Wireline-wireless convergence has become an important trend in the telecommunications industry as service providers (SPs) look for ways to increase average revenue per user (ARPU) and continue to reduce their costs. Most SPs believe they can expand their customer base efficiently by offering integrated services that are convenient for end users and that allow them to increase their productivity. SPs with multiple networks also want to eliminate redundancy and further reduce their costs. The emergence of Internet Protocol (IP)-based services, new broadband access technologies, and accessagnostic core architectures made possible by the development of new protocols and based on the IP Multimedia Subsystem (IMS) have created new network and service convergence dynamics that will enable SPs to deliver a broad range of converged services and truly enrich end users' experiences. This paper discusses the convergence opportunities and the key technical challenges and solutions (e.g., intelligent network [IN]/SIP interworking, operations convergence and quality of service [QoS]) that will enable wireline-wireless convergence to become a reality. It also presents a converged network evolution case study for an incumbent SP with separate wireless and wireline networks. © 2005 Lucent Technologies Inc.