1.18. D Channel Status

When using DM3 boards, a GCEV_D_CHAN_STATUS event is always generated once the board device is initialized and the initial D channel status is known. The resulting value associated with the event indicates this initial D channel status. Any subsequent change in the D channel status is also notified by means of GCEV_D_CHAN_STATUS event. When using Springware boards, when the initial D channel status was UP, no initial event was generated. When using DM3 boards, an initial event is always generated, regardless of the initial status of the D channel.

On download, by default both the trunk and channels are out of service. When the first gc_OpenEx( ) is executed on a device, the trunk (D channel) and the channel (B channel) associated with the device are placed into service (trunk in service, channel idle). Although the channel is IDLE, calls cannot be received or processed until gc_WaitCall( ) is issued. When the application uses gc_Close( ) to close the channel, the channel returns to out of service, but the trunk remains in service.

The application should use the gc_ResultValue( ) function to find the reason (UP or DOWN) associated with the GCEV_D_CHAN_STATUS event. A reason of UP indicates that the D channel is active and the gc_GetFrame( ) and gc_SndFrame( ) functions can be used to get or send frames respectively. The gc_GetLinedevState( ) function can be used to retrieve the status of the line device. See the Global Call API Library Reference for more information.

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