- unacceptable for general network planning purposes. Voice and pictures must be fully synchronized in video conversations. This means that the above values are also valid for the picture component. Delay variation - none (as perceived by the user). Buffer functions at the receiver side can handle smaller delay variations, but the delay, as described above, increases. Noise - none/low. Service accessibility - no or low congestion is the adequate measure in circuit-switched networks. In packet-oriented networks the effective throughput, measured in bit/s is a more adequate measure (to avoid 'slow' connections). Service availability - high, meaning no or low probability of interruptions of the ser- vice. Bit error ratio (BER) - low or medium depending on application. 5.4.2 STREAMING CLASS Multimedia streaming is a technique used for transferring information such that it can be processed as a steady and continuous stream. Streaming technologies are becoming Understanding Changing Telecommunications - Building a Successful Telecom Business increasingly important with the growth of the Internet because most users do not have fast enough access to download large multimedia files quickly. Typical users of the streaming class are streaming real-time applications, for example audio/video retrieval: streaming audio (news, music etc.) streaming video (news, music, traffic information etc.) With streaming, the client browser or plug-in can start displaying the data before the entire file has been transmitted. For streaming to work, the client side receiving the data must be able to collect the data and send it as a steady stream to the application that is processing the data and converting it to sound or pictures. Streaming applications are very asymmetric and therefore they withstand more delay than the more symmetric conversational services. This also means that they tolerate more jitter in the transmission. Jitter can easily be smoothed out by buffering. Streaming and downloading are compared in Figure 5.8. Streaming offe