TAPI : Detecting disconnected Message

Hello,

I am using a US Robotics modem for developing a TAPI Application. I am unable to detect the Disconnected message(LINECALLSTATE_DISCONNECTED) using the
modem whenever the caller drops the line. How can I detect it ?

Thanks in advance,
Partha

If you are behind a PBX and the PBX not work very good ,that is to say it's frequence is same as anonther "MESSAGE" such as LINECALLSTATE_DISCONNECTED,,,
you will be unable to detect the Disconnected message(LINECALLSTATE_DISCONNECTED) using the
modem

thanx for ur reply. I am using EPABX for the line. But I checked with the outside line also and still was unable to detect. So what will be the
solution to overcome this problem ?