN

DECT
Digital Enhanced Cordless Telecommunications
formerly known as Digital European Cordless Telephony

CAT-iq
Cordless Advanced Technology - internet and quality
Advanced version of DECT with better interoperability between devices from different manufacurers and G.722 in addition to G.726

BC
Bearer Capability
The kind of connection requested.
e.g. speech, video or raw data

HLC
High Layer Compatibility
Information specifying the desired type of service, like e.g. telephony

LLC
Low Layer Compatibility
Information specifying the desired coding of information, like e.g. V.110

MCID
Malicious Call IDentification

CODECs


G.711
Voice CODEC with 8000 samples/second, 12 bit/sample reduced down to 8 bit/sample
uses either a-law or µ-law, giving a rate of 64kbps/s
This ist the standard CODEC used in the PSTN

a-law
PCMA
G.711A
Variant of the G.711 codec used in Europe

µ-law
PCMU
G.711U
Variant of the G.711 codec used in North America

G.718
Voice CODEC with 8000 or 16000 samples/second reduced using CELP/MDCT
Available rates: 8, 12, 16, 24 and 32 kbit/s

G.719
Wideband audio CODEC with 48000 samples/second, reduced to 32 to 128 kbit/s
Most common bit rates are 32, 48 and 64 kbit/s, but any rate in that range in 4 kbit/s steps is possible
Uses technology from the Siren CODECs

G.721
Voice CODEC with 8000 samples/second reduced to 32 kbit/s by ADPCM
Superseeded by G.726

G.722
Wideband voice CODEC with 16000 samples/second, reduced to 48, 56 or (usually) 64 kbit/s using ADPCM
This CODEC is available as an alternative to G.711 in the ISDN, but was hardly ever used
Note that G.722, G.722.1 and G.722.2 are completely different codecs and are not backwards compatible.

G.722.1
Siren-7
Wideband voice CODEC with 16000 samples/second, reduced to 24 or 32 kbit/s
G.722.1C (mono version of Siren 14) uses 32000 samples/second at 24, 32 or 48 kbit/s

Siren-14
Wideband voice CODEC with 32000 samples/second, reduced to 24, 32 or 48 kbit/s mono or 48, 64 or 96 kbit/s stereo
The mono version became G.722.1C

Siren-22
Wideband voice CODEC with 48000 samples/second, reduced to 32, 48 or 64 kbit/s mono or 64, 96 or 128 kbit/s stereo
An improved version came up as G.719

AMR
Adaptive Multi-Rate
Voice CODEC with 8000 samples/second reduced by ACELP
Available rates: 1800, 4750, 5150, 5900, 6700, 7400, 7950, 10200 or 12200 bit/s

G.722.2
AMR-WB
Adaptive Multi-Rate WideBand
Wideband voice CODEC with 16000 samples/second reduced by ACELP
can operate at 6.60, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 or 23.85 kbit/s

AMR-WB+
Extended Adaptive Multi-Rate WideBand
Wideband audio CODEC using ACELP
reduced to 5.2 to 36 kbit/s mono or 6.2 to 48 kbit/s stereo

G.723
Voice CODEC with 8000 samples/second reduced to 24 or 40 kbit/s using ADPCM
Superseeded by G.726
Note that G.723 and G.723.1 are completely different codecs and are not backwards compatible.

G.723.1
Voice CODEC with 8000 samples/second reduced to 6.3 kbit/s by MPC-MLQ or 5.3 kbit/s using ACELP

G.726
Voice CODEC with 8000 samples/second reduced to 16, 24, 32 or 40 kbit/s
Successor to G.721 and G.723
The 32kbps version is the standard CODEC for DECT phones

G.728
Voice CODEC with 8000 sampels/second reduced to 16 kbit/s using LD-CELP
G.728 has a verly low coding delay of only 5 samples (0.625 ms)

G.729
Voice CODEC with 8000 sampels/second reduced to 6.4, 11.8 or (usually) 8 kbit/s
G.729A has a reduced complexity, saving CPU time at slightly reduced speech quality while being backwards compatible
G.729B Adds silence detection and uses discontinous transmission/comfort noise generation

G.729.1
G.729J
G.729EV
G.729 compatible voice CODEC with 8000 or 16000 sampels/second
Available rates: 8 or 12 kbit/s for 8000s/s or 14 ro 32 kbit/s for 16000s/s

DTMF
Dual Tone Multi Frequency
Signalling tones (for "touchtone" dialling) as defined in Q.23