Paid content website GSM Operator's API Connection

Hi everyone, We have a website and a landing page. We need a help to set up the GSM operator's API. 1. We have a paid content on the website and only users who were subscribed through our landing page should be able to browse it. 2. The landing will be promoted on mobile phones. 3. When the person clicks "subscribe" button and using mobile internet we will get his phone number from the request header and charge his balance. 4. In case if the user not on the mobile phone he can send an sms to subscribe to our service. 5. All the back end processes handled by the API from the operator. We need just setup the API and bring all the subscribers data via JSON file. 6. We need be able to unsubscribe users manually. I will share the API documentation and provide access to the website and landing page with the person I will hire. We have a good documentation and I am expecting to get the results on Monday for a reasonable price. Please apply a bid ONLY if you have experience in similar works.