| In recent years, the capabilities of telecommunication network have been improved rapidly, and the demands for services have become diversified. To order to attract more subscribers and increase the utilization of network resources, the network operators must provide more services in a flexible manner, which is very difficult based on the closed architecture of traditional telecommunication networks. To solve these problems, the softswitch-based NGN (Next Generation Network) comes into being.NGN is service-driven, it brings up two essential principles—the separation of service from call control and the separation of call control from bearer, which enable us to achieve an open distributed network. When these functions are separated, an open and standardized interface is needed to correlate them implementing various services. Parlay/OSA (Open Service Access) API (Application Programming Interface), is just this kind of bridge which connects call control and services.In this thesis, the way in which telecommunication services are provided is reviewed firstly, and its trend of openness is summarized. Parlay/OSA API is an important turning point in this developing roadmap, which provides a standardized API for service development instead of all kinds of complex telecommunication protocols and makes service development more easily. Since it was proposed by Parlay Group in 1998, it has gained support of organizations such as ETSI (European... |
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