Specifications

Glossary
353
routers at Layer 3 to direct the data to an appropriate queue. Value 46 is recommended for
voice and will use the Expedited Forwarding queue or Class of Service.
DSP – Digital Signal Processor. This is a programmable device that can manipulate signals,
such as audio, to generate and detect a range of signals, e.g. DTMF signalling.
DSU – Digital Service Unit. A peripheral which provides digital ports for the ICP.
DTMF – Dual Tone Multi-Frequency. In-voice-band tones used by telephones to signal a
particular dialed digit. Also known as touch tone.
E – Erlang. A measure of usage of a resource, e.g. 0.75e = 75%. 1 e = 36 CCS.
E1 – Primary Rate running at 2.048 Mbps providing 30 channels of voice of PCM.
E2T – Ethernet to TDM. This is the conversion of voice streaming between TDM and IP.
E911 – Enhanced 911 (Emergency Services). Also 999 (UK) and 112 (International).
eMOH – Embedded Music On Hold.
ESM – Embedded System Management. Means to program a system from the System
Administration Tool, Group Administration Tool, or Desktop Tool.
FAX – Facsimile. A means of transmitting printed text or picture information with acoustic tones
FIM – Fiber Interface Module. A fibre optic TDM interface module used to connect the ICP to
various peripherals.
FTP – File Transfer Protocol. An electronic method to transfer file information.
G.711 – PCM Voice Streaming. ITU standard for conversion of voice-streaming to digital PCM
(64 kbps).
G.729 – Voice Streaming CODEC. Reduced bit rate from G.711 (8 kbit/s)
Gateway – A path between different media streaming technologies, in this case between TDM
and IP.
Group Controller – The call control of the ICP is in control of a number of units, where the
functions are more dedicated, e.g. to a separate gateway
GRP – Gateway Routing Protocol. A generic term which refers to routing protocols.
HSRP – Hot Standby Routing Protocol. A Cisco proprietary protocol used to increase
availability of default gateways used by end hosts.
ICMP – Internet Control Message Protocol. Messages to help identify when devices are
present and create warnings when they fail.