In tactical missions, seamless and effective communication is crucial for mission success. For future deployed networks, the user experience can be improved with proper resource allocation mechanisms, taking into consideration quality of service characteristics of the traffic. Such a resource allocation method requires knowledge of the key performance indicators of the communication path. In this article, we present a framework for the key performance indicator estimation service for deployed heterogeneous networks. Our proposal utilizes several different approaches for measuring key performance indicators. Several mechanisms are used to improve the accuracy and reliability of the service. We also discuss the lessons learned during the key performance indicator estimation service implementation and the validation process.