Aastra OpenCom 130 User Guide - Page 111
Voice Quality, Quality Levels for Voice Transmission with VoIP
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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