ce or 'protocols' to the terminating points. In the modern 'information society' terminals also often appear as a client in a client-server relationship, for example when downloading from the Internet. The terminals Different terminals but the same security requirements and structure Bluetooth terminal GPRS terminal WAP terminal Browsing Secure SAT terminal payment Web browser Voice call SIM with browser and End-to-end security security plug-ins Figure 10.7 Convergence in terminals with transaction service capabilities Terminals communicate with application servers using application protocols. The communication may or may not include interaction. Other relationships are called peer-to-peer and dis- tributive. Napster is an example of a peer-to-peer service (but with network support) and web services are an example of distributed services. The terminal can be equipped with WAP, Bluetooth, cameras, different applications and operating systems. There is in addition a trend towards ad hoc networks, and because of a lack of world- wide standards the conclusion is clear: From being peripheral the terminals become more and more a central point. It seems increasingly tricky to define the capability range of a specific device. Also at the transmission interface there is a need for flexibility. To solve the problem a first step has already been taken with Java, .NET and other program languages. Reconfigurable, downloadable protocol stacks would be a future key enabler for flexible network architecture, allowing an easy adaptation to the application's demands, including radio access (software defined radio). Thus, it ensures a future-proof network architecture, which can keep pace with the application innovation process by changing the mobile station's protocol stacks remotely. The research in this area includes software architectures and an investigation of the hardware impacts. 10.8 WHAT IS A CUSTOMER PREMISES NETWORK? A customer premises network (CPN) is a privately owned network. It is generally managed and controlled b