User`s guide

Dialogic
®
System Release 6.0 PCI for Windows
®
Release Update, Rev 62 — January 30, 2008 171
Dialogic Corporation
Note: An extra LCON event may be seen after the first expected LCON is received but before
LCREV is received. This may occur due to the polarity reversal. When a polarity reversal
occurs, there is a momentary loss of loop current. If this duration is 100+ ms, this triggers
an LCON event (since an LCON event is defined as a transition from no loop current ->
loop current). The longer the duration of no loop current, the more likely it is that this will
cause the extra LCON event. Since the LCON is preceded by the LS_Net_Answer CAS
signal (seen in log with TSPTrace), this extra event is not an error, but merely the current
line condition.
Also, an extra LCREV event may be seen before LCOFF. This is because the Central
Office may reverse the polarity on the line, to counteract the polarity reversal done
previously, before terminating the call. This sequence of events is acceptable but may not
be seen in all cases. It depends on the Central Office.
1.48.2 Enabling Reception of the GCEV_EXTENSION Event
The GCEV_EXTENSION event indicates that unsolicited information is received from the
network or remote end point. Information about the event is contained in the
EXTENSIONEVTBLK structure, which is referenced via the extevtdatap pointer in the
METAEVENT structure associated with the GCEV_EXTENSION event.
The new GCEV_EXTENSION events are disabled by default. Use the standard Global
Call procedure for enabling reception of the GCEV_EXTENSION event by using
gc_util_insert_parm_val( ) to build a GC_PARM_BLK, followed by gc_SetConfigData( )
to enable the event. See the Dialogic
®
Global Call API Library Reference for further
information about these functions.
The following code snippets show how to enable and process the GCEV_EXTENSION
event. Note that:
• EXTENSIONEVT_CALLSTATUS_TRANSITION is the new bitmask to enable/disable
reception of call status transition events.
• CCSET_CALLSTATUS_TRANSITION is the setID.
• CCPARM_CST_TYPE is the parmID, with values:
• CC_CST_LCON
• CC_CST_LCOFF
Call Flow Sequence Function Events Received
Pre-call - Loop current is off.
Application makes outbound call. gc_MakeCall( ) GCEV_EXTENSION(CC_CST_LCON)
GCEV_DIALING
GCEV_ALERTING
Called (far end) party answers the call. GCEV_EXTENSION(CC_CST_LCREV)
GCEV_CONNECTED
Near end drops the call. gc_DropCall( ) GCEV_EXTENSION(CC_CST_LCOFF)
GCEV_DROPCALL
Application frees the device for another
call.
gc_ReleaseCallEx( ) GCEV_RELEASECALL