Siemens Gigaset S675IP User Manual page 144

G
G.711 a law, G.711 µ law
Standard for a Codec.
G.711 delivers a very good voice qual-
ity that corresponds to that in the ISDN
fixed line. As there is little compression,
the necessary bandwidth is around 64
kbit/s per voice connection, but the
delay caused by coding/decoding is
only 0.125 ms.
"a law" describes the European stand-
ard and "µ law" describes the North
American/Japanese 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 transfer rate of 64 kbit/s per lan-
guage connection and integrated
speech pause recognition and comfort
noise generation (silence suppression).
G.722 delivers very good voice quality.
A higher sampling rate provides clearer
and better voice quality than 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
inferior to the quality with codec G.711
but better than with G.729.
G.729A/B
Standard for a Codec.
The voice quality is rather lower with
G.729A/B. As a result of the high level
of compression, the necessary band-
width 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 VoIP to the tele-
phone network, a gateway has to be
connected to the IP network and the
telephone network (gateway/VoIP pro-
vider). 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, European standard for
mobile networks. GSM can now be
described as a worldwide standard. In
the USA and Japan national standards
are now more frequently supported
than in the past.
H
Headset
Combination of microphone and head-
phone. A headset makes handsfree
talking more convenient. There are
headsets available that are connected
to the handset by a cable.
HTTP proxy
Server via which the Network sub-
scribers can process their Internet traf-
fic.
Hub
Uses one Infrastructure network to
connect several Network subscribers.
All data sent to the hub by one network
subscriber is forwarded to all network
subscribers.
See also: Gateway, Router.
Glossary
143