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G
G.711 a law, G.711 μ law
Standard for a Codec.
G.711 delivers a very good voice quality that
corresponds to that in the ISDN network. As
there is little compression, the necessary
bandwidth is around 64 kbit/s per voice con-
nection, but the delay caused by coding/
decoding is only approx. 0.125 ms.
"a law" describes the European standard and
"μ law" describes the North American/Japa-
nese equivalent.
G.722
Standard for a Codec.
G.722 is a broadband language codec with a
bandwidth of 50 Hz to 7 kHz, a net transmis-
sion rate of 64 kbit/s per voice connection
and integrated speech pause recognition
and comfort noise generation (silence sup-
pression).
G.722 delivers very good voice quality. A
higher sampling rate provides clearer and
better voice quality than with other codecs
and enables a speech tone in High Definition
Sound Performance (HDSP).
G.726
Standard for a Codec.
G.726 delivers a good voice quality. It is infe-
rior to the quality with codec G.711 but bet-
ter than with G.729.
G.729A/B
Standard for a Codec.
The voice quality is more likely to be lower
with G.729A/B. As a result of the high level of
compression, the necessary bandwidth is
only around 8 kbit/s per voice connection,
but the delay is around 15 ms.
Gateway
Connects two different Networks,
e.g., a router as an Internet gateway.
For phone calls from
network, a gateway has to be connected to
the IP network and the telephone network
(gateway/VoIP provider). It forwards calls
from VoIP to the telephone network as
required.
Gateway provider
See
SIP
provider.
Global IP address
See
IP
address.
GSM
Global System for Mobile Communication
Originally, a European standard for mobile
networks. GSM can now be described as a
worldwide standard. However, in the USA
and Japan, national standards were previ-
ously more frequently supported.
H
Headset
Combination of microphone and
headphone. A headset enables a
comfortable hands free mode. Headsets that
can be connected to the base via a cable
(wire-bound) or via Bluetooth (wireless) are
available.
HTTP Proxy
Server via which the
can process their Internet traffic.
Hub
Uses one
Infrastructure network
several
Network
subscribers. All data sent to
the hub by one network subscriber is for-
warded to all network subscribers.
See also: Gateway, Router.
Glossary
VoIP
to the telephone
Network
subscribers
to connect
171
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