Network Audio Quality Display on 4600 Series IP Telephones

As of Release 1.7 for the 4620 and 4630/4630SW telephones, and as of Release 1.8 for the other 4600 Series IP Telephones, the telephone is by default administered to offer the end user an opportunity to monitor network audio performance while on a call. The user guides for each phone go into specific detail on how the user gets to the appropriate screen; this document tells you what the end user can see, and what it means.

For 4610SW/4620/4620SW/4630/4630SW IP Telephones, the following parameters are displayed in real-time to users on the appropriate screens, while on a call:

Table 4-4. Parameters in Real-Time
Parameter	Possible Values
Audio Connection Present?	*Yes* (if a receive RTP stream has been established) No (if a receive RTP stream has not been established)
Received Audio Coding	*G.711* or *G.729*
Silence Suppression	*Yes* (if the telephone knows the far-end has silence suppression Enabled) No (if the telephone knows the far-end has silence suppression Disabled, or the telephone does not know either way)
Packet Loss	No data or a decimal percentage. Late and out-of-sequence packets are counted as lost if they are discarded. Packets are not counted as lost until a subsequent packet is received and the loss confirmed by the RTP sequence number.
Packetization Delay	No data or an integer number of milliseconds. The number reflects the amount of delay in received audio packets, and includes any look-ahead delay associated with the codec.
One-way Network Delay	No data or an integer number of milliseconds. The number is one-half the value RTCP computes for the round-trip delay.
Network Jitter Compensation Delay	No data or an integer number of milliseconds reporting the average delay introduced by the telephone’s jitter buffer.

For 4602/4602SW/4606/4612/4624 IP Telephones, the Network Audio Quality Screen presents the user with a qualitative assessment of the overall audio quality currently being experienced. This assessment is based on separate evaluations of the Packet Loss and the total Network Delay (the sum of Packetization Delay, One-way Network Delay, and Network Jitter Compensation Delay), and consideration of the codec in use. You can disable the display of the Network Audio Quality data and assessment for all sets by setting the system value NTWKAUDIO to a value of “0” as explained in Administering Options for the 4600 Series IP Telephones.

The implication of this information for LAN administration depends, of course, on the values reported by the user and the specific nature of your LAN (topology, loading, QoS administration, etc.). The major use for this information is to give the user an idea of how network conditions are affecting the audio quality of the current call. It is assumed you have more detailed tools available for troubleshooting the LAN.