Observer Analyzer : Observer Analyzer : VoIP and Teleconferencing : Analyzing VoIP or video conferencing traffic
Analyzing VoIP or video conferencing traffic
Observer constantly monitors network conditions to calculate the R-factor, and allows you to customize the non-network impairment factors such as room noise, loudness rating of the telephone, etc.
Prerequisite(s):  
Either start a packet capture or import a capture file.
 
Analyzing VoIP traffic follows the same rules and behaviors as when analyzing any packet capture; you can analyze the packets in either real-time or post-capture modes. Real-time mode is simply analyzing packets as they arrive (i.e. the packet capture is currently running), while post-capture is analyzing packets from inside a saved packet capture file at a later time. This section describes both real-time and post-capture VoIP analysis.
Tip! You cannot create a pre-filter that filters for a specific phone number. However, you can select Find in VoIP ID stream from a right-click search through the VoIP Events / Calls tab based on a phone number. After you find the conversation in question, right-click it and select the Fast Post Filter option to filter out the particular VoIP call.
You can learn more about decoding/analyzing network traffic by seeing Decoding network traffic—a wealth of information is provided there should you need it.
To analyze VoIP traffic, begin by starting a packet capture or loading a saved capture file. If necessary, see the instructions for doing so at Capturing network traffic.
1. On the Home tab, in the Capture group, click Configuration > Packet Capture.
2. Click the Decode button.
3. Ensure the Expert Analysis tab is selected.
 
Figure 53: Expert Analysis tab location
 
4. Click the VoIP Events group tab.
5. Click the VoIP Settings button to view or change VoIP-specific settings.
These settings are shared with the settings described in Configuring network trending settings for VoIP or video conferencing.
6. Click the Expert Threshold button to view or change settings that determine VoIP-specific decode settings.
 
By using MOS score and R-factor when looking at your VoIP environment, you can determine if your users are experiencing poor call quality. From the VoIP Events group tab, you can perform meaningful decoding of VoIP packets, including the ability to see call statistics as they arrive.
 
 
The Table 23 lists the abbreviations used in the VoIP Events tab for various packet types.
Table 23. VoIP Events tab abbreviations
A
Audio
C
Control
D
Data codec (non-audio or video data)
Q
Quality for RTP Packets (always RTCP)
V
Video