When I plug my PC into Polycom phones and try to analyze the data from the phones I'm not able to see any data. No RTP stream, no Voip calls, nothing. When I plug my computer into a Cisco phone and analyze the data everything shows up perfectly, just not with the Soundpoint IP 430 and 330 Polycom phones we use. Cisco has an option called "span to PC port" but it doesn't appear Polycom phones have that same option so I'm not sure why it's not working. Thanks
asked 26 Jul '12, 16:42
That's the reason why you don't see anything when your PC is hooked to the Polcyom.
VoIP Packets come in on the [LAN/NET] port of the Poloycom. If the phone does not copy those packets to the [PC] port, there is no way to capture the VoIP traffic on the attached PC. Cisco's option "span to PC port" does exactly that.
If Polycom does not have such an option, you can only capture on a mirror/span/monitor port of the switch.
There is a nice animated explanation of Port mirroring on the following website. At the bottom: "How Port Mirroring function is used for VoIP call recording" (requires flash).