Mine

			function checkall(){
				var elements = document.getElementsByTagName('input');
				for (var j=0; j<elements.length; j++) {
					if(elements[j].type == 'checkbox' && elements[j].name !== 'Call'){
						if (elements[j].checked == 'true'){
							elements[j].checked = 'false';
						} else {
							elements[j].checked = 'true';
						}
						//elements[j].setAttribute('checked','true');
		   			} 	   			
 				}
			}