$.validator.addMethod("mobileNL", function(value, element) {
	return this.optional(element) || /^((\+|00(\s|\s?\-\s?)?)31(\s|\s?\-\s?)?(\(0\)[\-\s]?)?|0)6((\s|\s?\-\s?)?[0-9]){8}$/.test(value);
}, "Please specify a valid mobile number");
