It pays no interest on these bonds. Rather, the bond principal will be returned to bondholders when payments for the pre-sold software come in. The company has stockholders. The stockholders own the company. Restated, the stockholders have a call option on the value of the company's assets.
Stock is a call option on the value of company assets.
Suppose that, because of a declining economy, people begin to renege on their sales contracts. Sure, they've agreed to pay for software, but all the lawyers in hell can't get blood out of a turnip. Let's get out of these bonds, and dump them on some other suckers. But news of the company's problems has leaked out. Maybe the amount of collectible sales is even worse than everyone thinks.