3.2. Accessing Caller ID Information

Applications using the Caller ID feature can process Caller ID information in the following ways:

• For CLASS or ACLIP, the Caller ID information is received from the service provider between the first and second ring. Set the ring event in the application to occur on or after the second ring. The ring event indicates reception of the CLASS or ACLIP Caller ID information from the CO.
• For CLIP or JCLIP, the Caller ID information is received from the service provider before the first ring. Set the ring event in the application to occur on or after the first ring. The ring event indicates reception of the CLIP Caller ID information from the CO.

The Caller ID information is available for the call from the moment the ring event is generated (if the ring event is set in your application as stated above) until one of the following occurs:

• If the call is answered (the application channel goes off-hook), the Caller ID information is available to the application until the call is disconnected (the application channel goes on-hook).
• If the call is not answered (the application channel remains on-hook), the Caller ID information is available to the application until rings are no longer received from the CO (signaled by ring off event, if enabled).

To determine if Caller ID information has been received from the CO, before issuing a dx_gtcallid( ) or dx_gtextcallid( ) Caller ID function, check the event data in the event block. When the ring event is received, the event data field in the event block is bitmapped and indicates that Caller ID information is available when bit 0 (LSB) is set to 1. For details on the event block and function code examples, refer to the Voice Software Reference: Programmer's Guide.

NOTE:

If the call is answered before the Caller ID information has been received from the CO, Caller ID information will not be available to the application.

If the call is not answered and the ring event is received before the Caller ID information has been received from the CO, Caller ID information will not be available until the beginning of the second ring (CLASS, ACLIP) or the beginning of the first ring (CLIP, JCLIP).

Based on the Caller ID options provided by the CO and for applications that require only the calling line Directory Number (DN), issue the dx_gtcallid( ) function to get the calling line DN.

Based on the Caller ID options provided by the CO and for applications that require additional Caller ID information, issue the dx_gtextcallid( ) function for each type of Caller ID message required. As an argument in the dx_gtextcallid( ) function, the type of Caller ID message to access is specified (infotype).

The dx_wtcallid( ) function is a Caller ID Convenience function provided to allow applications to wait for a specified number of rings (as set for the ring event) and returns the calling station's Directory Number (DN).

The dx_wtcallid( ) function combines the functionality of the following:

• dx_setevtmsk( ) voice function
• dx_getevt( ) voice function
• dx_gtcallid( ) Caller ID function

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