Hi, I own several DCS 12 phones for my company and I have the owner's manual but it does not seem to instruct you on turning the ringer on and off. I have raised the volume, changed the ringer type, and everything I could possibly think of in order to get one of my units to ring but to no avail. one of the notes address that if the phone does not ring but the light flashes, you have to press the button to pick up the call. This tells me there must be some sort of option to turn it on and off; however this sad excuse for an owner's manual is so inadequate, it doesn't even address this function. Please help me. Thank you, Daniel