Getting packet captures for IP Phone

[sagar.sarker]

Hi,

I want to take captures for IP phone calls to  find out the frequency and cadence of the FXO ports. My county doesn't  have listed cptones.

Now while i'm trying to get the  captures, i am not getting any UDP stream from source IP (which is  usually the gateway IP address) to IP phone. Its only the skinny  packets. Can anyone help me to get appropiate captures.

For your information, we are using 8 PSTN lines connected to the FXO ports of the router.

Regards,

Sagar

[espereir]

Do you have VAD enabled on the dial-peers? if it is enabled, you should disable it, otherwise, it looks like a routing issue since the IP Phone should get the UDPs, have you checked the call statistics screen on the IP Phone (hit the ? button twice), you shoud see incoming packets increasing, if not, you better check the VAD settings and the routing .

HTH

--espereir

[sagar.sarker]

Hi Esperier,

Thanks for your mail.

To my understanding, we can use VAD only on voip dial-peers. We have 8 PSTN lines connected to the FXO ports. On the POTS dial-peer, there is no option for VAD.

Another thing is, we have separate routers for Internet & Voice traffic. Not sure what did you mean by routing issue. We don't have any explicit routing other than the default routing. We have subinterfaced g0/0 into data and voice vlan and the default route is directed to data vlan gateway. Still I'm getting only the TCP & Skinny packets.

Please help me.

Regards,

Sagar

[sagar.sarker]

Hi Esperier,

Can anyone give me some suggestion on how to capture packets through wireshark. I am a bit confused about the procedure I am follwoing. I need advise from someone who really got some experience on this.

Regards,

Sagar

[clileikis]

Hi Sagar,

Check out the following doc regarding capturing packets on 79XX Phones:

https://supportforums.cisco.com/docs/DOC-11735

Thanks,

Chris