f messaging are also of interest for these customers, e.g. SMS, especially to a younger group since they have limited possibilities for investing in a feature phone but may still want the 'chat' type of communication they have on the Internet. WAP is fully supported and Bluetooth is considered to further enhance the voice capability as well as improving the messaging services. 10.5 PDA DEVELOPMENT A typical range of functions in a personal digital assistant (PDA) may be mobile phone, music, calendar, GPS positioning, SMS-EMS-MMS messaging, WWW, camera, voice recognition, translation, digital wallet, and possibly TV and/or printer. Understanding Changing Telecommunications - Building a Successful Telecom Business 10.6 TERMINAL CONVERGENCE Convergence in terminal capabilities is prevalent for most services. For mobile devices we have the grouping into wireless Internet and mobile media. Starting with Internet WWW services we may find such capability in 'everything' from PDAs to desktop machines to laptops to WAP phones to phone browsers to web television units to specialized browsers for users with disabilities. We see that the 'web terminals' can also be used as media terminals, such as streaming video services in the mobile terminal. A new word is 'wearables'. The idea behind wearables is to design gadgets out of simple electronic components in place of 'computers'. Thus, wearable computers can be seen as propagations of the human senses. Terminal convergence can also be viewed for transactional services. See Figure 10.7. Some trends point at terminal interworking and roaming between different technolo- gies such as UMTS and WLAN. Roaming GSM-UMTS is already established. Different deployment alternatives for the two radio interfaces may appear on the marketplace: separated terminals for different radio interfaces and multi-mode terminals, whereby multi- mode terminals integrate both cellular radio interface and WLAN into one physical device. The user subscriber information, which is stored on the USIM, needs to b