Able to hear voice only one-way within Extensions

[ravindupriyankara96]

Hello Folks,

After went through multiple disscussions figured out this is a kind of common issue but with diffferent solution for each.

Since i didn't found proper solution for me starting this discussion. 

Issue is quite simple,

We have spoc location and CUCM connectivity enabled over tunnel to singapore. and all was worked fine till we had a down incident with primary CUCM server. Now all back to normal and we`re facing voice hearing issue only one way.

External calls working fine issue is within internal extension and all phones are connected with same vlan/subnet

Lets continue with discussion will provide more details

[Roger Kallberg]

A power outage for a CM would not have any impact on what you seeing. Without a doubt this is not the cause of your problem.

One way audio is caused by the media (RTP) stream not successfully going between the endpoints in the call. Only if you were to have some odd setup with a media termination point (MTP) involved in the call would the media not flow directly between the endpoints in the call. If the devices truly are on the same subnet and you don’t have anything blocking the RTP stream it would be quite unlikely that you would have one way audio. What do you see on the endpoints in the call if you look at the statistics on each of them? Do they show both received and sent packets? If not there is something blocking the stream from flowing between the endpoints.

[eyalraba]

In addition to what Roger mentioned, issue can happen also if the SIP ACK message has not received one of the parties. You can attach phone console logs from both phones and Cisco Call Manager logs, we can check them to confirm the signaling is ok.

[ravindupriyankara96]

sorry for late reply, after 4th bridge call still facing the issue we have B site also registered in same CUCM extension to extension from A site to B working perfectly. only facing issue within site A. I believe CUCM/TELECOM out of scope here.   

[Scott Leport]

What do you mean by "down incident"? Did the incident affect only the primary CUCM or other parts of the network?

Is the one-way audio issue only present within a single site with internal calls or is it on-net calls between the phones registered to the primary CUCM server and other locations?

One way audio is usually related to IP connectivity issues, such as routing, NAT or firewalls not allowing specified RTP ports through. If the issue is truly single site and phones within the same subnet are impacted it could be something CUCM side, but might be a super specific issue that you would need TAC assistance on.

[ravindupriyankara96]

We have few sites connected with this CUCM, but this issue is with only single site and within same subnet. can be this with ios issue?

[Scott Leport]

If by IOS you mean IP phone firmware, difficult to say for sure. But you would need to really drill down into the issue and try and narrow it down to make sense of it. Narrowing it down to specific things such as phones running on certain firmware versions, phones connected to certain switches in certain parts of the site, phones registered to a specified CUCM node in your cluster, to name a few suggestions. Do the two phones in the same site have IP connectivity to each other? 

Roger's original advice in his post stands. You need to make a call between two phones at the affected site and look at the RTP statistics between the two endpoints. Ensure the two IP addresses are the IP phones and not the CUCM. In the statistics, look for sender & receiver packets and these should be incrementing. 

[Roger Kallberg]

If you want help please share the asked for information. Without any further detailed information we cannot help you.