The goal of the universal mobile telecommunications system (UMTS) is to deliver multimedia services to the user in the mobile domain. UMTS and multimedia services have a significant impact not only on the radio frequency (RF) network, but also on the core network architecture. Care must be taken to allow current global system mobile (GSM) operators to protect their infrastructure investments when their networks are upgraded to support UMTS. We discuss our unique experiences on design and deployment of more than thousand UMTS sites in US and Europe. This presentation focuses on the implications and difficulties in integrating current cellular networks with UMTS radio system planning. We discuss the challenges on both RF planning and Internet core network planning. The path to All-IP migration is presented.