The Open Service Architecture (OSA) Concept

OSA defines an architecture to enable operators and third-party developers (e.g.,
value-added service providers (VASPs)) to make use of network functionality
through an open standardized interface (called an application programming interface
[API]). It provides applications with access to service capability servers, and
thus provides the “glue” between the applications and the service capabilities of the
network.

In this way, applications become independent of the network. But within the
network, features such as Intelligent Networks and CAMEL provide support for the
required services. The actual applications, however, can be executed in application
servers physically separated from the core network entities. They may be part of the
operator domain, or may be third-party applications. The OSA API is secure and
independent of vendor-specific solutions and programming languages, operating
systems, etc.