This Recommendation specifies the interaction between BICC and INAP CS-4. It also specifies ISUP/INAP CS-4 interaction procedures as exceptions to BICC/INAP interaction procedures (see Annex B). For the purpose of this Recommendation the interface INAP CS-4 between SSP and SCP is regarded as being an intra-network interface. The interaction between other signalling systems and INAP can be found by consulting the relevant interaction Recommendation to BICC in combination with this Recommendation. This Recommendation specifies procedures in order to provide interaction between BICC and INAP, i.e. to support IN services in an ISDN environment. In addition, new protocol elements for the BICC are defined in this Recommendation in order to satisfy IN specific requirements. Based on the protocol inherent compatibility mechanism, a stepwise upgrade of the BICC functionality is possible. However, the new function is only available for an IN call, if supported in any of the affected service nodes. In this Recommendation the IN SSF is treated as a functional part of the BICC CSF (see Figure 2). It is presupposed that this functional inclusion of the SSF has no impact on the CSF/BIWF interface. Any such impact is out of the scope of this Recommendation. This Recommendation describes SSF/CSF interaction only on "transit" level, i.e. no special further interworking is described for CSF-Ns with incoming/outgoing call control signalling to access networks (i.e. ISN to ACN-E/TE call control relationships). As a consequence, specific accessrelated interaction (e.g. interaction of line based triggering with ISDN supplementary services) is not within the scope of this Recommendation. This Recommendation therefore, also does not specify enhancements to the call control protocols at the access network level (e.g. DSS1), which may be needed due to additional BICC functions or IN requirements, respectively. This Recommendation therefore, also does not specify enhancements to the call control protocols at the access network level (e.g. DSS1), which may be needed due to additional BICC functions or IN requirements, respectively. The main subjects of this interaction Recommendation are the following: description of specific call control functions for IN calls; impacts on the BICC basic call setup and the ISDN supplementary services for IN calls; and of the BICC protocol due to IN specific requirements.