Technical Terms
188
DHCP
Dynamic Host Configuration Protocol
Instead of permanently assigning an IP address to a
computer in a LAN, DHCP makes it possible to
assign IP addresses dynamically and variably. Appli-
cations, which depend on an IP address, are
immediately assigned one upon request.
DDI
Direct Dial In
DDI refers to the direct dial from a telephone
network to a subscriber. Direct dial allows you to
dial specific extensions directly via this number.
DMZ
Demilitarized Zone
In the context of firewalls, a DMZ is a protected
logical network segment which contains the
publicly accessible services of a company. Thus, a
DMZ prevents external access to internal IT struc-
tures.
DNS
Domain Name Server
A server, which translates the symbolic name (e.g.
www.microsoft.com) into an IP address.
DTMF
Dual Tone Multi Frequency
Seven different frequencies and additional mixture
frequencies are transmitted in the telephone line in
order to clearly communicate the activated button.
DSP
Digital Signal Processor
Direct
Dialing-In
line
ISDN line, to which a telecommunications system
with so-called extension numbers is connected,
which can be used to directly contact a subscriber.
In the case of the number “(0231) 4777-227, “227” is
the extension number within a telecommunications
system. An extension number allows you to dial a
specific extension of a telecommunications system
directly via this defined number.
E.164
ITU-T standard for global telephone numbering
(country code, local area code and subscriber
number, e.g.+49 (231) 123456-789.
Term
Explanation
ENUM
tElephone NUmber Mapping
ENUM is an application of the Domain Name System
for converting telephone numbers (in the E.164
format) to Internet addresses. An ENUM registration
of a VoIP number allows calls to be placed directly
via the Internet, for example.
Ethernet
Network for limited local operation (10 m to 10 km)
in the LAN. The individual PCs are connected via a
cable network. Data is transferred within this
network at a rate of 10Mbit/s, 100Mbit/s or 1Gbit/s.
FD
Full Duplex (DX, sometimes also FDX, permits simul-
taneous transmission of information in both direc-
tion, e.g. in telephony)
FTP
File Transfer Protocol (Network protocol for file
transmission)
G.711
ITU standard for compression,
here: Audicodec 64 kbit/s
G.722
ITU standard for compression,
here: Audicodec 64 kbit/s
G.723.1
ITU standard for compression,
here: Audiocodec 5.3 kbit/s and 6.3 kbit/s
G.729
ITU standard for compression,
here: Audicodec 8 kbit/s
GAP
Generic Access Protocol
Standard for DECT Handsets, which allows the
communication between handsets and basis
stations of different manufacturers.
Gateway
A gateway is a system, which connects two different
networks and which can transfer the data in one
network to the other network and vice versa. This
means that the physical networks can be different
and the protocols used (e.g. IP network and ISDN)
can also be different.
Term
Explanation
