The signaling interface is a library of C language subroutines and a set of primitive definitions that enable you to add support for new common channel and exchange data link signaling protocols to Blueworx Voice Response. The programming model for the signaling interface is based on the OSI reference model (X.200), and involves the exchange of primitives between Blueworx Voice Response and the signaling process. The names of the signaling interface subroutines all start sl_ and are defined in Signaling interface subroutines. The names of the primitives all start SL_ and are defined in Signaling interface primitives.