Step1. Install Wireshark
Step2. Run the application after installation.
Step3. Click the option Edit→Preference of Menu Bar, and you can get the followed picture: Click the Capture,then choose your network card in the Default interface then confirm.
Step4. Close the application and you can catch packet after restart.
Step5. Configured the filter condition
For example，if you want to filter one of the IP Phone, you could filter its’ IP Address. the format is ip.addr==192.168.3.38, and if you want to filter the SIP packet, you should put sip or ip.addr==192.168.3.38&&sip — catch the SIP packet by x.x.x.x IP address. And if you want to catch two or more IP Phone’s packet, you could fill
ip.addr==x.x.x.x IP Address||ip.addr==x.x.x.x IP address||ip.addr==….
Step6. After fill in the condition which you want to filter, click Apply, and then click a new live capture（）.
Step7. Choose the “Display” in the pop-up the dialog box when saving, and then confirm.
NOTE: You could send us the packet which you have captured and we will analyze it.
Partially understood.... can you show us how to analyze the captured packets....