I recently changed from a 3725 w/nm-hdv/wic-1mft-t1 to a 2821 w/vwic2-2mft-t1e1. I had default voice-port settings no the 3725 with no report of echo for 2-years. After moving to the 2821, I am getting numerous reports of echo to/from the PSTN on the side of the IP phone user.
I have a TAC case, and have verified no slips on the controller, and have played with the input gain and output attenuation. For now, those are at -4,4, and I'm still getting echo.
My TAC engineer has now asked that I capture calls on the gateway, which I am working on doing.
The question is, should I try anything else, or is there anything else that I can do to troubleshoot other than playing with the in/out gain?
I have attached a show tech.