are unable to interpret con- catenated messages that are part text and part binary. It is also quite difficult to cre- ate EMS messages on small handsets. On the other hand, they are rather easy to cre- ate on the Internet, and some people download images or sounds and send them to their friends. EMS is a step on the path to MMS. MMS, the multimedia message service, is under development as part of the 3G stan- dard. It can be implemented on some 2.5G networks, and one existing service, Japan's i-mode service, offers functionality similar to MMS. MMS replaces the SMSC with a multimedia message switching center (MMSC), which is IP-based. It supports a wide variety of graphic and audio formats and can handle graphic resizing and audio com- pression to create compatibility across different user terminals. As the MMS standard develops, there is a very strong effort to make it compliant with a wide range of exist- ing and forthcoming standards for Internet, multimedia, and home services. The result is that all kinds of still images and sounds and, when the higher-speed data rates are in place, perhaps even moving images will be available on cellular telephones, on the Internet, and on all kinds of other devices as well. What is the concept behind such a major development effort? Proponents of MMS make the analogy to the shift from DOS-based personal computers to Microsoft Win- dows. They argue that the entire world of personal computing changed when the per- sonal computer became able to handle graphics and that screen savers were popular and profitable software packages. MMS proponents think that MMS can do for cellular telephones what Windows and the After Dark screen saver did for the personal com- puter. This may be true, but it may be the wrong analogy. The personal computer worked primarily with printed documents, where adding pictures and text formatting to plain text made a big difference. Screen savers sold well as a novelty item for a while, but eventually they became free giveaways included in Windows. The r