A PhoneNumberValidator validator is assigned to arg1(first argument tag)
<?xml version="1.0"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> <mx:RemoteObject id="ro" destination="roDest"> <mx:method name="setData"> <mx:arguments> <arg1>{text1.text}</arg1> <arg2>{text2.text}</arg2> </mx:arguments> </mx:method> </mx:RemoteObject> <mx:TextInput id="text1" /> <mx:TextInput id="text2" /> <mx:PhoneNumberValidator source="{ro.setData.arguments}" property="arg1" /> </mx:Application>