We consider the consequences of introducing a component-based architeture in a large real-time telecommunication system. The goal is to decrease the cost for software maintenance while preserving existing performance levels. We have developed a component-based prototype and compared this new architecture with the existing system architecture. Two aspects have been evaluated, viz. maintainability and performance. The evaluation indicated that the maintainability cost was reduced with approximately 20%. There was a marginal performance degredation when using one CPU in the component-based architecture. The component-based architecture was, however, more efficient when using a multiprocessor.