I know there a term for it, I cant remember what its called, but I've got an issue on my Avaya ACS 6.0, may only seem worse because its in a mechanics shop, but they are having an extremely hard time hearing customers, because when they turn the volume up on the handset, the return sound form the mic that comes back through the earpiece so you hear yourself a bit is MUCH louder than the person on the other end. So they are basically hearing themselves in the earpiece nearly louder than the person they are talking to. Now I know this is more an issue with the analog POTS line coming in, but where do I go from here to try and remedy this? Telco had already been out, and tested the lines, said they were fine, so I'm kinda left at a blank. Thanks in advance for your time!