A call center includes a plurality of agent workstations, each agent workstation comprising means for entering information obtained from a telephone respondent in response to questions prompted by a script displayed on the display of the workstation, and means for producing status signals indicative of the progression of the agent through the script. A predictive dialling system receives status signals from each agent station and predicts from the status signals and statistical information regarding the number of calls previously made, how many new calls should be dialled to enable agents who have finished their previous call by the time the calls are answered to take the new calls.