[Asterisk-Users] Reverse Battery Disconnect Supervision in X100P or TDM400P FXO

[Luis Vazquez]

Is posible to make the Digium FXO cards detect disconnect supervision by 
polarity reversal instead of battery drop??
Our telco carrier here at Uruguay sales two disconnect supervision 
services called Incomming Polarity Reversal and Outgoing Polarity 
Reversal call supervision.
We just bought the first one in the line we are testing with X100P (we 
have bought many TDM400P cards too) but we found the card does not 
disconnect the call when the line polarity is reversed on remote hangup.
We checked with a voltimeter and the line voltage secuence is (approx):
a) +45 : normal state (open circuit)
b) -45 : Just before the first ring
c) -8 : asterisk answer the call (closed circuit)
d) +8 : remote party hangs up (polarity is reversed by telco)
zaptel channel is not hanged up an the call go to timeout, operator 
queue, etc ... PROBLEM HERE
e) +45 : WE finally hang up the channel

Any help will be greatly appreciated.
Luis

Pd: My boss tell me I can spend a week or two in fixing this problem 
through coding in the zaptel driver so if the hardware is capable of 
detecting this, any hint in the proper driver function to look for or 
any reference to the zaptel driver documentation could be of great help.