Usage: $('.phone').numeric();

jquery.numeric.plugin.js

// Numeric plugin
(function($) {
    $.fn.numeric = function() {         
        return this.each(function() {
            $(this).keydown(function(e) {
                var key = e.charCode || e.keyCode || 0;                 
                return (key == 8 || key == 9 || key == 46 || (key >= 35 && key <= 40) || (key >= 48 && key <= 57) || (key >= 96 && key <= 105));
            });
        });
    };
})(jQuery);