Here's a clue that might prove valuable to your business communication strategy.
When you tell me that it's "only available from Sprint" or "only available on OUR website" or even "not sold in stores," I do not find that a benefit or a value.
It does not increase value to me if you restrict my access to your product or service. Get over it you are not plutonium. So get out in the marketplace, play fair, invite me to do business with you, and if you do a good job or offer a good product, I will come to you.
When you monopolize, you do not gain my loyalty or my business where I can help it!