Movie clips News (video with voice) Music listening Slideshow (images with voice) Animated advertisements Voice/audio with text or images Bit rate kbit/s File size kBytes/30s Figure 5.15 Bit rate demands and storage requirements for on-demand mobile services Conversational voice services including IP telephony at around 10 kbit/s. Conversational video telephony from around 64 kbit/s to more than 1 Mbit/s. Interactive browsing/downloads around say 100 kbit/s with a broad spectrum up and down. WAP browsing contains significantly fewer bytes and can therefore use a nar- rower bandwidth. Understanding Changing Telecommunications - Building a Successful Telecom Business Interactive multimedia browsing around say 300 kbit/s with a broad spectrum up and down. Interactive gaming around say 300 kbit/s with a broad spectrum up and down. Streaming music around 50-200 kbit/s. Streaming in general according to Figure 5.15. Background 'any' speeds. Background accepts what is offered. Messaging e-mail text about 30 kbit/s but down to 9.6 kbit/s is possible. With multi- media the requirements are much higher. Transactional services 'any' speeds, since focus is not speed, but security and accuracy. Many services are possible at quite a low bit rate around 10 kbit/s. One reason is WAP, another one is the Japanese I-mode system. The maximum speed for I-mode download is 28.8 kbit/s for top range models, and 9.6 kbit/s for standard handset models for 2G I-mode services and in the order of 200 kbit/s for 3G services. 9.6 kbit/s is sufficient for simple I-mode data. Of course this speed makes it impossible to download live movies through I-mode. I-mode on 3G is much quicker: it permits 384 kbit/s download (typically 200 kbit/s) and 64 kbit/s upload in best conditions and therefore allows video telephony. 5.9 SECURITY Security has developed to become a vast area. A lot of security improvement measures can be done outside the network, for example in the operating system of the terminals Authorities for encryption key handling and authori