function update_character_length(){
	if($('message').value.length >= 160){
		$('message').value = $('message').value.substring(0,160);
	}
	$('message_length').innerHTML = "Character length (max 160): " + $('message').value.length;
}

function validate_subscriber_form(){
	var error = "";
	var emailFilter=/^.+@.+\..{2,6}$/;
	if (!(emailFilter.test($('subscriber_email').value))) { 
	       error = "Please enter a valid email address.\n";
	}
	
	if($('subscriber_phone_number').value != '' && $('subscriber_cell_carrier_id').value == ''){
		error = "You must select a cell carrier.\n"
	}
	
	if(error != ""){
		alert(error);
		return false;
	}
}