Abstract: In this study, an adaptable Turbo codec has been designed to meet the specifications of different Quality of service (QOS) of 3G applications. In the third generation networks, a wide variety of services are offered and the different services require reconfiguration of the existing Turbo codec. There are different stages involved in the design of turbo codes. The design varies according to the requirements of quality of service. Certain applications may require less delay, whereas some other application may need less loss in data. Turbo codes can be made to satisfy the different QOS requirements by proper analysis and design. In this study, a complete analysis has been made on certain QOS requirements and the impact of various components of turbo codes on the QOS. Based on the analysis alongwith the simulation, the design of turbo code is implemented to achieve the desired Quality of service for various transmission.