Call Rejection

• Outgoing call rejected by the network
• Incoming call rejected by the application
• Glare Condition 1: Call collision occurs after the SETUP message is sent to the network
• Glare Condition 2: Call collision occurs before the SETUP message is sent to the network
• Simultaneous disconnect (any state)

Outgoing call rejected by the network

Synchronous Programming

Application	Device Driver	State	Firmware	Network
cc_MakeCall( ) -->	CRN assigned Call_Outgoing -->	DIALING
			CALL_OUTGOING -->	Set up -->
	CCEV_ DISCONNECTED <--	*DISCONNECTED	CALL_REJECTION <--	Rel_Comp <--
	ISDN_Block_Ts (sync mode only) -->		Incoming call blocked
cc_DropCall( )		IDLE	B channel disconnected CALL_DISC
	CCEV_DROPCALL		CALL_CLEARED <--
cc_ReleaseCall( ) -->	Call_Dealloc -->	NULL
	Driver releases CRN Return <--		F/W releases CRN CALL_DEALLOC_ACK <--
*Application can use cc_ResultValue( ) to determine the cause value for the disconnect (ERR_ISDN_CAUSE).

Incoming call rejected by the application

Synchronous Programming

Application	Device Driver	State	Firmware	Network
cc_WaitCall( ) -->	ISDN_Unblock_Ts -->	NULL	Incoming call unblocked
				Set_Up <--
			*B channel cut-thru CALL_PROCEEDING -->	Proceeding -->
	CRN assigned termination of cc_WaitCall( ) <--	OFFERED	CALL_INCOMING <--
cc_GetDNIS( ) (option) -->
	Return immediately with DNIS <--
cc_DropCall( ) -->	Call_Disconnect (cause value ¹ 0) -->
		IDLE	B channel disconnected CALL_DISC -->	disconnect -->
				Release <--
	termination of cc_DropCall( ) <--		CALL_CLEARED <--	Rel_Comp -->
	ISDN_Block_Ts		Incoming call unblocked
cc_ReleaseCall( ) -->	Returned immediately <-- Call_Dealloc -->
	Driver releases CRN Return <--	NULL	F/W releases CRN CALL_DEALLOC_ACK <--
				Set_Up <--
		OFFERED	CALL_INCOMING <--
cc_GetDNIS( ) (option) -->
cc_CallAck( ) -->				Proceeding -->
*Application may control CALL_PROCEEDING by adding CCMSK_CALL_PROC and using cc_CallAck( ) to send event mask, proceeding toward network.

Asynchronous Programming

Application	Device Driver	State	Firmware	Network
cc_WaitCall( ) -->	ISDN_Unblock_Ts -->	NULL	Incoming call unblocked
				Set_Up <--
			*CALL_PROCEEDING -->	Proceeding -->
	CRN assigned CCEV_OFFERED <--	OFFERED	CALL_INCOMING <--
cc_GetDNIS( ) (option) -->
	Return immediately with DNIS <--
cc_DropCall( ) -->	Call_Disconnect (cause value ¹ 0) -->
		IDLE	B channel disconnected CALL_DISC -->	disconnect -->
				Release <--
	CCEV_DROPCALL <--		CALL_CLEARED <--	Rel_Comp -->
cc_ReleaseCall( ) -->	Call_Dealloc -->
	Driver releases CRN Return <--	NULL	F/W releases CRN CALL_DEALLOC_ACK <--
				Set_Up <--
		OFFERED	CALL_INCOMING <--
cc_GetDNIS( ) (option) -->
cc_CallAck( )				Proceeding -->
* Application may control CALL_PROCEEDING by adding CCMSK_CALL_PROC and using cc_CallAck( ) to send event mask, proceeding toward network.

Glare Condition 1: Call collision occurs after the SETUP message is sent to the network

A glare condition occurs when both an incoming and outgoing call request the same time slot. When glare occurs, the incoming call is assigned the time slot. In this scenario, the firmware detects an incoming SETUP message after transmitting the outgoing SETUP message to the network. In this case, the firmware contains a call reference number for both the incoming and outgoing calls. Therefore, the application must issue cc_DropCall( ) and cc_ReleaseCall( ) to release the outgoing call prior to processing the incoming call. This scenario applies to an exclusive service setting with a firmware-controlled release configuration.

Asynchronous Programming

Application	Device Driver	State	Firmware	Network
cc_MakeCall()-->	Host CRN # 1 assigned Call_Outgoing -->	NULL
			Firmware CRN #1 is assigned CALL_OUTGOING -->	Set up -->
				Set_Up <--
			*B channel cut-thru CALL_PROCEEDING -->	Proceeding -->
	Host CRN # 2 assigned CCEV_OFFERED <--	OFFERED	Firmware CRN #2 is assigned CALL_INCOMING <--
cc_AcceptCall() (option) -->	Call_Alert -->		CALL_ALERT -->	Alerting -->
	CCEV_ACCEPTCALL <--	ACCEPTED	CALL_ALERT_ACK <--
cc_AnswerCall() -->	Call_Connect -->		*B channel cut-thru CALL_CONNECT -->	Connect -->
	CCEV_ANSWERCALL <--	CONNECTED	CALL_CONNECT_ACK <--	Conn_ACK <--
	CCEV_DISCONNECTED <--	**DISCONNECTED	CALL_REJECTION on CRN # 1 <--	Rel_Comp <--
cc_DropCall() -->	Call_Dis -->
CCEV_DROPCALL <--		IDLE	CALL_CLEARED <--
cc_ReleaseCall( )	Call_Dealloc -->	NULL
	Host CRN #1 released		Firmware CRN #1 released CALL_DEALLOC_ACK <--
*Application may connect a voice channel to the B channel. **Application can use cc_ResultValue( ) to determine cause value for disconnect (ERR_ISDN_CAUSE).

