Telephony - Audio; Optimising Voice Quality For Voip Connections - Siemens Gigaset DX800A all in one Setup & User Manual

Telephony – Audio:

Optimising voice quality for VoIP connections

You can make general and connection-specific settings to improve the voice qual-
ity for VoIP telephony.
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Open the Settings
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.
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).
Other HDSP compatible handsets include: Gigaset S67H, S68H, SL37H.
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 G.726 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.
Both parties involved in a phone connection (caller/sender and recipient) must use
the same voice codec. The voice codec is negotiated between the sender and the
recipient when establishing a connection.
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.
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Telephony Audio Web page.
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