We can build extension for send sms for all costumer with option to disable / enable for every costumer.
Will provide opption to disable from link
Relevant Skills and Experience
PHP (Cake PHP, Core PHP), WordPress, Magento, Joomla, Ecommerce, JavaScript, Codeignitor, Zend Framework, HTML (4.0 & 5.0), CSS (2.0 & 3.0) and Open Cart along with impressive design.
Proposed Milestones
$277 USD - 5Days
please allow me for share Opencart Sample at Pm,
Best Regards
Binod