Aastra OpenCom 130 User Guide - Page 111

Voice Quality, Quality Levels for Voice Transmission with VoIP

Page 111 highlights

Voice over IP (VoIP) Fundamentals The following table provides an overview of the required bandwidth for a telephone connection with various parameter settings. The values apply to halfduplex ethernet; for full-duplex the values can be halved. Required bandwidth (kbit/s) with respect to Packet Length and Codec Packet Length (ms) 20 30 40 50 60 70 80 G.711 (not compressed) 180.8 G.729A G.723.1 approx. 8 kbit 6.3 kbit/s /s 68.8 51.2 48.0 42.4 37.12 33.6 30.4 31.09 29.2 G.723.1 5.3 kbit/s 45.9 28.3 You will require a licence with which you can activate the G.729 codec for operation (in the System: Licences menu). Note: To ensure SIP compatibility, the older system telephones OpenPhone 63 IP and OpenPhone 65 IP do not support the G.723 codec any more. 9.2.3 Voice Quality The achievable voice quality depends on various factors. It is possible to optimise voice-data transmission on an existing network using the available configuration settings. Measuring the network quality may also help. The following comparison provides a guide to voice quality with specific quality levels: Quality Levels for Voice Transmission with VoIP Level Voice Comprehensibility 1 Very Good Comparable to ISDN 2 Good DECT 109

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Voice over IP (VoIP)
Fundamentals
109
The following table provides an overview of the required bandwidth for a tele-
phone connection with various parameter settings. The values apply to half-
duplex ethernet; for full-duplex the values can be halved.
You will require a licence with which you can activate the G.729 codec for oper-
ation (in the
System
:
Licences
menu).
Note:
To ensure SIP compatibility, the older system tele-
phones OpenPhone 63 IP and OpenPhone 65 IP do not sup-
port the G.723 codec any more.
9.2.3
Voice Quality
The achievable voice quality depends on various factors. It is possible to optimise
voice-data transmission on an existing network using the available configuration
settings. Measuring the network quality may also help. The following comparison
provides a guide to voice quality with specific quality levels:
Required bandwidth (kbit/s) with respect to Packet Length and Codec
Packet
Length (ms)
G.711 (not
compressed)
G.729A
approx. 8 kbit
/s
G.723.1
6.3 kbit/s
G.723.1
5.3 kbit/s
20
180.8
68.8
30
51.2
48.0
45.9
40
42.4
50
37.12
60
33.6
30.4
28.3
70
31.09
80
29.2
Quality Levels for Voice Transmission with VoIP
Level
Voice Comprehensibility
Comparable to
1
Very Good
ISDN
2
Good
DECT