A significant development took place in the recent period on the intelligent network services market. There is an ever-increasing demand for customized solutions as the number of clients increases. It can happen that a certain service might be interesting to a narrow selection of clients only – sometimes one or two clients only. Another current market trend is the increase of expectations for convergent solutions encompassing the three areas of telecommunications. By connecting landline, mobile and internet services such unified communication might be realized where office/home landline and mobile communication possibilities complement each other. Earlier, telecommunications service providers developed their new network services in a closed development environment, which were not cost-effective except when a larger number of customers were present, and prevented the establishment of convergent solutions. The recently established Java platform is a flexible and standard solution, simplifying the service establishment process. Using this platform enables the profitable establishment of services with a limited number of customers. A SIP-based (IP Multimedia Subsystem compatible) system is created, which supports the creation of unified voice, data and multimedia communications services based on an IP-network.