One way Voice Issue

[shahulhameed]

Dears,

The users are facing a one-way voice issue only on the first call. There is no issue for the second time, and this is annoying for the users. We have two networks: the SDA network and the non-SDA network. The issue is calls between those networks and between non-SDA network IP phones. There is no problem with SDA network phones. The non-SDA network IP phones are all registered with the same subscriber. The access switch model is 4500, and the IOS version is 03.09.00E. I doubted the IOS may cause the issue, but I am not sure.

I have opened a case with Cisco, but they cannot find the issue without logs. I have tried many ways to collect the logs (I installed Wireshark on a few laptops and tried to collect them from the switch), but all times I failed because the issue is not permanent and not happening for all users. I am posting here because sometimes you guys may face the same issue and resolve it with very simple changes.

Please advise.

[Carlo Poggiarelli]

Hi @shahulhameed 

Well we can look into CUCM Trace Logs if you have a specific time when the issue happened. Sometimes it depends on an MTP source not correctly allocated which means than the RTP  path goes directly between the call parties.

If you can attach the trace logs, and specify the correct time, would help us to dig into the log.

Thanks

Regards

Carlo

[shahulhameed]

Hi @Carlo Poggiarelli 

Thanks for your immediate response. As I said earlier, we were not able to find anything in the RTMT trace logs. Please see the Cisco reply below.

I am trying to collect full traffic logs between both devices, but unfortunately, I couldn't. MTP is not enabled for the phone. We have the issue internally, so as per Cisco's advice, it is disbalanced.

[Carlo Poggiarelli]

Hi,

I understand that you didn’t find nothing relevant on Trace logs but this, on my experience, could be a starting point to dig into an issue.

Just a couple of questions:

What do you mean with “First Call”? The first call of the day or after a period of inactivity?

Is the one way audio issue occurring for pstn or interal calls or both?

Please let me know.

Regards

Carlo

[shahulhameed]

Hello Carlo,

Please find below the answers to the questions.

First call means, for example, that when user A is trying to call user B for the first time, either user A or user B is not able to hear the other voice. There will be no issue remaining after it, but sometimes it rarely happens after some time. Sometimes no issue happens at all after a first-call failure. But it is happening for other users.

The audio issue is happening internally as well as on PSTN. But as I said earlier, the issue is happening for the non-SDA network, which contains most probably 4500 series switches. There is no issue with the SDA network, which has 9300 series switches.

[Carlo Poggiarelli]

Hi,

Did you apply any QoS template on Phone ports on Non-SDA network? If not try to enable auto qos on access ports and QoS trust on trunk ones. also… Are Calling and Called User on the same Subnet/VLAN?

Thanks

Regards

Carlo

[shahulhameed]

Hi,

QoS is not configured. Let me try and update to you.

Regards,

[shahulhameed · Accepted solution]

Hello Friends,

The issue is because of the symmetric routing problem. Also, the CPU utilization was high. After fixing these two, the one-way voice issue has been resolved.

[Maren Mahoney]

Thank you for sharing your solution for those who search on this topic later! -- Marne