No audio issue - Cisco IP phone 7821/3905

[Vinod.s]

Hello Team,

We are facing no audio issue in 7-8 CP-7821/3905 phones and after rebooting its working fine .

I am following this doc : https://community.cisco.com/t5/collaboration-voice-and-video/how-to-troubleshoot-one-way-no-audio-issues/ta-p/3164442

According to this doc :-> 'Local' and 'Remote' IP addresses, then you see the port, if the information is the same on the other side, ('Local' on one side should correspond to the 'Remote' on the other), then signalling is good.

Means : 10.10.10.10(Remote)/ 22033 10.10.10.11(Local)/ 23056

10.10.10.11(Remote)/23056 10.10.10.10(Local)/22033

But in my case ports are different on other side .

10.10.10.10(R)/ 22033 10.10.10.11(L) / 23056

10.10.10.11(R)/24356 10.10.10.10(L)/23233

My question is - if port is different then it will cause no audio issue ? 

If Yes, then how i can mitigate this ?

Can anyone help on this .

[Aswin S]

I am not sure about change in port numbers but if you provide debug ccsip message log of a sample call it will be helpful to narrow down the issue.

[Vinod.s]

I guess this command needs to run on gateway but i am facing issue in internal extension .
No pstn call issue observed.

[Maren Mahoney]

The IPs you are using imply that the two phones are on the same subnet. If you have sanitized the IPs and the phones are not on the same subnet, can you describe the architecture?

If the two phones are not traversing a CUBE/SBC and are instead signaling through CUCM, is an MTP in play?

It might be worthwhile to you to download the trace that includes the call and dump it into TranslatorX to follow the signaling path showing the SDP negotiation of the ports.

Maren

[Vinod.s]

Hi Maren,

Call flow : Ipphone - cucm - ipphone.
Obviously there is firewall in picture since cucm placed in restricted vlan.
Both phones are same model and subnet , vlan is same still mtp will play role ?

After restarting this working fine and after 1-2 days again issues started.
I am concreting on sdl logs only but i dont know which parameter should i checked to confirm its firewall issue or firmware issue .

[Maren Mahoney]

Restarting the phones or restarting CUCM solved the issue for a day or two? (That is interesting.)

The change in port numbers would normally make me think the firewall is doing NAT or interfering in some other way, but the fact that the problem occurs only after a couple of days implies this is not the case.

Is it just these two phones? Do other phones experience this? Is the firewall voice-aware?

What you'd be looking for in the SDL files is an analysis of the SDP exchange in the SIP messages to show port negotiation (on the m= line) and compare that to the logs on the phones who are receiving those messages. Check the in and out to both phones.

If what the CUCM sends and what the phones receive is different, then the firewall is the culprit. If what the CUCM sends and what the phones receive is the same, then I'll have to think about that a bit.

Maren

[Vinod.s]

Restarting a phone solve an issue. We are not restarting a cucm .