CONTENTS

 1     Scope
        1.1     General
        1.2     Use of bearer capabilities
        1.3     Protocol architecture
 2     ISDN B-channel circuit-switched mode (DTE-DTE communication)
        2.1     Protocol set
        2.2     Application rules
 3     ISDN B-channel packet-switched mode (DTE-DCE communication)
        3.1     Protocol set
        3.2     Application rules
 4     Support of the OSI-network service
        4.1     Rationale for considering the OSI-NS
        4.2     CCITT Recommendations and ISO standards
        4.3     Requirements for the OSI-NS
 5     Additional X.25 optional user facilities
        5.1     Categories of additional functions
        5.2     Functions

 6     Interactions between the D-channel and B-channel
 7     Supplementary services
 8     Terminal response time
 9     Synchronization
10     Higher layer protocols
       10.1     Group 4 facsimile
       10.2     Teletex
       10.3     Videotex
Annex A     –      Procedures for connection establishment, connection release and information transfer
Annex B     –      ISDN D-channel packet-switched mode (DTE-DCE communication)
Annex C     –      Procedures for B-channel negotiation of layer 2 parameters for telematic terminals
Annex D     –      SDL diagram for link set up for SABM/SABME procedures
Annex E     –      SDL diagram for link set up to a T.90 compatible terminal for XID procedure
Appendix I     –  Facsimile terminals in the ISDN
Appendix II–     Optional usage of the T.70 NL protocol
Appendix III     –      Service definitions and state transition diagrams for the data link layer within the B-channel (CS mode)
Appendix IV–     Possible model for telematic endsystems taking into account the D-channel/B-channel coordination function
Appendix V–     Rate adaptation function
Appendix VI–     Recommended combinations of parameter values to ensure optimum throughput
Appendix VII     –     Alphabetical list of abbreviations.