device features.
 */
 
-#define DRIVER_VERSION "v0.7.1"
+#define DRIVER_VERSION "v0.7.2"
 #define DRIVER_AUTHOR "Matthias Urlichs <smurf@smurf.noris.de>"
 #define DRIVER_DESC "USB Driver for GSM modems"
 
        }
 }
 
+
+/** send RTS/DTR state to the port.
+ *
+ * This is exactly the same as SET_CONTROL_LINE_STATE from the PSTN
+ * CDC.
+*/
 static int option_send_setup(struct usb_serial_port *port)
 {
        struct usb_serial *serial = port->serial;
        struct option_port_private *portdata;
-
+       int ifNum = serial->interface->cur_altsetting->desc.bInterfaceNumber;
        dbg("%s", __FUNCTION__);
 
-       if (port->number != 0)
-               return 0;
-
        portdata = usb_get_serial_port_data(port);
 
        if (port->tty) {
 
                return usb_control_msg(serial->dev,
                                usb_rcvctrlpipe(serial->dev, 0),
-                               0x22,0x21,val,0,NULL,0,USB_CTRL_SET_TIMEOUT);
+                               0x22,0x21,val,ifNum,NULL,0,USB_CTRL_SET_TIMEOUT);
        }
 
        return 0;