Some hints that helped me a lot:
- 2 calls is nothing. 100 calls is something. Do 100 calls. 50 at least.
- Step by step. Step from call to purchase is too large. Make it shorter - appoint the meeting. Let the meeting be the objective of your call.
- Are people you call the ones to make final desicion at the company? If not - you miss the point. As for your product - you need marketing director or CEO. Reach them.
- At the meeting - don't talk about features of your product - talk about benefits your product will bring this person.
- Have something to show - better business cases. Your cases are the best, off course. But any will do. There are plenty of stories when mobile websites made business grow. Just have something the client could look and feel.