Voice Quality - Aastra OpenCom 100 Series Mounting And Commissioning User Manual

Voice over IP (VoIP)
Required bandwidth (kbit/s) with respect to Packet Length and Codec
Packet G.711 (not
Length (ms) compressed)
60
70
80
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.

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 set-
tings. 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
2 Good
3 Satisfactory
4 Limited
> 4 Unacceptable
When a call is set up, the terminals involved negotiate the voice-data compression
("codec") that will be used. This is the first factor that determines the achievable
quality level:
112
G.729A G.723.1
approx. 6.3 kbit/s
8 kbit/s
33.6 30.4
31.09
29.2
Comparable to
ISDN
DECT
GSM
Defective GSM
No Connection
G.723.1
5.3 kbit/s
28.3