 information about the subscriber that is available in the home location register (HLR) or mobile positioning centre (MPC) the information can be tailored to the subscriber position. The HLR knows the cell where the subscriber is located. The MPC can give even more exact positioning when equipped with GPS, and can also provide geo-navigational services. Messaging functions for MMS and other messaging services is another added value. Understanding Changing Telecommunications - Building a Successful Telecom Business Video playback can also be regarded as a value-added content service. For a business user who can access the same information from many devices a syn- chronization service is appreciated. Imagine a business user who owns a mobile phone, a PDA, a laptop computer, and a desktop PC. Assume that it is possible to perform an update to a contact's phone number stored on the mobile phone, and that this update would be transmitted to other devices and databases. This broad update could include a contact list on the PDA, a contact list within Outlook on the laptop and desktop PC, a corporate CRM database, and potentially an Internet-based calendar and contact list that the user might occasionally access. The need for keeping this data in sync with the other data sources is an absolute requirement in order for the devices to be of their greatest value, and for the user to work efficiently. 5.6 ECONOMY OF SERVICE BY MEANS OF CACHING A new dimension in network design is introduced by content-based networks. In order to save capacity in the network modern cache systems can be used. Caching is a type of middleware function. When surfing you often don't know the location of the 'B-subscriber' (the source). The content can be web pages, e-business, bank services, streaming video, broadcasting etc. Considering the traffic load the source should be as close as possible to the surfer. Such source could be an intermediate cache-type storage in a mirror server at the edge of the network. In order to perform intermediate sto