In this letter, we obtain the outage probability for DS-CDMA-based air interface in the presence of traffic with heavy-tail distribution of call durations. Obtained results show that the outage performance for a given wireless network designed based on the Poisson assumptions is significantly degraded when the actual traffic has heavy-tail distribution of call durations. Degradation in outage performance results in a lower traffic capacity. It is also shown that the performance degradation is higher for distributions with heavier tail.