I have a door itercom device from Viking Electronics that is connected to a FXS/stcapp port on my CME. When visitors hit the "call" button they get tone from the CME and can dial an extension to be buzzed in. I would like to have the intercom autodial an extension when the intercom goes offhook without having the visitor dial anything. Something like "plar opx" but it seems that "plar opx" is only for FXO ports. What is an equivalnet for FXS ports?