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Ermir Morina

One Way audio from Remote Phone

Greetings Community!


I am having an issue with one-way audio from our remote office Phone to our HQ, so the problem is that on calls (inbound, outbound) we get no audio from the Phone that resides on one of our remote offices (meanwhile other offices work just fine with the same setup).

We have the CUCM v11.0 (Publisher & Subscriber) which is reached by phones through DMVPNs configured on Cisco ISR4331 (CUBE), the phone that I am testing on that remote office is a 7811.

I tried gathering logs from calls and I can see no issue from what I could read and understand, also tested routing from HQ to that office and vice versa and everything seemed just fine.

Could you please give me any hint, tips or any ideas how to troubleshoot and maybe solve this issue that I'm facing?


Looking forward to your replies and discussion.


With much respect, 


Steve Landon



Is this a new site? Has it worked before?


There are a number of possible causes for this symptom. Most often, in my experience, it is a routing issue.


I would ensure that the device you are testing with has a route back to the endpoint you are testing from.


If there is a route and you have eliminated that as an issue, it might be helpful if you described (or have a drawing of) the call path for a working call vs a non working call.



Nithin Eluvathingal
VIP Mentor

Most common cause on one way issues is routing. Do a ping from remote location phone subnet to HQ phone subnet(both direction).



Response Signature

Scott Leport


As others have said, it can typically be a routing issue, but it can also be NAT or Firewall rule related too, specifically if any Firewalls in the path are not allowing the RTP port range required. Best to check on that too.


While troubleshooting the issue, you can make a live call and if the phone has web access enabled, click on the IP address of the registered IP phone in CUCM and check the streaming statistics or if the phone is local double tap the "?" key and that will tell you which IPs are being used to send and receive RTP and check on the counters for packets sent and received.

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