We are having a problem where a speaker can hear their own echo during a call. The person they are talking to does not hear the echo. Sometimes, it may affect the quality of the voice of the person they called, as well. I ran a wireshark and determined that the echo is coming from the PBX side (it doesn't appear in the recording from the phone side). Acccording to the wireshark, the correct G711 codec is being used (I mention this as other threads have suggested the problem is caused by the wrong codecs). I have tried to both check and uncheck 'PBX delivers audio' at the affected extension to no avail. The VoIP Provider is checked as 'PBX delivers audio'. Would anyone have any suggestions on where to look next?