As part of the hiring process you may be asked to participate in a Phone interview. These interviews are much shorter than in-person interviews and are mainly used to screen people out of the possible pool of candidates, and end up with a smaller list of people to invite for the in-person interviews.
The phone interview gives you the advantage of having your resume, job description and any other documents to hand, and since they cannot see you, you can wear what you want and, providing there are no distractions or noises to interfere with the call, you can take the call any place you want.
Since the interviewer cannot see you or your body language, they are more attuned to what you’re saying and how you say it. This means your answers need to be concise and said in a way that the interviewer can easily understand, while giving them a sense of your level of professionalism and passion for the job.
Make sure you treat the phone interview as importantly as the in-person interview, you can be screened out at either stage.