Voice Coding; Dtmf Handling; Voice Quality - Siemens HiPath 3000 Series Service Documentation

h3h5_in_the_lan.fm
HiPath 3000/5000 in the LAN Network
HG 1500 Board
13.6.4.2

Voice Coding

HiPath 3000/5000 supports voice compression according to the G.729 and G723.1 standards.
G.723.1 facilitates the use of teleworking via ISDN for example, and reduces the load on the
existing data network. G.723.1 reduces the VoIP bandwidth requirement for voice communica-
tion. This enables a bidirectional voice connection via an ISDN B channel. This, in turn, facili-
tates the connection of teleworkstations or branch offices to the company network via a 64 KB
connection. However, it is not advisable to operate other applications (such as Application
Sharing, File Transfer) in addition to a bidirectional VoIP connection simultaneously via 64
Kbps since this generally leads to a deterioration in voice quality. It is recommended that both
B channels of an S0 connection are used for this purpose.
The HG 1500 supports codecs for compression and decompression of voice signals in accor-
dance with industry standards G.711 A-law, G.711 µ-law, G.723, G.729A and G.729AB. The
codecs can be arranged according to their priority. The gateway automatically attempts to use
a codec with the highest possible priority for each connection.
The HG 1500 supports the following codecs:
G.711 (A-law and µ-law) voice coding – an ITU (International Telecommunication Union)
●
standard for voice coding at 56 or 64 Kbps
G.723.1 voice compression – an ITU standard for voice coding at 5.3 or 6.4 Kbps
●
G.729A and G.729AB voice compression – an ITU standard for voice coding at 8 Kbps
●
13.6.4.3

DTMF Handling

DTMF (Dual-Tone Multifrequency) is the type of audio signal used for tone dialing in accor-
dance with ITU-T standard Q.24. It can be used for call setup and for signaling during a call.
HG 1500 supports the detection and processing of DTMF (Dual Tone Multi Frequency) signals
in accordance with Q.24 regarding signaling for VoIP calls. In particular, it supports the follow-
ing functions:
Detection of DTMF signals
●
Conversion of DTMF signals into user input signals in accordance with H.245
●
Generation of DTMF signals for PSTN
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Speech protection using Bellcore test tapes
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13.6.4.4

Voice Quality

Various HG 1500 functions ensure optimum voice quality during VoIP connections. Further de-
tails are described below.
13-22
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A31003-H3590-S100-7-7620, 06/2012
HiPath 3000/5000 V9, Service documentation