I have CUCM 10.5 with Cisco 7821 and 7945 endpoints. Internal calls are fine. However, I get voice quality issue with outbound calls from Cisco 7821 endpoint. The lost packet rate is always about 2 % with just Cisco 7821 series. Meanwhile, I don't get any lost packets with Cisco 7945 endpoints in same outbound calls. My attached files are call statistics of them.
I also try to test by moving the Cisco 7821 the closest with the voice gateway ( same switch). But, there is still lost packets.
Any ideas for me?
If you have already tested with the latest firmware of 7821 then you may need PCM capture from the gateway to check which side is causing the issue.
Do you doubt lost packet from PSTN side? Follow your link, I will capture the call in my voice gateway. Then what will I do next?
You can either open a TAC case to get them analyzed or you can try an alternate method described below