if (document.images) {
  var phone_g=new Image();
  phone_g.src="/images/phone-g.png";
  var phone_y=new Image();
  phone_y.src="/images/phone-y.png";
  var mail_g=new Image();
  mail_g.src="/images/mail-g.png";
  var mail_y=new Image();
  mail_y.src="/images/mail-y.png";  

  function one_change(the_name, the_source) {
    if (document.images) {
      document.images[the_name].src=eval(the_name + "_" + the_source + ".src");
    }
  }
}