The transition from second- to third-generation mobile systems and the evolution paths of the relevant radio/network configurations are driven by technical and market considerations. In fact, these are affecting the standardization and research process ongoing at the regional level (ETSI, ACTS Program, US Joint Technical Committee, Japanese ARIB) as well as the global level (ITU). The related discussion is becoming more and more meaningful for operators and manufacturers who are perceiving, on the one hand, the new perspectives associated with service, features, and bandwidth management evolution, and on the other hand, the great impact that such an evolution could have on the existing market scenario and system development plans. In addition, due to the widespread usage of GSM worldwide, this system should also be considered within the evolution scenarios toward third generation. This paper analyzes the situation emerging from the standards context, identifies some key characteristics associated with current proposals, and tries to define a possible third-generation systems architecture based on the most encouraging propositions, e.g., the separation of radio-dependent and independent functions and the integration with B-ISDN. The paper rationale and the identified solutions reflect the research activities within the ACTS project RAINBOW (radio access independent broad band on wireless), addressing architectural solutions for UMTS (universal mobile telecommunications system), the European developing standard for third-generation systems.