This paper presents a method to examine the effect of introducing data application services on existing wireless CDMA networks where conventional voice communications service is being provided. Since the total number of channels used in a cell is limited in the interfering cellular environments, some voice-traffic channels should be sacrificed when an additional channel is introduced for data services. We investigate this trade-off by analyzing the interference the forward link channels generate. It is also an objective of this paper to examine the forward link capacity in terms of the numbers of paging and voice-/data-traffic channels so as to determine the impact of introducing data services via paging and traffic channels. Different capacity regions are plotted for various cellular environments.