Glare Condition 2: Call collision occurs before the SETUP message is sent to the network

A glare condition occurs when both an incoming and outgoing call request the same time slot. When glare occurs, the incoming call is assigned the time slot. In this scenario, the firmware detects an incoming SETUP message prior to transmitting the outgoing SETUP message to the network. The application receives a failure to process the request to transmit the SETUP message (CCEV_TASKFAIL event). In this case, the application does not need to issue cc_DropCall( ) and cc_ReleaseCall( ), and continues to process the incoming call. This scenario applies to an exclusive service setting with a firmware-controlled release configuration.

Asynchronous Programming

Application	Device Driver	State	Firmware	Network
cc_MakeCall()-->	Host CRN # 1 assigned Call_Outgoing -->	NULL
				Set_Up <--
			*B channel cut-thru CALL_PROCEEDING -->	Proceeding -->
ISDN Application does not need cc_DropCall() or cc_ReleaseCall() and continues processing the incoming call.)	**Library receives ISDN_ERROR and releases host CRN #1 CCEV_TASKFAIL <--	NULL	Firmware detects the collision prior to sending out the SETUP message to the network. Precedence is given to the incoming call. Firmware CRN #1 is released. ISDN_ERROR <--
	Host CRN # 2 assigned CCEV_OFFERED <--	OFFERED	CALL_INCOMING <--
cc_AcceptCall() (option) -->	Call_Alert -->		CALL_ALERT -->	Alerting -->
	CCEV_ACCEPTCALL <--	ACCEPTED	CALL_ALERT_ACK <--
cc_AnswerCall() -->	Call_Connected -->		*B channel cut-thru CALL_CONNECT -->	Connect -->
	CCEV_ANSWERCALL <--	CONNECTED	CALL_CONNECT_ACK <--	Conn_ACK <--
*Application may connect a voice channel to the B channel. **Note that the CCEV_TASKFAIL event may occur anytime between calling cc_MakeCall() and the receipt of the CCEV_ANSWERCALL event.

Simultaneous disconnect (any state)

A simultaneous disconnect condition occurs when both the application and the network attempt to disconnect the call. The following scenarios are written for the asynchronous programming model. For synchronous programming, CCEV_DROPCALL will terminate cc_DropCall( ).

The first simultaneous disconnect scenario covers the following conditions:

• Glare at firmware - the firmware sees DISCONNECT first.
• cc_DropCall( ) arrives before release command is sent - the network disconnects first while cc_DropCall( ) arrives at the firmware before a release command is sent to the network.

NOTE:

This scenario assumes the default firmware-controlled disconnect process.

Asynchronous Programming

Application	Device Driver	State	Firmware	Network
		CONNECTED
	CCEV_ DISCONNECTED <--	DISCONNECTED	CALL_DISC <--	Disconnect <--
*cc_DropCall( )	Call_Disconnected (cause value =0) -->	IDLE	Firmware does nothing here until Release is sent	Release -->
	**CCEV_DISCONNECTED <--			Release -->
	CCEV_DROPCALL <--		CALL_CLEARED <--	Rel_Comp <--
***cc_ReleaseCall( ) -->	Call_Dealloc -->
	Driver releases CRN Return <--	NULL	F/W releases CRN CALL_DEALLOC_ACK <--
*Application should set a "drop call" flag. **Application should ignore CCEV_DISCONNECTED if "drop call" flag is set. ***cc_ReleaseCall( ) always clears "drop call" flag.

The next scenario covers the following simultaneous disconnect conditions:

• cc_DropCall( ) arrives after Release command is sent - the network disconnects first while cc_DropCall( ) arrives at the firmware after a Release command is sent to the network.
• Glare happens on the wire - the firmware sees the cc_DropCall( ) function call first.

Asynchronous Programming

Application	Device Driver	State	Firmware	Network
		CONNECTED
	CCEV_DISCONNECTED <--	DISCONNECTED	CALL_DISC <--	Disconnect <--
				Release -->
				Rel_Comp <--
cc_DropCall( ) -->	Call_Disconnected (cause value =0) -->	IDLE
	CCEV_DROPCALL <--		CALL_CLEARED <--
	ISDN_Block_Ts (sync model only)		Incoming call blocked
cc_ReleaseCall( ) -->	Call_Dealloc -->
	Driver releases CRN Return <--	NULL	F/W releases CRN CALL_DEALLOC_ACK <--

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