Phone screening interview is the first step in a hiring process. If you fail, you'll never get a chance to proceed to the real interview. Careful preparation is essential and this post will guide you through the preparation process.
Coding Interviews can be hard. Knowing algorithms and data structures is required, but not enough. You need to practice. A lot. Solving problems on your own is a good start, but practicing online with a real person as an interviewer is much better.