If they don’t get an answer, they won’t call back.
Cell phones are notorious for going in and out of service.  If the employers calls and doesn’t receive an answer, chances are hey are not going to call you back – and you’ve missed a career opportunity.
Cell phones are not 100% reliable.   Use a landline if at all possible.

Find a quiet place with no distractions.
If you’ve got a noisy household, you can quickly be distracted by things going on around you.  You’ll need to be at the top of your game during this interview – if need be, drive to a parking lot and sit in your car for the duration of the interview.

Be prepared.
Put your resume, job description, company information in front of you as a reference if needed.  Don’t get caught off guard when they ask a question about your prior experience.

Be professional.
Maintain professionalism throughout the interview – remember: they cannot see your facial expressions, they may not know when you are joking.  So don’t!

Do your research.
Research the company – PREPARE!!!  Have a few good questions for the interviewer ready in advance.