5.8. Overlap Send and Receive

The S77 call control library supports overlap sending using the gc_SendMoreInfo( ) function.

Two methods of overlap receiving are supported, the preferred method, and an older method maintained for backward compatibility reasons only. Both methods are described below.

The preferred method for implementing overlap receiving is as follows:

1. Issue gc_CallAck(GCACK_SERVICE_INFO) to determine if digits are available.
2. Receive a GCEV_MOREINFO event.
3. Use gc_ResultValue( ) to determine the status, which is one of the following:
   • GCRV_INFO_PRESENT_ALL - The requested digits are now available.
   • GCRV_INFO_PRESENT_MORE - The requested digits are now available. More/additional digits are available.
   • GCRV_INFO_SOME_TIMEOUT - Only some digits are available due to a time out.
   • GCRV_INFO_SOME_NOMORE - Only some digits are available, no more digits will be received.
   • GCRV_INFO_NONE_TIMEOUT - No digits are available due to a time out.
   • GCRV_INFO_NONE_NOMORE - No more digits are available.
4. Issue gc_GetCallInfo(DESTINATION_ADDRESS) to retrieve the digits.
5. If the status returned via GCEV_MOREINFO in step 3 indicates that more digits are available, the application can do the following:
   • Issue gc_ReqMoreInfo( ) to request the additional digits.
   • Receive a GCEV_MOREINFO event with a status as indicated in step 3 above.
   • Issue gc_GetCallInfo(DESTINATION_ADDRESS) to retrieve the additional digits.
6. Repeat step 5 until all information has been retrieved.

The following method of overlap receiving continues to be supported for backward compatibility reasons only:

1. Issue gc_CallAck(GCACK_SERVICE_DNIS) identifying the number of digits to retrieve (dnis.accept) in the GC_CALLACK_BLK structure pointed to by the callack_blkp function parameter.
2. Receive a GCEV_MOREDIGITS event.
3. Issue gc_GetDNIS( ) to retrieve the digits.

Note: To retrieve a certain number of digits at a time, specify that number in the dnis.accept field and repeat steps 1, 2 and 3 above until all information has been retrieved.

See the Global Call API Programming Guide for more detailed information on overlap sending and receiving in general and the Global Call API Library Reference for more information about the functions mentioned above.

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