Im working on a Mitel sx200 digital with the analog cabinet. From various rooms you can hear tones from other phones coming over the line but just so they are barely audible. The rooms are not on the same bays or cards. I isolated the problem to the switch. I have tried the ground, and I have removed the surge clamp assemblies. I am left with swapping out the DX mod next. Anything Im forgetting.

Thanks for the help

thinking off the top of my head I would look at Main controller,dx,trunk card maybe dtmf reciever but I am reaching on that one.