function open_customerservice() {
		window.open('customerservice/customerservice_index.php', 'CustomerService','toolbar=no,directories=no,status=no,scrollbars=yes,resize=no,menubar=no,width=600,height=500,top=100,left=200');
		return false;
	}

	function open_faq() {
		window.open('customerservice/customerservice_question.php?cat=algemeen', 'CustomerService','toolbar=no,directories=no,status=no,scrollbars=yes,resize=no,menubar=no,width=600,height=500,top=100,left=200');
		return false;
	}

	function open_cheapertelco() {
		window.open('cheapertelco.php', 'Cheapertelco','toolbar=no,directories=no,status=no,scrollbars=yes,resize=no,menubar=no,width=600,height=500,top=100,left=200');
		return false;
	}

	function open_tellafriendemail() {
		window.open('tellafriend_email.php', 'Tellafriend','toolbar=no,directories=no,status=no,scrollbars=yes,resize=no,menubar=no,width=600,height=500,top=100,left=200');
		return false;
	}

	function open_flyerservice() {
		window.open('flyerservice.php', 'Flyerservice','toolbar=no,directories=no,status=no,scrollbars=yes,resize=no,menubar=no,width=600,height=500,top=100,left=200');
		return false;
	}

	function open_mailarticle(articlelink) {
		window.open(articlelink, 'SendArticleToFriend','toolbar=no,directories=no,status=no,scrollbars=yes,resize=no,menubar=no,width=600,height=500,top=100,left=200');
		return false;
	}
		
	function open_printrates() 
	{
		window.open('rates_printer.php','tarife','scrollbars=yes, status=yes, menubar=yes, toolbar=yes, location=no, resizable=yes, width=700,height=450');
		return false;
	}
	
	function open_pop_callcharges() {
		window.open('pop_tariffnotice.php','tariffnotice','scrollbars=yes,status=no,resize=no,width=480,height=380'); 
		return false;
	}	

	
	function isEmail(address) {
		var isValid = false;
		// basic checks (relying on lazy evaluation for correct behaviour!)
		// not empty
		// at least 7 characters (x@yy.zz)
		// has @
		// has only 1 @
		// has at least one . (domain.ext)
		isValid = (address!=null) 
		       && (address.length >= 7) 
		       && (address.indexOf('@')!=-1) 
		       && (address.indexOf('@') == address.lastIndexOf('@'))
		       && (address.indexOf('.')!=-1)
		;
		
		if (isValid) {
			var parts = address.split('@');
			var name  = parts[0].split('.');
			var host  = parts[1].split('.');
			var regName  = new RegExp("^([!#$%&*+-/0-9=?A-Z^_a-z{}~]+)$"); // at least length 1
			var regLabel = new RegExp("^(^[-0-9A-Za-z][-0-9A-Za-z]+)$"); // at least length 2
			var regExt   = new RegExp("^([A-Za-z]{2,63})$"); // at least length 2
			var i;
			for (i=0; i < name.length; i++) {
				isValid = isValid && (name[i].search(regName) != -1);
			}
			for (i=0; i < host.length-1; i++) {
				isValid = isValid && (host[i].search(regLabel) != -1) && (host[i].length <= 63);
			}
			isValid = isValid && (host[host.length-1].search(regExt) != -1);
		}
		return isValid;
	}	
		
	function checkNews()
	{
		if (isEmail(document.news.email.value))
		{
			document.news.submit();
			return true;
		}
		else 
		{
			alert('Your email address is incorrect.\nPlease check the address and try again.');
			return false;
		}
	}
	
	function checkNewsU()
	{
		if (isEmail(document.news2.email.value))
		{
			document.news2.submit();
			return true;
		}
		else 
		{
			alert('Your email address is incorrect.\nPlease check the address and try again.');
			return false;
		}
	}	
	
	function noenter() 
	{
		return !(window.event && window.event.keyCode == 13); 
	}	
	
	function CheckTellafriendForm() 
	{
		var InputName  = document.tellafriend_form.name.value;
		var InputEmail = document.tellafriend_form.email.value;
		var InputFriend1 = document.tellafriend_form.emailfriend1.value;
		var InputFriend2 = document.tellafriend_form.emailfriend2.value;
		var InputFriend3 = document.tellafriend_form.emailfriend3.value;
		
		if ((InputName!='') && (InputEmail!='') && (InputFriend1!='')) {
			if (isEmail(InputEmail)){
				if (isEmail(InputFriend1)) {
					if ((InputFriend2=='') || isEmail(InputFriend2)) {
						if ((InputFriend3=='') || isEmail(InputFriend3)) {
							document.tellafriend_form.submit();
						} else {	alert('The entered email address for friend ' + ' 3 ' + 'is incorrect.');	}
					} else {		alert('The entered email address for friend ' + ' 2 ' + 'is incorrect.');	}
				} else {			alert('The entered email address for friend ' + ' 1 ' + 'is incorrect.');	}
			} else { 			alert ('Your email address is incorrect.\nPlease check the address and try again.'); }
		} else { 				alert ('Please fill out all mandatory fields.');	}
	}
	
	
	function checkEmail(thisform)
	{
		if (isEmail(thisform.email.value))
		{			
			return true;
		}
		else 
		{
			alert('Your email address is incorrect.\nPlease check the address and try again.');
			return false;
		}
	}