So I have replaced some Samsung 3 line sets with a CICS and 7 t7316e sets. Now the customer and I noticed that talking on any analog line causes an echo. You can hear your self talking through the phone. I replaced the CICS and the line cards but this fixed nothing. Is it a bad batch of t7316e's? I don't get the echo on intrernal calls but I get it on all 4 of the analog lines. Thes lines are standard analog lines, there is now VoIP or digital conversions over the line. Changing the line settings to shortCO or longCO has changed nothing. I can't find the problem. Could it be a grounding issue? I'm at a loss