I have a Nortel Opt 11 that is connected to a Cisco UC520. I'm using an NT8D09 to make this connection. My problem is when the nortel analog port is dialed, the Cisco side rings and I can answer. But if there is no one on the cisco to answer and the nortel "hangs up", the cisco does not recognize this disconnect and continues to ring indefinately. Should I be using the nortel nt1r20 opx card? Thanks in advance