The present document specifies the interaction between the ISUP and INAP.
The interaction between other signalling systems and INAP can be found by consulting the relevant interworking
recommendation to the ISUP in combination with the ISUP/INAP interaction recommendation.
The present document specifies procedures in order to provide interaction between ISUP and INAP, i.e. to support IN
services in an ISDN environment. In addition new protocol elements for the ISUP are defined in order to satisfy IN
specific requirements. Based on the protocol inherent compatibility mechanism a stepwise upgrade of the ISUP
functionality is possible. However, the new function is only available for an IN call, if supported in any of the affected
exchanges.
The present document only considers the case where the SSP is located at a transit level. As a consequence this could
lead to limitations for ISDN supplementary services.
The present document does not specify enhancements to the DSS1 protocol, which may be needed due to additional
ISUP functions or IN requirements, respectively.
The main subjects of this interaction specification are the following:
- description of specific call control functions for IN calls;
- impacts on the ISUP basic call and the ISDN supplementary services for IN calls;
- enhancement of the ISUP protocol due to IN specific requirements.