I wrote about salaries in job descriptions on another blog. However, if there isn't a range published, I usually ask about the range in the initial phone screen.
I'll ask early, usually once I get an idea of what the job entails. The reason is that I don't want to waste my time or theirs. If the salary is too low, there's no point in continuing. I have asked if there is flexibility, and sometimes there is, but often there isn't.
At the same time, I don't disclose my current salary. It's not relevant. They're hiring me to do their job, at the rate they think is appropriate. It doesn't matter what the last person paid me, since it could be way out of scale (either way) for my skillset.
Have confidence when you apply for a job, and expect to be paid what anyone else would be paid to do that job, within the range the company has set.
