 the demands of highly-available core networks. Intel, Novell, and IBM have all invested heavily in Linux and Linux-powered core solutions and in Java-based client solutions, leveraging the strength and cost-effectiveness of Linux in the core and Java's ubiquity and flexibility on diverse and rapidly evolving clients. In many ways, Java is the programming language for distributed network applications that leverage Internet connectivity. THE NETWORK The Internet The Internet is the preferred application network for allowing mobile devices to access rich multimedia content and interactive services such as video conferencing, IM and other presence-based services. In 1999, VON (Voice On the interNet) advocate Jeff Pulver accurately asserted, "It will be the technologies surrounding instant messaging and presence management that will be the true killer app for service providers who have invested in IP based communication networks." IP based technologies, applications and services have fostered new generations of mobile, handheld devices because they provide unique solutions that the public demands. One can already drag-and-drop a voice or video message into a task list on a PDA, and voice-to-text conversion is simply a matter of accessing a server-based unified messaging (UM) application. Instant messaging, unified messaging, and presence management will increasingly justify the investments that service providers make in IP networks. Carrier trunking switches are already relying upon SIP (session initiation protocol), which is quickly displacing H.323. IP networks offer integrated SS7 functionality, and allow carriers to supplant circuit-switch networks with MPLS-based, QoS rich, application-integrated IP networks. Wireless Carrier Networks Evolve In the past, the term Wireless Carrier Network might have simply represented a provider of cellular-based network telephony services (and limited data options). Today, data is the market driver, with most carriers now offer a host of high-speed data and even The Future of Vi