02-12-2019 02:54 PM - edited 03-17-2019 02:06 PM
Hi,
I'm trying to get an idea on how to approach troubleshooting one way no audio issue as below.
-Cisco IP phone to PSTN, calls connect but external party cannot hear audio, Cisco Phone can hear external party.
-Internal to Internal calling, no audio issues
-Calls from PSTN to Cisco IP phones, no audio issues.
This was escalated to Telephone Service provider and senior team, but out of interest and keen junior Cisco technician I would like to see proper way to approach and troubleshoot the above issue. From Firewall to Voice Gateway.
Thanks in advance!
Solved! Go to Solution.
02-12-2019 10:14 PM
As a starter you can try below
1) Approach :1 :- Find out Packets sent and received on Phone
===> Here we will make a live test call see the Packet received and sent counters on IP Phone To isolate issue is between Which Subnet to Which Subnet
====> Once Call is active you can view Call Statistics in Phone by settings > Admin Settings >Status>Call Statistices on 7800 Model or Press ? button twice on 7900 Models
2) Check if required Ports are open in the path were you are facing issue i,e RTP Ports 16384 - 32767 UDP. Check the ACLs, Routing , Firewall Rules
3) Check if SIP/SCCP Inspection is disabled in firewall. Also check if path involved any NAT.
Thanks,
Haris
** Please rate and mark solution accepted if applicable.
02-12-2019 03:09 PM
Most of the time one way voice Due to NAT issue, also considering looking at Codec Translation.
02-12-2019 04:44 PM
02-12-2019 10:14 PM
As a starter you can try below
1) Approach :1 :- Find out Packets sent and received on Phone
===> Here we will make a live test call see the Packet received and sent counters on IP Phone To isolate issue is between Which Subnet to Which Subnet
====> Once Call is active you can view Call Statistics in Phone by settings > Admin Settings >Status>Call Statistices on 7800 Model or Press ? button twice on 7900 Models
2) Check if required Ports are open in the path were you are facing issue i,e RTP Ports 16384 - 32767 UDP. Check the ACLs, Routing , Firewall Rules
3) Check if SIP/SCCP Inspection is disabled in firewall. Also check if path involved any NAT.
Thanks,
Haris
** Please rate and mark solution accepted if applicable.
02-13-2019 04:38 AM - edited 02-13-2019 04:41 AM
We have done Wireshark capturing from Cisco IP Phone, no issues were picked up, all looked good.
We have then disabled SIP/SCCP Inspection. Once disabled the one way audio issue was resolved.
Now, is it best practice to leave SIP/SCCP Inspection disabled permanently? are there any issues with leaving it disabled in this case?
Much appreciated with help received!
02-12-2019 11:05 PM
Hello,
You better check on your firewall if SIP inspection is enabled and if it is test by disabling it.
George
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