ACRONYMS USED IN THIS RECOMMENDATION

ABM Asynchronous Balanced Mode (of HDLC)
ACK Acknowledgement
ADPCM Adaptive Differential Pulse Code Modulation
AFI Authority and Format Identifier
ARM Asynchronous Response Mode (of HDLC)
AU Access Unit
BC Bearer Capability
BCD Binary Coded Decimal
Bi Indicated B-channel
Bi' An idle B-channel Bi
Bj A B-Channel in use
CEI Connection Endpoint Identifier
CES Connection Endpoint Suffix
CSPDN Circuit Switched Public Data Network
D The D-channel
DDI Direct-Dialling-In
DLCI Data Link Connection Identifier (see Recommendations Q.920 and Q.921)
DME Digital Multiplexing Equipment
DSP Domain Specific Part
DTE Data Terminal Equipment
HDLC High Level Data Link Control (procedures)
HLC High Layer Compatibility
I Information (frame)
IA5 International Alphabet No. 5 (defined by ITU-T)
IDI Initial Domain Identifier
IE Information Element
IEC International Electrotechnical Commission
ISDN Integrated Services Digital Network
ISO International Organization for Standardization
ISUP ISDN User Part
IWF Interworking Function
IWU Interworking Unit
LAN Local Area Network
LAPB Link Access Protocol-Balanced
LAPD Link Access Protocol on the D-channel
LLC Low Layer Compatibility
LLI Logical Link Identifier (see Recommendation Q.921)
LVC Low-bit-rate Voice CODEC
NACK Negative Acknowledgement
NIC Network Independent Clock
NRM Normal Response Mode (of HDLC)
NSAP Network Service Access Point
NT2 Network Termination of type two
OSI Open Systems Interconnection
PABX Private Automatic Branch Exchange
PCM Pulse Code Modulation
PH Packet Handler
PSPDN Packet Switched Public Data Network
PSTN Public Switched Telephone Network
PVC Permanent Virtual Circuit
RDTD Restricted Differential Time Delay
RSC Restart confirmation
RSI Restart indication
RSR Restart request
SABME Set Asynchronous Balanced Mode Extended (frame)
SAPI Service Access Point Identifier (see Recommendation Q.921)
SDL Specification and Description Language
TA Terminal Adaptor (see Recommendation I.411)
TE1 Terminal Equipment of type 1 (see Recommendation I.411)
TE2 Terminal Equipment of type 2 (see Recommendation I.411)
TEI Terminal Endpoint Identifier (see Recommendations Q.920 and Q.921)
TID Terminal identifier
UDI Unrestricted Digital Information
UDI-TA Unrestricted Digital Information with Tones/Announcements
UI Unnumbered Information (frame)
USID User Service Identificator
VC (Switched) Virtual Circuit