Have a general understanding of the company, such as what they do, industry, possible competitors. Read, understand, and bring a company of job description to the call.
Familiarize yourself with current industry buzzwords, metrics and standards. Being able to articulate your answers from an industry-wide perspective will help to show your potential value as an employee.
Be able to tell a cohesive story about your professional experience. When telling your story, it is important to be positive when discussing previous employers and explanations for any potential gaps in work history.
Asking engaging questions can go a long way, not just to know if this is the right opportunity for you, but also to show the interviewer that you are a capable thinker and you've invested time in preparing for the interview.
Don't let issues with technology get in the way of your next job. Being in a place with a strong phone signal, minimal noise and limited distractions will let the interviewer focus on you.