C-2
Appendix
C
Glossary
the subscriber at the receiving end lifts the phone (in the
Off-Hook
status), the call begins. The
call is ended when either subscriber replaces the phone (in the
On-Hook
status).
Digital Signal Processor
Digital Signal Processor ((DSP
DSP))
A special computer chip designed to handle digital signals, which are fast and complex. It is
widely used for real-time processing of voice and image.
Dual Tone Multi Frequency
Dual Tone Multi Frequency ((DTMF
DTMF) )
An in-band signaling system that uses two simultaneous voice-band tones for dialing.
Dynamic Host Configuration Protocol
Dynamic Host Configuration Protocol ((DHCP
DHCP))
Provides a mechanism for allocating
IP Addresses
dynamically so that addresses can be reused
when hosts no longer need them.
E.164
E.164
The international numbering system for remote communication using telephone.
EE&M
&M ((Ear & Mouth
Ear & Mouth)) Signaling
Signaling
A method of sending and monitoring signals between signaling equipment independent of trunk
devices. E (Ear) receives open or earth signals from signaling equipment. M (Mouth) sends earth
signals or voltage status. It monitors a PBX’s status depending on the changes in voltage of E and
M. It also connects or disconnects connections.
Echo Cancellation
Echo Cancellation
A process of removing echo from lines. Echo normally is created due to difference in impedance
in wires of a telephone network. Echo Cancellers store a voice sample it sends, and extracts the
voice from the returned voice in the reverse direction.
Fast Start
Fast Start
Fast Start is one of the
H.323
signal methods. It exchanges all information through a connection at
the connection stage, and the media connection is made without connecting to
H.245
. As it is
faster and simpler than Slow Start, it is now more widely used.
