Abandoned calls are a side effect of predictive dialing, occuring based on the aggressiveness with which predictive dialing techniques are applied. There is a tradeoff between agent productivity and occurrence of abandoned calls which is generally a major factor in determining agent productivity.

Abandoned calls occur when no live agent is available for a call which is successfully connected to a live person. This typically occurs when predictive dialing techniques provide more live calls than the number of available agents.

An aggressive use of predictive dialing techniques will provide increased agent talk time, but will also increase the occurrence of abandoned calls.

This is easily understood when considering overdialing, one of the more prevalent predictive dialing techniques. Overdialing is the technique of placing more dial attempts than the number of available agents, which compensates for low hit rates (see Hit Rates below). When ten agents are available for a campaign with a 1 in 3 hit rate, the dialer will make more than ten dial attempts.

If 25 attempts are made under this scenario, the dialer will typically provide 8 or 9 calls. If the hit rate were stable around 1 in 3, the dialer would usually provide 7 to 10 calls, and only occasionally 11. This approach would typically require additional dial attempts for up to 3 agents, who would then remain idle during these additional dial attempts. However, it would only produce a small amount of abandoned calls.

However, if 35 attempts are made under the same scenario, the dialer will typically provide 11 or 12 calls. If the hit rate were stable at 1 in 3, the dialer would usually provide 10 to 13 calls, and only occasionally require additional dial attempts to provide calls for all 10 agents. While this approach would provide much better agent talk times, it would also produce a steady flow of abandoned calls.

While this example illustrates the underlying tradeoff, it does over-simplify things a bit. In the real world, hit rates do vary, dialers typically use other techniques as well, and agents actually come available as they complete calls rather than in groups of 10.

The key takeaway is that there is a tradeoff, and there are diminishing returns on either end of the continuum between maximizing agent productivity and minimizing abandoned calls. In the example above, there would be little difference in abandoned calls if making 12 dial attempts rather than 20, but a huge difference in productivity. Likewise, there would be little difference in productivity if making 60 dial attempts rather than 45, but a huge difference in abandoned calls. A good predictive algorithm will be able to achieve high levels of agent talk time, with a minimum of abandoned calls. Most dialers will also provide options for directly or indirectly controlling how aggressively the predictive dialing techniques are applied.

The State of California recently established regulations which restrict abandoned calls. These regulations are likely to present a challenge to outbound operations which place calls to California's residential households, and have led to speculation that similar regulations might also be enacted by other states, and possibly at a national level. The FTC has more recently followed suit with adoption of similar regulations restricting abandoned calls to a maximum of 3%.

Predictive Dialers
Predictive dialers generally abandon calls for which no agent is available.  This typically occurs after allowing a brief period of time for an agent to become available.  The exact processing depends on the dialer, and how it has been configured.

1. Predictive dialing algorithms are generally fairly sophisticated in their details, to substantially increase agent productivity without excessive amounts of abandoned calls.  You should recognize a number of key points about predictive dialing and abandoned calls.1. A greater use of predictive dialing techniques will provide increased agent productivity (typically measured in terms of agent talk time per hour), but will also increase the occurrence of abandoned calls.  A good predictive algorithm will be able to achieve high levels of agent talk time, with a minimum of abandoned calls.  Most dialers will also provide options for directly or indirectly controlling how aggressively the predictive dialing techniques are applied.
2. Dialers typically support other pacing algorithms such as preview dialing and power dialing.  When considering a dialer, it's important to understand what these pacing algorithms actually mean for that particular dialer, as the meaning, techniques, and control options are often different from dialer to dialer.  For example, in some circles, powering dialing means dialing out on all available circuits to achieve the absolute maximum in agent productivity. This technique typically generates a very large amount of abandoned calls.