正在看一段程序

struct KM_SETUP_TAB
{
    INT8U *lcdMessage;
    struct KM_SETUP_TAB *nextMenuPtr;
    INT32S (*SetupItemFunc) (S_PHONE_DATA_BASE *devptr,INT8S msg);
    INT32U  wAuthority;
} ;
typedef struct KM_SETUP_TAB S_KM_SETUP_TAB;

static S_KM_SETUP_TAB KM_AddressBook_EN[]=
{
    {"1.Search",        NULL,            swKM_aBookSearch,    KSETUP_AUTH_NONE    },    
    {"2.Add entry",        NULL,            swKM_aBookAdd,        KSETUP_AUTH_NONE    },
    {"3.Speed dial",    NULL,            swKM_aBookSpeedDial,    KSETUP_AUTH_NONE    },
    {"4.Erase all",        NULL,            swKM_aBookEraseAll,    KSETUP_AUTH_NONE    },
    {NULL,                 NULL,            NULL,            0            },
    {"Name:",             NULL,            NULL,            0            },
    {"Number:",            NULL,            NULL,            0            },
    {"SIP Phone:",        NULL,            NULL,            0            },
    {"Dial key",        NULL,            NULL,            0            },
    {"P-Book is empty", NULL,            NULL,            0            },
    {"Search:",            NULL,            NULL,            0            },    
    {"P-Book is full",  NULL,            NULL,            0            },     
    {"Press M1..Mx to", NULL,            NULL,            0            },       
    {"strore number",   NULL,            NULL,            0            },         
    {NULL,                 NULL,            NULL,            0            }
};

static INT32S swKM_aBookAdd(S_PHONE_DATA_BASE *devptr,INT8S msg)
{
    //S_DB_SIP_ADDR_PORT  *BookPtr; 
    
    if(devptr->FunState == FUN_STATE_SELECTION)
    {
        abkSorting(devptr);
        
        devptr->aBkName[0]=0;
        devptr->aBkPhoneNo[0]=0;
        devptr->aBkJob=0;
        devptr->Update=FALSE;
        if(devptr->aBkTotals==C_DB_SIP_PHONEBOOK_NUM)
        {
            CLR_LCD_SCREEN();
            PRINT_LCD_LINE_STRING(0,devptr->ItemList[PROMPT_7],C_NOT_UPDATE_LCD_BUF);
        }        
    }
    if(devptr->aBkTotals==C_DB_SIP_PHONEBOOK_NUM)
    {
        devptr->FunState = FUN_STATE_SELECTION;        // exit
    }
    else
    {        
        //devptr->aBkSelect=devptr->aBkTotals;
        devptr->temp=TRUE;    // add item
        abkEditEntry(devptr,msg);
    }    
}

请问为什么在调用swKM_aBookAdd 时可以不带参数，要是可以不带的话，那些参数从哪里来呢？
实在是郁闷！