A predictive dialer dials a list of telephone numbers and connects answered dials to people making calls, often referred to as agents. Predictive dialers use statistical algorithms to minimize the time that agents spend waiting between conversations, while minimizing the occurrence of someone answering when no agent is available.
When dialing numbers one at a time, there are two sources of delay. First, only some fractions of dials are answered. So, for example, if 1 out of 3 dials are answered, a predictive dialer might dial 3 lines every time an agent becomes available. Second, even dials that are answered take some time before being picked up. If it typically takes 10 seconds for someone to pick up, and conversations typically last 90 seconds, a predictive dialer might start dialing at 80 seconds.
Dialing one number at a time, only when an agent is available, typically keeps agents utilized for 40 minutes per hour (33% idle time). Predictive dialing can increase utilization to 57 minutes per hour (5% idle time).