cc_GetChanId( )

Description | Cautions | Example | Errors | See Also

Name:	cc_GetChanId(crn, chanId)
Inputs:	CRN crn	call reference number
	CHAN_ID *chanId	pointer to channel ID structure
Returns:	0 on success < 0 on failure
Includes:	cclib.h
Category:	Optional call handling
Mode:	synchronous
Technology:	BRI/2; BRI/SC

Description

The cc_GetChanId( ) function gets the last channel information received from messages for the specified CRN. This function is used after a call-related event is received for the board device (e.g., dtiB1)

Parameter	Description
crn:	The call reference number.
chanId:	Pointer to the Channel ID structure that contains the last channel preference known for the specified CRN.

Cautions

The channel ID information associated with a specific CRN may change after an incoming call is connected or answered.

Example

#include <windows.h> /* For Windows applications only */  
#include <stdio.h>  
#include <errno.h>  
#include "srllib.h"  
#include "dtilib.h"  
#include "cclib.h"  
/** Globals **/  
CRN normal_crn = 0;         /* crn of a normal call */  
CRN waitingcall_crn = 0;  
/** Function prototypes **/  
long event_handler(unsigned long event_handle);  
int callfail (CRN crn);  
int procdevfail (LINEDEV handle);  
void main( )  
{  
   LINEDEV boarddev;  
   .  
   .  
   if ( cc_Open ( &boarddev, "dtiB1", 0 ) < 0 )  
   {  
      printf ("Error opening board device: errno = %d\n", errno);  
      exit (1);  
   }  
   .  
   .  
   sr_setparm ( SRL_DEVICE, SR_MODELTYPE, &sr_mode );  
   sr_enbhdlr ( EV_ANYDEV, EV_ANYEVT, event_handler );  
   if ( cc_WaitCall (boarddev, &normal_crn, NULL, -1, EV_ASYNC) < 0 )  
      procdevfail (linedev);  
   .  
   .  
   .  
}  
long event_handler(unsigned long event_handle)  
{  
   CRN crn;  
   int event;  
   void *datap;  
   char ani_buf[CC_ADDRSIZE];  
   CHAN_ID chanId;  
   event  = sr_getevttype(event_handle);  
   datap  = sr_getevtdatap(event_handle);  
   cc_GetCRN(&crn, datap);  
   switch(event)  
   {  
      case CCEV_OFFERED:  
         cc_GetChanId(crn, &chanId);  
         switch(chanId.channel)  
         {  
            case NO_BCHAN:  /* waiting call */  
               cc_GetANI (crn, ani_buf);  
               if (strcmp (ani_buf, "9933000") == 0)  
               {  
                  waitingcall_crn = crn;  
                  /* If no resource is available, then an active one must be freed */  
                  if( cc_DropCall (active_crn, NORMAL_CLEARING, EV_ASYNC) < 0 )  
                     callfail(crn);  
                  /** Optionally, the active call can be put on Hold  
                  if( cc_HoldCall (active_crn, EV_ASYNC) < 0 )  
                     callfail(crn);  
                  **/  
               }  
               else /* this call is not for us */  
               {  
                  if( cc_DropCall (crn, NORMAL_CLEARING, EV_ASYNC) < 0 )  
                     callfail(crn);  
               }  
               break;  
            case DCHAN_IND:  /* non circuit switched calls */  
               /* Ignore this call */  
               break;  
            default:  /* normal call */  
               normal_crn = crn;  
               switch(chanId.mode)  
               {  
                  case PREFFERED:  
                     if( cc_AcceptCall(crn, EV_ASYNC) < 0 )  
                        callfail(crn);  
                     break;  
                  case EXCLUSIVE:  
                     if( cc_AcceptCall (crn, 0, EV_ASYNC) < 0 )  
                        callfail(crn);  
                     break;  
               }  
         }  
         break;  
      case CCEV_ACCEPT:  
         if( cc_AnswerCall (crn, 0, EV_ASYNC) < 0 )  
            callfail(crn);  
         break;  
      case CCEV_ANSWERED:  
         if(crn == waitingcall_crn)  
         {  
             normal_crn = crn;  
             waitingcall_crn = 0;  
         }  
         break;  
            case CCEV_HOLDACK:  
         if( (crn == normal_crn) && (callwaiting_crn != 0) )  
         {  
            cc_GetChanId(crn, &chanId);  
            freed_device = chanId.channel;  
            if( cc_AcceptCall(callwaiting_crn, num_rings, EV_ASYNC) < 0 )  
               callfail(crn);  
            active_crn = 0;  
         }  
         break;  
      case CCEV_DROPCALL:  
         if( cc_ReleaseCallEx (crn) < 0 )  
            callfail(crn);  
         if( (crn == normal_crn) && (callwaiting_crn != 0) )  
         {  
            cc_GetChanId(crn, &chanId);  
            if( cc_AcceptCall(callwaiting_crn, num_rings, EV_ASYNC) < 0 )  
               callfail(crn);  
         }  
         break;  
case CCEV_RELEASE:  
         if(active_crn == crn)  
            active_crn = 0;  
         else if(waitingcall_crn == crn)  
            waitingcall_crn = 0;  
         break;  
       .  
       .  
       .  
   }  
}  
int callfail (CRN crn)  
{  
   LINEDEV ld;  
   cc_CRN2LineDev (crn,&ld);  
   procdevfail (ld);  
}   
int procdevfail (LINEDEV handle)  
{  
   int reason;  
   char *msg;  
   reason = cc_CauseValue (handle);  
   cc_ResultMsg (handle,reason, &msg);  
   printf ("reason = %x - %s\n", reason, msg);  
}

Errors

If the function returns < 0 to indicate failure, use the cc_CauseValue( ) function to retrieve the reason code for the failure. The cc_ResultMsg( ) function can be used to interpret the reason code. Error codes are defined in the files ccerr.h, isdnerr.h, and isdncmd.h.

Error codes from the cc_GetChanId( ) function include the following:

Error Code	Description
ERR_ISDN_LIB | E_ISBADIF	Bad interface number
ERR_ISDN_LIB | E_ISBADCALLID	Bad call identifier
ERR_ISDN_LIB | E_ISBADTS	Bad time slot

See Also

• cc_AcceptCall( )
• cc_MakeCall( )

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