Ecommerce site

Please read this carefully I have a client who would like an e-commerce site built using the likes of ECT (look up ECT in google) this site is for ebooks he wants the site to go through the normal process of purchase but when it gets to the payment page we want to offer two modes of payment 1. Paypal 2. SMS. I have the ECT software which I will supply to the right person so you have no software costs all I really want you to do is make the software work on the server with a simple design and also implement the SMS payment method on the payment /cart page.

GUYS I HAVE ALREADY HAD A LOT OF EMAILS AND NOT ONE PERSON HAS MENTIONED HOW THEY WOULD MAKE THE SITE WORK WITH SMS PAYMENTS THIS IS EXACTLY WHAT I NEED. IF THE ECT SOFTWARE CAN'T DO IT SHOW ME A SOLUTION THAT CAN AND NOT JOOMLA OR MAGENTO