This invention relates to a supplementary services layer (SSL) application in
the switching node for the development and execution of subscriber-based supplementary
services. The SSL communicates with the L4 application through an L4-L5 interface.
Therefore, a system operator may configure the switching node to execute supplementary
services without intervention from a host application and without modification
to the current L4 application. The SSL also communicates with the L5 application
in order for that application to integrate supplementary services without further
modifications. The SSL comprises a Database Interface Service, a Service Object
Manager (SOM) and one or more instances of a Supplementary Service Object (SSO).
The database interface service provides connection to an external database which
stores each subscriber's profile. Each SSO instance implements one or more supplementary
services for a call. The SOM exercises overall control over these SSO instances.
