Problem in TAPI 3.0 (hanging up the call during the call transfers to voice mail)

[Radiance Udai]

TapiClass tobj=new TapiClass();
BasicCallControl bcc;

When we try to Disconnect the call,if the call state is in
"callConnecting" especially during the call is switched to voice
mail, the following two lines are causing problem and crashes the
application.

Here is the code which causes the application hangs -up.

bcc.Disconnect(DISCONNECT_CODE.DC_NORMAL);
tobj.Shutdown();


Below is the code snippet responsible for Disconnecting the call.

IEnumCall ec = ia[line].EnumerateCalls();
uint arg = 0;
ITCallInfo ici;
try
{
ec.Next(1,out ici,ref arg);
ITBasicCallControl
bcc=(ITBasicCallControl)ici;
bcc.Disconnect(DISCONNECT_CODE.DC_NORMAL);
tobj.Shutdown();

}

let me know if anybody knows the solution