Ok, So I am trying to still figure out my ringing issues. This time I grabbed the butt set I own and hooked it into my pots line. With the butt set in monitor mode, I called the pots line so I could actual hear the AC ring. It was a low frequency ringing sound like I am accustomed to. I then hooked same butt set to the TDM and initiated ringing from a SIP extension. I heard the data for the caller ID come across then I heard a much higher pitched ringing sound. Almost like, even though the TDM setup has been verified at 20 HZ, it is ringing at a much higher frequency. Any ideas?? If someone wants, I will try and do a recording of both sounds so you can hear for yourself.. Robert