A.Echo is the discernable leak-through of your own Rx path into your own Tx path. 
B.Echo is the discernable leak-through of the packets of your Rx path into your own Tx path. 
C.Echo is the nonaudible leak-through of the packets of your Rx path into your own Tx path. 
D.Echo is the audible leak-through of the packets from the transmit path into your own receive path. 
E.Echo is the nonaudible leak-through of the packets of your Tx path into your own Rx path.

A.The gain functionality applies to outbound audio packets. Distortion is created when an external participant causes echo. 
B.The distortion is unrelated to the gain functionality. Rather, it is a result of the company trying to maintain too many conference calls at one time. 
C.This functionality cannot discriminate between a local VoIP source that requires volume gain and a CO-powered PSTN source that does not require volume gain. 
D.This functionality cannot discriminate between a remote VoIP or Foreign Exchange Office source that requires volume gain, and a remote VoIP or IP phone that does not require volume gain.