//Obtain the UI Service
ServiceReference uiServiceRef 
    = context.getServiceReference(UIService.class.getName());
UIService uiService =
    (UIService)context.getService(uiServiceRef);

//Check if there is an "Add contact" dialog, exported from the
//current UI implementation.
boolean isDialogExported 
    = uiService.isDialogExported(UIService.DIALOG_ADD_CONTACT);

if(isDialogExported) {
    //Obtains the "Add contact" dialog
    ExportedDialog configDialog = uiService
        .getApplicationDialog(UIService.DIALOG_ADD_CONTACT);

    //If the "Add contact" dialog is not currently visible, show it.
    if(!configDialog.isDialogVisible()) {
        configDialog.showDialog();
    }
}