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A simpler way of doing this is to become an affilite for one of the existing providers. Some providers will allow you to set up your own premium SMS number for your order codes to be sent, you can then provide your own number and tey provide product codes. You can them develop your own site and provide your users with the correct code per product.
If I where you I would start very small. Create a mobile site offering info and reviews with affiliate links then if/when traffic gets high enough you can branch of into the market you mentioned. I do not have any involvment in the mobile market, but it will be a very competative space to try and get a foot in the door.
Workign with a provider means less outlay, and perhaps larger margins?
You dont make as much, but you dont spend anywhere near as much.