how do i control the add to cart landing page?

Please change the line:
if($row->type_of_product=='phone') $plan=true;
to:
if($row->type_of_product=='phone') $phone=true;

Then, make sure that you selected the "type of product" in your product edition screen and saved the product information.

Then, try again.

$phone = $plan = false;
foreach($this->rows as $i => $row){
if($row->type_of_product=='plan') $plan=true;
if($row->type_of_product=='phone') $phone=true;
}
$app =& JFactory::getApplication();
if($phone && !$plan){
}elseif(!$phone && $plan){
$app->redirect(' 206.217.193.31/~iqcell/index.php?option=...t&view=article&id=18 ');
}

This is what i am using now. and it's going straight to check out after i click add to cart on the phone page..

You should also add the line:
$app->redirect('206.217.193.31/~iqcell/index.php?option=com_content&view=article&id=18');
in the if($phone && !$plan){
otherwise, if the phone is in the cart but not the plan, it goes straight to the cart...

Perfect