}

			// set the currently selected item
			SendMessage(g_hwndOpList, LB_SETCURSEL, 0, 0);

			break;

		case WM_COMMAND:
			switch (wParam) {			
				case IDM_EXTAPIA_QUIT:
					CleanupLB();
					EndDialog(hDlg, 0);
					break;

				case IDM_EXTAPIA_REG:
					{
						RegisterNewOperator();
						break;
					}

				default:
					bProcessedMsg = FALSE;
					break;
			}
			break;
		
		default:
			bProcessedMsg = FALSE;
			break;
	}

	return bProcessedMsg;
}

// ***************************************************************************
// Function Name: InitDialog
// 
// Purpose: Sizes a dialog box to be full screen and adds the menus
//
// Arguments:
//	hDlg = the HWND of the dialog box
//	nToolBarId = the ID of the menu bar to add
//
// Return Values:
//	TRUE if successful, FALSE otherwise
//
// Description:
//	This function simply takes an HWND for a dialog, makes it full screen, adds
//	a menu bar, and sets the title bar to be the title of the application.

BOOL InitDialog(const HWND hDlg, UINT nToolBarId)
{
	// Specify that the dialog box should stretch full screen
	SHINITDLGINFO shidi;
	ZeroMemory(&shidi, sizeof(shidi));
	shidi.dwMask = SHIDIM_FLAGS;
	shidi.dwFlags = SHIDIF_SIZEDLGFULLSCREEN;
	shidi.hDlg = hDlg;

	// set up Soft Keys menu
	SHMENUBARINFO mbi;
	ZeroMemory(&mbi, sizeof(SHMENUBARINFO));
	mbi.cbSize = sizeof(SHMENUBARINFO);
	mbi.hwndParent = hDlg;
	mbi.nToolBarId = nToolBarId;
	mbi.hInstRes = g_hInstance;

	// If we could not initialize the dialog box, return an error
	if (!(SHInitDialog(&shidi) && SHCreateMenuBar(&mbi))) {
		return FALSE;
	}

	// set the title bar
	VERIFY(SetWindowText(hDlg, g_szTitle));

	// In order to make Back work properly, it's necessary to 
	// override it and then call the appropriate SH API
	(void)SendMessage(mbi.hwndMB, SHCMBM_OVERRIDEKEY, VK_TBACK, 
					  MAKELPARAM(SHMBOF_NODEFAULT | SHMBOF_NOTIFY, 
								 SHMBOF_NODEFAULT | SHMBOF_NOTIFY));

	return TRUE;
}

// ***************************************************************************
// Function Name: TAPIProc
// 
// Purpose: Callback function for asynchronous TAPI calls
//
// Arguments: Standard TAPI callback arguments
//
// Return Values: None
//
// Description:
//	Normally, this function would respond to any messages created by calls to
//	asynchronous TAPI functions.  One would definitely want to keep track of the
//	request numbers so they could be matched to their replies.  However, since this 
//	program only has one asynchronous call, we just assume that anything that passes
//	through here was a reply to that call.

void CALLBACK TAPIProc(DWORD hDevice, DWORD dwMessage, DWORD dwInstance,
					   DWORD dwParam1, DWORD dwParam2, DWORD dwParam3)
{
	// since we only made one asynch request, we just want to see if it was
	// successful or not.  A dwParam2 of 0 indicates success.
	if (dwMessage == LINE_REPLY) {
		if (!dwParam2) {
			MessageBox(g_hDlg, TEXT("LINE_REPLY: Success!"), 
					   g_szTitle, MB_OK | MB_ICONINFORMATION);
		} else {
			MessageBox(g_hDlg, TEXT("LINE_REPLY: Failure"), 
					   g_szTitle, MB_OK | MB_ICONERROR);
		}
		// Update the Current Operator text box
		GetCurrentOperator(g_hDlg);
	}
}

// ***************************************************************************
// Function Name: GetCurrentOperator
// 
// Purpose: Get the current operator and update the dialog display
//
// Arguments:
//	hDlg - the dialog containing the IDC_EXTAPIA_CUROP control
//
// Return Values:
//	TRUE if successful, FALSE otherwise
//
// Side Effects:
//	Updates the text for control IDC_EXTAPIA_CUROP
//
// Description:
//	This function simply calls the lineGetCurrentOperator function and updates
//	the display with the results.

BOOL GetCurrentOperator(HWND hDlg)
{
	LINEOPERATOR CurrentOperator;
	if (lineGetCurrentOperator(g_hLine, &CurrentOperator)) {
		return FALSE;
	}
	SetDlgItemText(hDlg, IDC_EXTAPIA_CUROP, CurrentOperator.lpszLongName);

	return TRUE;
}

// ***************************************************************************
// Function Name: GetAvailableOperators
// 
// Purpose: Get the available operators and update the dialog display
//
// Arguments:
//	hDlg - the dialog containing the IDC_EXTAPIA_CUROP control
//
// Return Values:
//	TRUE if successful, FALSE otherwise
//
// Side Effects:
//	Updates the text in the listbox with HWND g_hwndOpList
//	Allocates memory to copy the operator strings
//
// Description:
//	This function simply calls the lineGetOperatorStatus function and updates
//	the display with the results.  If there are more operators than can fit in pbInit
//	it also temporarily allocates memory.

