I have a Canon MP780 all in one (printer/scanner/fax/copy) connected to an iMac via a USB cable. One telephone line cable goes from the wall to the MP780, and the other from the MP780 to the telephone. Sometimes, when I pick up the phone to make a call, I get no dial tone and the MP780 makes a clicking sound. I have tried using different telephones and it didn't solve the problem. Do you all think the problem is with the telephone line or the MP780?