I have a tapi code. After successfully linedrop, lineDeallocateCall, lineclose, lineshutdown, the next time when I place a call, sometimes I receive LINE_REPLY error message, the param2 shows LINEERR_RESOURCEUNAVAIL, but this is not always happen. But once it happens, I have to try 2-7 times to make a call again. I wait for the LINE_REPLY message after I call linedrop method. Does anybody knows what is missing?