CONTENTS

 1     Introdution
 2     Scope
 3     Required information and information handling
 4     Description of ISDN-ISDN interworking configurations
        4.1     ISDN-ISDN interface where circuit mode bearer services are provided by both ISDNs
        4.2     ISDN-ISDN Interface where both ISDNs provide X.31 case B based packet mode bearer services           
        4.3     ISDN-ISDN interface where a circuit mode bearer service is provided by one ISDN to access either a PSPDN, or a PH and an X.31 case B packet mode bearer service provided by another ISDN
        4.4     ISDN-ISDN interworking via a transit network
        4.5     ISDN-ISDN interface for additional packet mode bearer services
        4.6     ISDN-ISDN interface where an X.31 case B based packet mode bearer service is provided on one ISDN and an additional packet mode bearer service is requested on another ISDN
        4.7     ISDN-ISDN interface for circuit mode to additional packet mode service
 5     Interworking functions
        5.1     Echo control processing and speech processing
        5.2     Generation of in-band tones and announcements for speech and 3.1 kHz audio bearer services
        5.3     Call negotiation between ISDNs
        5.4     Compatibility checking between end users of different ISDNs
 6     Functional interworking requirements for data transmission services
 7     References
Appendix I – ISDN connections involving restricted 64 kbit/s transfer capability
        I.1     General
        I.2     Interworking with ISDNs providing restricted 64 kbit/s
        1.3     Considerations for terminal designed to operate with restricted 64 kbit/s transfer capability