Predictive dialers, often used in busy call centers, dial several phone numbers concurrently. To maximize agent productivity, the predictive dialer screens out unanswered calls, busy signals, fax machines, invalid phone numbers, and answering machines. It dials based on a ratio of calls to agents and the number of live connections made. In addition, a predictive dialer optimizes by factoring in the number of available agents, available lines and average call duration. In effect, a predictive dialer works by forecasting when an agent can pick up another call. As a result, it saves agents a substantial amount of time.