I have a Executone IDS 228, Which is having a problem were the calling party cannot hear the called party, When calling the IC the line is real static.noisy. I have changed the Station Card, which moved this problem from one extension to another extension. I have changed the Processor. I have changed the extension to another extension, changed the telephone, connected the telephone at the system still same problem. Any suggestions. System is about 6 years old. Thanks,