ISDN Software Reference for Linux and Windows
338
External Event Indicates:
in response to a cc_SndMsg( ) function call,
from the far end, in which the msg_type is
SndMsg_UsrInformation.
Use the cc_GetCallInfo( ) function to
retrieve the UUI.
7.2. Error Handling
The ISDN library functions return a value indicating success (0) or failure (<0) of
the function call. cc_CauseValue( ) is used to retrieve the reason for the failure.
The application may use the cc_ResultMsg( ) function to interpret the returned
value.
ISDN error/cause codes consist of two parts: error location and reason. The error
location is the upper byte and the reason is the lower byte. For example, the error
code (ERR_ISDN_FW | ISDN_CHRST_ERR) indicates that the error is located
in the firmware and the reason for the failure is a channel restart error.