Modem Communication ! Urgent

Edited text of question

Edited text of question

For Win32?

Here is some code for opening any comport and setup parameters.
nPort: 0=COM1, 1=COM2....

*************

HANDLE OpenCommPort(int nPort, int nBaudrateIdx)
{

    HANDLE hPort;
    CString strPort;
    if(nPort<10)
        strPort.Format(_T("COM%d"), nPort);
    else
        strPort.Format(_T("\\\\.\\COM%d"), nPort);

    // Open COM1.....COMx
    hPort = CreateFile(strPort,GENERIC_READ|GENERIC_WRITE,
        0,    /* comm devices must be opened w/exclusive-access */
        NULL, /* no security attrs */
        OPEN_EXISTING, /* comm devices must use OPEN_EXISTING */
        0,
        NULL  /* hTemplate must be NULL for comm devices */
        );
    if(hOPSPort == INVALID_HANDLE_VALUE)
        return NULL;

    // Setup timeout values for reading and writing to the port
    COMMTIMEOUTS ctmo;
    ctmo.ReadIntervalTimeout = 100;
    ctmo.ReadTotalTimeoutMultiplier = 1;
    ctmo.ReadTotalTimeoutConstant = 2000;
    ctmo.WriteTotalTimeoutMultiplier = 1;
    ctmo.WriteTotalTimeoutConstant = 1000;
    SetCommTimeouts(hPort, &ctmo);

    const int br[] = { 300, 1200, 2400, 4800, 9600, 14400, 19200 };

    // Setup port to use CTS/RTS hardware flow control with 8 databits
    // 1 stopbit and no parity.

    DCB dcb;
    ZeroMemory(&dcb, sizeof(dcb));
    dcb.DCBlength = sizeof(DCB);
    dcb.BaudRate = br[nBaudrateIdx];
    dcb.fBinary = TRUE;
    dcb.fParity = 0;
    dcb.fOutxCtsFlow = 1;
    dcb.ByteSize = 8;
    dcb.Parity = NOPARITY;
    dcb.StopBits = 0;
    dcb.fDtrControl = DTR_CONTROL_ENABLE;
    dcb.fRtsControl = RTS_CONTROL_ENABLE;
    dcb.fAbortOnError = FALSE;
    if(!SetCommState(hPort, &dcb))
    {
        CloseHandle(hPort);
        hPort = INVALID_HANDLE_VALUE;
        return NULL;
    }

    return hPort;
}

********

To read and write to the port, just use the normal ReadFile()/WriteFile() functions

Here is an example of how to reset the modem:

BOOL ResetModem(HANDLE hPort)
{
    CString sCmd = _T("Z\n");

    DWORD dwIOLen;
    if(WriteFile(hPort, sCmd, sCmd.GetLength(), &dwIoSize, NULL))
    {
        return TRUE;
    }

    return FALSE;
}

Off-cause you would want to check the responses from the modem when sending
commands or dialing but that is just basic Win32 IO.

Please refer to online manual about the following functions.
GetCommState
SetCommState
SetupComm
CreateFile

There is an example on the VC5 CD: \Devstudio\Vc\Samples\Sdk\Win32\Comm
Theses sites can also give you some help.

http://www.qfax.com/
http://www.goodnet.com/~esnible/winsock.html 
 

hi piano_boxer & trestan,
              Thanks for your reply . I understood your  code .
 Infact I have  programmed the COM port myself in a similar way  for communicating  with Barcode readers and printers but I  wanted  to  know  how to  dial a  telephone number by a
program  when the modem is connected to a com port and
 also how to send  data over telephone wires .

Hi piano_boxer,
         Thanks  for your  answer .