A predictive dialer dials a list of telephone numbers and connects only the answered calls to agents. Predictive dialers use statistical algorithms to minimize the time that agents spend waiting between calls and ringing time on a dialled call, while minimizing the occurrence of someone answering when no agent is available.
Refer the image above of a 80 seat callcentre with 8 PRI Lines(240 active channels) as its telecom resource. The customer is KLR Global an Airtel outbound callcentre. They start calling from 10:30 and close at 6:30 with 30 minutes lunch for callers. This report was taken @ 4:56 PM with about 6 hrs of active calling on the given day. The data inference is as follows.
To conclude, to achieve a productivity of 400 calls per agent in a 8 hour shift, you need to have a database with at least 40% call maturity and an agent to telecom channel ratio of minimum of 1:3
To conclude, it is clear that predictive mode of dialing achieves 4 times the productivity @ 15% additional investment per month over manual while progressive mode of dialing achieves 2.5 times the productivity @ 5% additional investment per month.
To conclude, it is better to invest on dialer either on rental or outright to achieve the best per call rate. The difference is too large to ignore and to continue ignoring must have an element of insanity than any logical reasoning.