Sends a message to the ISDN stack, with optional attached data.

DWORD isdnSendMessage ( CTAHD ctahd,
ISDN_MESSAGE *message,
void *pdata,
unsigned size )

ctahd CTA context handle associated with a D channel, returned by ctaCreateContext.

message Pointer to ISDN_MESSAGE structure, as follows:

typedef struct ISDN_MESSAGE
{
  nai_t nai;         /* Network access interface index */
  ent_id_t from_ent; /* Message source */
  ent_id_t to_ent;   /* Message destination */
  sapi_t to_sapi;    / * Destination Service Access Point */ 
union {
  add_t conn_id;     /* Connection identifier for the ACU layer */
  add_t crv;         /* Call Reference value for the NS layer. Not used. */
  add_t ces;         /* Connection Endpoint suffix (DL later upper half) */
  add_t tei;     /* Terminal Endpoint id (DL layer lower half). Not used. */
  add_t chani;       /* Physical layer channel identifier. Not used. */
} add;
   code_t code;      /* Primitive code unique only between two entities */
  WORD inf0;         /* Information location 0 */
  WORD inf1;         /* Information location 1 */
  WORD inf2;         /* Information location 2 */
  WORD inf3;         /* Information location 3 */
  WORD inf4;         /* Information location 4 */
  WORD data_size;    /* Size of data to follow   */
  WORD pad;          /* Pad */
  DWORD userid;      /* User ID */
} ISDN_MESSAGE;

pdata Pointer to the message data (if any). The data is specific to the type of message specified in ISDN_MESSAGE.

size Size of data block referenced by pdata. size must match the data_size field in the ISDN_MESSAGE structure.

• SUCCESS
• CTAERR_BAD_ARGUMENT
  This return value means any of the following:
  • The message argument is NULL.

  • The pdata is NULL but size is non zero.

  • The data_size in the message does not match the size parameter.

  • The size of the data exceeds MAX_ISDN_BUFFER_SIZE.

• CTAERR_INVALID_CTAHD
  The CTA context handle is invalid.

• ISDNEVN_SEND_MESSAGE
  The event value field contains one of the following: SUCCESS
  ISDNERR_BAD_NAI
  The network access identifier (NAI) in the message structure is not valid. The NAI must be less than MAX_NAI.
  ISDNERR_BUFFER_TOO_BIG
  The size of the buffer is too large.

This function sends a message with optional attached data to the ISDN subsystem. Any ISDN-specific command can be sent to any layer of the protocol stack using this function. The ISDN_MESSAGE structure contains the addressing information for the message.

The size field of the CTA event contains the user id for the message, as specified in the userid field in ISDN_MESSAGE. This value is sent to distinguish between multiple messages sent to the protocol stack. ISDN_ USERID_ASYNC is reserved for events initiated by the protocol stack.

isdnReleaseBuffer

sample_send_message (CTAHD ctahd, int mycode)
{
CTA_EVENT     event;
DWORD         ret;
ISDN_MESSAGE  imsg={0};
code_t        code;
unsigned char idata[MAX_ISDN_BUFFER_SIZE];
unsigned      datasize;
;
{
;
/*
** Protocol already started
*/
imsg.nai = 0;

/*
** when using ACU, all messages should be directed
** to ENT_ACU and the ACU_SAPI within it.
** The from field should always be ENT_API.
*/
imsg.from_ent = ENT_API;
imsg.to_ent   = ENT_CC;
imsg.to_sapi  = ACU_SAPI;

/*
** The connection id is the logical connection number.
** For ACU, the lowest unused connection id value must be used.
*/
imsg.add.conn_id = myGetLowestConnectionId();

/*
** Build the contents of the message for place call, release call, etc.
** This should fill the idata with the message contents and return the 
** used part of the data buffer in datasize argument and the code for the 
** function requested (ACU_CONN_RQ, ACU_CLEAR_RQ, etc).
*/
myBuildMessage( mycode, idata, &datasize, &code);
imsg.datasize = datasize;
imsg.code     = code;

/*
** Add an ISDN-specific user id to identify this message if it fails:
*/
imsg.userid = myGetNextMessageId();

ret = isdnSendMessage( ctahd, &imsg, idata, datasize);
if( ret != SUCCESS)
{
    ctaGetText(ctahd, ret, errortext, 40;
    printf("SEND_FAIL: %s mg id=%x\n", errortext, imsg.userid );
    return MY_ERROR_SEND_FAILED;
}
myWaitForEvent( ctahd, &event)
if( event.value != SUCCESS)
{
    ctaGetText(ctahd, event.value, errortext, 40);
    printf("SEND_FAIL: %s mg id=%x\n", errortext, imsg.userid );
    return MY_ERROR_SEND_FAILED;
}
...
}