BOOL GetAvailableOperators(HWND hDlg)
{
	// set up the initial mega data structure
	BYTE pbInit[REASONABLE_BUFFER];
	LPLINEOPERATORSTATUS plosOperatorStatus = (LPLINEOPERATORSTATUS)pbInit;
	LPBYTE pLineOperatorStatusBytes = NULL;
	LPTSTR lpszItemData;
	DWORD dwNeededSize;
	int iResult;

	plosOperatorStatus->dwTotalSize = REASONABLE_BUFFER;
	if (lineGetOperatorStatus(g_hLine, plosOperatorStatus)) {
		return FALSE;
	}

	// check to see if our buffer was large enough
	if (plosOperatorStatus->dwNeededSize >= plosOperatorStatus->dwTotalSize) {
		// allocate a byte array and cast it to a LPLINEOPERATORSTATUS
		dwNeededSize = plosOperatorStatus->dwNeededSize;
		pLineOperatorStatusBytes = new BYTE[dwNeededSize];
		if (!pLineOperatorStatusBytes) {
			return FALSE;
		}
		plosOperatorStatus = (LPLINEOPERATORSTATUS)pLineOperatorStatusBytes;
		
		// call lGOS again to fill the new structure
		plosOperatorStatus->dwTotalSize = dwNeededSize;
		if (lineGetOperatorStatus(g_hLine, plosOperatorStatus)) {
			delete[] pLineOperatorStatusBytes;
			return FALSE;
		}
	}

	// set the pointer to the first available operator and iterate
	LPLINEOPERATOR ploOperator;
	DWORD dwOperatorNumber;
	ploOperator = (LPLINEOPERATOR)((LPBYTE)plosOperatorStatus+(plosOperatorStatus->dwAvailableOffset));
	for(dwOperatorNumber = 0; 
		dwOperatorNumber < plosOperatorStatus->dwAvailableCount; 
		dwOperatorNumber++) {
		// add the element to the listbox
		iResult = SendMessage(g_hwndOpList, LB_ADDSTRING, 0, (LPARAM) ploOperator->lpszLongName);

		// copy the lpszNumName and store the pointer as ItemData
		if (iResult >= LB_OKAY) {
			lpszItemData = _tcsdup(ploOperator->lpszNumName);
			if (!lpszItemData) {
				delete[] pLineOperatorStatusBytes;
				return FALSE;
			}
			SendMessage(g_hwndOpList, LB_SETITEMDATA, iResult, (LPARAM) lpszItemData);
		} else {
			delete[] pLineOperatorStatusBytes;
			return FALSE;
		}

		// increment the pointer
		ploOperator++;
	}

	// cleanup
	delete[] pLineOperatorStatusBytes;
	return TRUE;
}

// ***************************************************************************
// Function Name: RegisterNewOperator
// 
// Purpose: call lineRegister on the currently selected operator
//
// Arguments: none
//
// Return Values: none
//
// Description:
//	This function simply takes the currently selected member of g_hwndOpList and
//	tries to register it as a new operator.  lineRegister is asynchronous, so the
//	result of this call is posted to TAPIProc.

void RegisterNewOperator()
{
	LPTSTR lpszNumName;
	int iCurSel, iResult;

	iCurSel = SendMessage(g_hwndOpList, LB_GETCURSEL, 0, 0);
	if (iCurSel != LB_ERR) {
		// get the provider name
		lpszNumName = (LPTSTR) SendMessage(g_hwndOpList, LB_GETITEMDATA, 
										   (WPARAM) iCurSel, (LPARAM) 0);

		// now try to set the current provider
		// normally we would store this ID and verify it in TAPIProc, but since we are
		// only making one asynchronous request, we ignore this value...
		iResult = lineRegister(g_hLine, LINEREGMODE_MANUAL, 
							   lpszNumName, LINEOPFORMAT_NUMERIC);
	} else {
		MessageBox(NULL, TEXT("Unable to get current selection"),
				   TEXT("Error!!!"), MB_OK | MB_ICONERROR);
	}

}

// ***************************************************************************
// Function Name: CleanupLB
// 
// Purpose: free the strings pointed to by a listbox's itemdata
//
// Arguments: none
//
// Return Values: none
//
// Description:
//	This function simply iterates through the members of a listbox, gets their
//	item data values, which should be pointers to strings, and frees them.

void CleanupLB()
{
	int iResult;
	LPTSTR lpszNumName;
	
	// get the number of items in the listbox
	iResult = SendMessage(g_hwndOpList, LB_GETCOUNT, 0, 0);
	if (iResult != LB_ERR) {
		for (int i = 0; i < iResult; i++) {
			lpszNumName = (LPTSTR) SendMessage(g_hwndOpList, LB_GETITEMDATA, (WPARAM) i, (LPARAM) 0);
			free(lpszNumName);
		}
	}
}