jQuery MaskedInput plugin BR phone (9 digits) mask

maskedinput.br.js

//optimized

$(function(){
    jQuery.fn.brTelMask = function () {

        return this.each(function () {
            var $el = $(this);
            $el.mask("(99) 9999-9999?9");

            $el.keyup(function () {
                var phone = $el.val().replace(/\D/g, '');
                if (phone.length > 10) {
                    $el.mask("(99) 99999-999?9");
                } else if(phone.length > 9){
                    $el.mask("(99) 9999-9999?9");
                }
            });
        });
    };

    $('.telefone').brTelMask();
});