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Configuring the phone via the Web configurator
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Optimising voice quality for VoIP connections
Functions to improve the voice quality on VoIP connections are available on the
Web page:
Settings
¢
Telephony
¢
Audio
The voice quality for VoIP connections is mainly determined by the
voice codec
used for transferring the data and the available
bandwidth
of your DSL connection.
In the case of the voice codec, the voice data is digitalised (coded/decoded) and
compressed. A "better" codec (better voice quality) means more data needs to be
transferred, i.e., perfect voice data transfer requires a DSL connection with a larger
bandwidth.
You can influence the voice quality by selecting (bearing in mind the bandwidth of
your DSL connection) the voice codecs your phone is to use, and specifying the
order in which the codecs are to be suggested when a VoIP connection is estab-
lished.
Default settings for the codecs used are stored in your phone; one setting opti-
mised for low bandwidths and one for high bandwidths.
You can generally select one of these standard settings for all VoIP connections on
your phone. If your DSL connection has a low bandwidth, you can also exclude par-
allel VoIP connection to increase the voice quality.
You can also make the settings for the voice codecs yourself by selecting the voice
codecs to be used for each VoIP connection on your phone and specifying the
sequence in which they should be suggested when establishing a VoIP connection.
The following voice codecs are supported by your phone:
G.722
Excellent voice quality. The
broadband
speech codec
G.722
works at the same
bit rate as G.711 (64 kbit/s per speech connection) but with a higher sampling
rate. This allows higher frequencies to be played back. The speech tone is there-
fore clearer and better than for the other codecs (High Definition Sound Per-
formance).
G.711 a law
/
G.711 μ law
Excellent voice quality (comparable with ISDN). The necessary bandwidth is 64
kbit/s per voice connection.
G.726
Good voice quality (inferior to that with G.711 but better than with G.729).
Your phone supports G726 with a transmission rate of 32 kbit/s per voice con-
nection.
G.729
Average voice quality. The necessary bandwidth is less than or equal to 8 kbit/s
per voice connection.
To save additional bandwidth and transmission capacity, on VoIP connections
that use the
G.729
codec you can suppress the transmission of voice packets in
pauses ("Silence Suppression"). Instead of the background noises in your envi-
ronment, your caller then hears a synthetic noise generated in the receiver
(option:
Enable Annex B for codec G.729
).
