Similar issue here although the "not hearing" is only one way. I can hear the person I called but that person cannot hear me. Calls to that number from cell phone and other Xfinity voice users are fine. If that person calls me we can both hear. Noticed a codec mismatch in the modem call logs for those calls that don't work correctly. Power cycling (both modems), rebooting, visit by technician did not solve issue.
Which modem defines the codec? I assume the initiating one but I don't know for sure.
