4.3.11. gc_SetInfoElem( )

The gc_SetInfoElem( ) function allows the application to add ISUP message parameters (that is, information elements) to outgoing messages sent by the SS7 call control library while executing a Global Call call control function. The format of the information elements is typically identical to the ISUP format, with the exception that all parameters are formatted as optional parameter (parameter name, length, and contents). It is possible to add multiple information elements in one gc_SetInfoElem( ) function call. The parameters must be put in an S7_IE_BLK structure, a pointer to which is set in the cclib field of the GC_IE_BLK specified as argument to the function. The following code fragment illustrates the use of the function:

/*  Add User-to-user information to Initial Address Message */ 
S7_IE_BLK ie_blk; 
GC_IE_BLK gc_ie_blk;  
ie_blk.length = 5; 
ie_blk.data[0] = 0x20;  /* Parameter name - User-to-user info */ 
ie_blk.data[1] = 0x03;  /* Parameter length - 3 bytes */ 
ie_blk.data[2] = 'A';   /* Parameter value - 1st byte */ 
ie_blk.data[3] = 'B';   /* Parameter value - 2nd byte */ 
ie_blk.data[4] = 'C';   /* Parameter value - 3rd byte */  
gc_ie_blk.gclib = NULL; 
gc_ie_blk.cclib = &ie_blk; 
if (gc_SetInfoElem(linedev, &gc_ie_blk) != GC_SUCCESS) /* Process error */ 
if (gc_MakeCall(linedev, &crn, "7124311", NULL, 15, EV_ASYNC) != GC_SUCCESS) 
/* Process error */  

Note: Parameter values (such as 0x20 in the example above, which corresponds to the User-to-User Information parameter) should correspond to parameter values from the ISUP/TUP specifications.

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