Ok, so I'm clueless to the inner workings of this phone system. I've inherited this, and its taking me awhile to get up to speed as I have zero past experience. I have an extension that works fine except the handset will not work. I can use speakerphone all day long. I swapped out phones as a standard "IT" troubleshooting step, but the same results with any phone I connect to that line. Does anyone have any ideas on how to resolve this issue?