4.8.  gc_DropCall( )

The gc_DropCall( ) function supports the following values for its cause parameter:

• GC_CALL_REJECTED: call is not accepted
• GC_NETWORK_CONGESTION: cannot establish connection due to volume of traffic on network
• GC_NORMAL_CLEARING: normal end of call
• GC_SEND_SIT: sends a special information tone
• GC_UNASSIGNED_NUMBER: invalid called party number
• GC_USER_BUSY: called party is busy

CAUTION

You must use the dx_stopch( ) function to terminate any application-initiated voice functions, such as dx_play( ) or dx_record( ), before calling gc_DropCall( ).

Some protocols do not support all gc_DropCall( ) causes for dropping a call. Any unsupported cause(s) is automatically mapped to the most appropriate cause. This approach facilitates developing protocol independent applications.

From the Accepted state, some protocols do not support a forced release of the line; that is, issuing a gc_DropCall( ) function after a gc_AcceptCall( ) function. Refer to the Protocol Limitations section in the Global Call Country Dependent Parameters (CDP) Reference for your protocol. If a forced release is attempted, the function fails and an error is returned. To recover, the application should issue a gc_AnswerCall( ) function followed by gc_DropCall( ) and gc_ReleaseCall( ) functions. However, anytime a GCEV_DISCONNECTED event is received in the Accepted state, the gc_DropCall( ) function can be issued.

After the gc_AnswerCall( ) function is issued, the application must wait for a GCEV_ANSWER event. Otherwise the gc_DropCall( ) function is ignored, no error is returned, and no drop call action is taken.

When using ICAPI protocols (Springware only), the gc_DropCall( ) function occasionally results in the generation of the GCEV_DROPCALL event followed by a GCEV_BLOCKED event. The generation of the GCEV_BLOCKED event is most likely if the gc_DropCall( ) function is issued before the call is connected. The reason for the GCEV_BLOCKED event is that the remote side does not recognize the disconnection in a timely manner. When the GCEV_BLOCKED event occurs, call-related Global Call functions should not be issued until a GCEV_UNBLOCKED event is detected on the respective device.

In some protocols, a gc_DropCall( ) command on a call in the Accepted state requires a momentary transition to the Connected state. This may result in a charge being registered for the call.

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