Smart phones have brought rapid changes in this competitive world. Smart phone application developers are trying their best to consider the customer requirements in the most efficient way while considering all its attributes. However smart phone service quality has been given less consideration comparatively during the last few years. This paper proposes a measurement method for improving service quality of smart phone application. This method combines the service quality performance model (SQPM) and process capability index (PCI). The service quality performance model is used to identify service items that require improvement. Process capability index is used as a measure for prioritization of those improvements. Case study was carried out to search out important communication application service attributes. customer satisfaction level data was collected for users who used the application service. A total of twenty four service attributes were found during this survey. Using the joint approach of SQPM and PCI, five significant service attributes were prioritized for service quality improvement.