Job interview using a different method.

I just had a phone interview today with a big hospital. I have never done one before. I think I did Ok answering the questions. They said they would let me know something in a couple of weeks, because they had many applicants to interview over the phone. Why do they use phone interviews and what is the process? How do they use the phone interview to select the candidates they want? What is the chance of getting a job through a phone interview? Just wondering. Now I have to wait it out without knowing anything. Thanks.
Phone interviews are useful to narrow down the pool of applicants. I don't believe you will be offered a job based upon a phone interview, but may be called back for a face-to-face meeting with HR and the unit manager.They can be used to identify candidates who have good listening and speaking skills, who present themselves professionally (by using good phone manners, not having background noise, etc.) and who seem to "fit" well with the interviewer. They are quicker to conduct so many more candidates can be screened than with traditional interviews.

You never really know what they want. Just do your best and move on.

The information was helpful. Thanks for your replies.