function check() {
  for (i = 0; i < document.forms[0].elements.length; i++) {
     var name = document.forms[0].elements[i].name;
     if (name == null) {
       continue;
     }
     var value = document.forms[0].elements[i].value;
     
     if ((name == "tel") || (name == "mobile")) {
       value = value.replace(/\+/g, "00");
       value = value.replace(/\//g, ""); 
       value = value.replace(/\(/g, "");
       value = value.replace(/'/g, "");
       value = value.replace(/\./g, "");
       value = value.replace(/[a-zA-Z]/g, "");
       value = value.replace(/ /g, "");
       document.forms[0].elements[i].value = value;
     }

     if (value == "") {
       if (name == "prename") {
         alert('Please enter your first name.');
	 document.forms[0].elements[i].focus();
         return false;
       }
       if (name == "name") {
         alert('Please enter your last name.');
	 document.forms[0].elements[i].focus();
         return false;
       }
       if (name == "street") {
         alert('Please enter street name.');
	 document.forms[0].elements[i].focus();
         return false;
       }
       if (name == "nr") {
           alert('Please enter street number.');
  	 document.forms[0].elements[i].focus();
           return false;
         }
       if (name == "zip") {
         alert('Please enter zip code.');
	 document.forms[0].elements[i].focus();
         return false;
       }
       if (name == "city") {
         alert('Please enter city.');
	 document.forms[0].elements[i].focus();
         return false;
       }
     if (name == "country") {
         alert('Please enter country.');
	 document.forms[0].elements[i].focus();
         return false;
       }
     if (name == "email") {
         alert('Please enter your email address.');
	 document.forms[0].elements[i].focus();
         return false;
       }
  }
  }
  return true;
}