Doubt about one-way audio issues

[wilsonsant]

Hi Guys,

My Customer is having problem with few calls (in alleatory extension or directory number) where the side on company the User don´t hear another side. Question: what logs is more recommended to collect then to analyze this issues?. I collected the logs CallManager about RTMT, but, not is possible to be conclusive.

Thanks,

Regards,

Wilson

[mmoulson1]

Is it totally random? Or is it always the same behavior?

E.g. DN 1000 can always call DN 1001 without any problems, but it DN 1000 tries to call DN 1003 the problem is always experienced?

[wilsonsant]

Hi Mmoulsom1,

Thanks a lot for Your contact. This is a problem randomly, the most call work fine and occur only to external calls (in and out)

Thank You,

Best Regards,

Wilson

[mmoulson1]

What devices do you have in the path? What are you using for a gateway? Is it ISDN? SIP etc?

[wilsonsant]

Hi Mmoulson1,

I don´t have access the full topology, but, I know that there switch, firewalls in the path. We are using SIP.

Thanks,

Regards,

Wilson

[mmoulson1]

You need to understand the full topology to be able to figure out what devices could be causing you issue.

If you are passing SIP through the firewall then in my experiance this can cause issues is as some firewall will handle the process better than others. Depending on the firewall brand SIP ALG, Fixup SIP, Inspect SIP are all processes that the firewall maybe doing to try and pass the SIP traffic from the inside to the outside of the network. The firewall will try to modify the SIP header information to ensure the source and desination IP addressing is correct. If your ITSP recieves SIP messages that contain private addressing they won't be able to reply to you so the firewall handles this process. Again call volume and the capability of the firewall can play a part in why you get some calls working OK and others where you have one way audio.

Hope that helps!

Matty

[wilsonsant]

Hi mmoulson1, 

Thanks a lot for Your return. Answering Your question, yes, the SIP pass throught, but, I don´t have full know and access about the topology, because, my access is restricted only CUCM, Gateway and Switch. I agree with You, this problem can be related with Firewal.

Thanks,

Regards,

Wilson

[Sam V. Xavier]

Hi Wilson,

99% of the cases for one way audio are routing related, that is, packets not reaching from source (IP Phone or gateway) to the destination (IP Phone or gateway). Thus to further isolate the issue packet capture would be more beneficial than logs from CUCM. Also you would want to check the route by pinging and I am sure you would see drops after a certain point.

Regards.

[wilsonsant]

Hi Sam V. Xavier, 

Thanks a lot for Your contact and Your explanation. I will try to do capture packet as that You indicated.

Regards,

Wilson

[Dennis Mink]

In addition to this, I always use the SDP in the SIP traces to see what the IP address is the RTP is negotiated to be terminated on, so I can establish if a. routing works and b, if there is a potential blocking fw in the path.

[wilsonsant]

Hi Dennis,

Thanks a lot for Your contact. The problem was verified only one in a call did by Director. Don´t have more problem about this, but, if the problem occurr again I will to follow Your suggestion.

Thanks,

Regards,

Wilson

[GrumbleShark]

Most of the time one way audio is routing related.  One a 7900 series phone you'd hit the ? twice to bring up the call statistics, on 8800 series phones I believe that it's in the administrative settings (don't quote me on that).  You'll likely see one phone receiving 0 packets.  You could also look in the CMR files with a tool like Solarwinds CDR tool or VoIP Detective.

[wilsonsant]

Hi Terry, Thanks a lot for Your contact. Answering Your questions:

> In the environment don´t have 7900 IP Phones series

> The IP Phone that had problem is 8851, but, I don´t believe that the still be possible to collect the logs in this Phone, because, the problem occurred one week ago

> About the Tools, I to see both and appeared interesting, but, I don´t believe that the Company want purchase (Telephony not is bussiness of the Company)

Thanks,

Regards,

Wilson