Coupons can only be used when a customer subscribes through your subscription page. When a customer is activated manually, a discount coupon code cannot be added. The customer's invoice is also not processed through your payment gateway. In other words, by activating the customer manually, the system will not be able to charge them automatically. As an operator, you are charged for the cost of the phone service and you can charge the customer outside of the SphereMail platform manually.