 for internal communication. A main example is Centrex (centralized ex- change), where all internal communication is handled by the network operator's public switches, instead of an enterprise-owned PABX (private automatic branch exchange) for intra-site communication. In the same way VPNs (virtual private networks) may replace private networks or leased lines when different sites are to be interconnected. Some examples of new roles for service providers are presented in Table 2.1. In some cases a service provider takes on only one role, but in many cases two or more roles are taken on. One example of the latter is the former telecom administrations; that is, the national, government-owned telecom operators that have a long and broad experience from running networks and services although in a monopoly situation. The example list is very dynamic; there is no static truth! Some roles may disappear, many new roles will arise and we will also see a lot of mixtures of roles as long as it promotes business. Understanding Changing Telecommunications - Building a Successful Telecom Business Table 2.1 New roles for service providers Description ASP, HSP Application service provider and hosting service provider. They provide and host services, often physical, but also applications. See also the Role section in Chapter 4. Wireless application service provider is similar to ASP, but for wireless communication (mobile communication). Storage service provider providing storage services for programs and data including back-up services with extremely high safety. Data warehousing may also be offered, i.e. storing and management of data that can be used in the enterprise's business operations or for internal process management. Managed security services provider. Provision of firewalls, intrusion detection and monitoring of access attempts to the enterprise communications network and databases in order to detect and prevent hackers and crackers from access. Internet business service provider. Offers access and hosting of Internet