the cisco page you link to more accurately describes fxo disconnect, especially on more recent devices like voip pbx gear but one of things with battery reversal, particularly in modern telephony is that implementations will vary, the calling party control thing is right with regards to the FCC which means that the polarity on an FXS line shouldn't matter so when a battery gets revered, as far as it being a call control signal, it basically gets ignored and the port remains busy. This is typical but not not necessarily "correct" behavior.
was there a particular piece of equipment or a specific issue you're having that this is in regards to?
