T-Comfort Comfort Pro S, Mounting And Commissioning Manual

Page: 100 / 200

98
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 half-duplex ethernet; for full-duplex the values can be halved.
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
3 Satisfactory GSM
4 Limited Defective GSM
> 4 Unacceptable No Connection