Dialing number after number to find that one person who might be willing to listen to your sales pitch is time consuming enough without having to deal with answering machines and disconnected numbers. Using a predictive dialer to check out these random numbers first can save a lot of time and frustration as it lets workers concentrate on other things instead of sitting in front of a phone book, hoping the next person listed has not ended his or her telephone service. Instead, humans can go off and do whatever else they need to do, while the predictive dialer runs through all of the numbers its been given. When someone actually picks up a line, the dialer will alert a nearby human.
Using these dialers not only reduces the number of staff needed to work the phones — an advantage for companies squeezed into small office spaces — but also increases the amount of time the workers have to take care of other office tasks. If the office is full of telemarketers, they can hold actual conversations with potential customers instead of rushing through them, trying to make a sale before going back to dial yet more numbers and wait for another person to pick up their phone line.