^\(?([+]31)-?6(\s?|-)([0-9]\s{0,3}){8}$

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<script type="text/javascript" charset="utf-8">
    $(document).on('ready pjax:scriptcomplete',function(){ 
        $('#question{QID}  input[type="text"]').inputmask({
            'mask': '(+31) 6 99999999',
            'placeholder': '_',
            'removeMaskOnSubmit': false,
            'rightAlign': false,
        });
 
  });
</script>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery.mask/1.14.16/jquery.mask.js"></script>
<script type="text/javascript" charset="utf-8">
    $(document).on('ready pjax:scriptcomplete',function(){ 
      
         $('#question{QID} input[type="text"]').mask('+31 6 00000000', { 
                placeholder: "+31 6 12345678" 
         });
    });
</script>