Mask nono digito

var noneDig = false;
$('.mobile').mask("(99) 9999-9999").keydown(function(){
    var phone, $element;
    $element = $(this);
    phone = $element.val().replace(/\D/g, '');
    if(phone == "11" && phone.length == 2 && !noneDig){
        $element.mask("(11) 99999-999?9");
        noneDig = true;

    }else if(phone == "11" && phone.length == 2 && noneDig){
        $element.mask("(99) 99999-999?9");

    }else if(phone.length < 2 && noneDig){
        $element.mask("(99) 9999-9999");
        noneDig = false;
    }
});