This paper describes the prediction and evaluation of the call‐processing capacity and reliability resulting from use of the 3B20 Duplex (3B20D) Processor in the Traffic Service Position System No. IB (TSPS No. IB). The call‐processing capacity was predicted using a processor real‐time model whose parameter values were determined by laboratory and test‐site measurements. The system reliability was predicted using Markov modeling techniques. Performing an evaluation during TSPS No. IB development provided a means for monitoring progress toward meeting the capacity and reliability objectives.