Rec. ITU-T X.31 (03/1993) SUPPPORT OF PACKET MODE TERMINAL EQUIPMENT BY AN ISDN
FOREWORD
CONTENTS
1 General service aspects
2 Reference configurations
    2.1 Configuration when accessing PSPDN services (Case A)
    2.2 Configuration for the ISDN virtual circuit service (Case B)
3 Service aspects
    3.1 Access to PSPDN services (Case A)
        3.1.1 Service characteristics
        3.1.2 User access capabilites
        3.1.3 Basic rules
        3.1.4 Notification classes
    3.2 Access to the ISDN virtual circuit service (Case B)
        3.2.1 Service characteristics
        3.2.2 User access capabilities
        3.2.3 Notification classes for X.25 incoming calls
    3.3 Compatibility checking
4 Addressing and routing aspects
    4.1 Terminal interface selection
        4.1.1 Terminal interface selection by means of MSN/DDI
        4.1.2 Terminal interface selection by means of ISDN subaddressing
    4.2 Access to PSPDN services (Case A)
        4.2.1 Channel type selection
        4.2.2 Addressing scheme for outgoing calls
    4.3 Access to the ISDN virtual circuit service (Case B)
        4.3.1 Channel type selection
        4.3.2 Addressing scheme for outgoing calls
5. Interworking with dedicated networks
    5.1 Circuit-mode access to PSPDN services (Case A)
    5.2 Access to PSPDNs via virtual circuit service (Case B)
6 Packet communications at the S/T reference point
    6.1 Outgoing access
        6.1.1 Circuit-switched access to PSPDN services (Case A)
        6.1.2 Access to the ISDN virtual circuit service (Case B)
    6.2 Incoming access
        6.2.1 Access from PSPDN services (Case A)
        6.2.2 Access from the ISDN virtual circuit service (Case B)
    6.3 X.25 Virtual call establishment and release
        6.3.1 Link layer establishment and release
        6.3.2 Packet layer virtual call setup and release
    6.4 Call clearing
        6.4.1 B-Channel
        6.4.2 D-Channel
        6.4.3 Additional error handling information
        6.4.4 Cause mappings
    6.5 Access collision
7 Terminal adaptor functionalities
    7.1 General
    7.2 Physical interfaces
    7.3 Access through the B-channel
        7.3.1 General
        7.3.2 Rate adaption
        7.3.3 Signalling
        7.3.4 Synchronization
    7.4 Access through the D-channel
        7.4.1 General
        7.4.2 LAPB-LAPD mapping
        7.4.3 Signalling
    7.5 Access through the B and D channels
        7.5.1 General
        7.5.2 X.25 outgoing call
        7.5.3 X.25 Incoming call
    7.6 Test loops
        7.6.1 Test loops for TA with access through the B-channel
        7.6.2 Test loops for TA with access through the D-channel
Appendix I B-channel TA acting on layer 2 and 3 of X.25
I.1 Introduction
I.2 Call control
I.2.1 Idle phase
I.2.2 Establishment phase
I.2.3 Data transfer phase
I.2.4 Clearing phase
Appendix II Interconnection of packet mode TE2s which use the circuit-mode bearer ...
Appendix III Example message flow diagrams and example conditions for cause mapping
III.1 Example message flow diagrams
III.1.1 Key to the figures
III.1.2 Example message flow diagrams
III.2 Example conditions for cause mapping
Appendix IV D-channel TAs requiring full protocol termination in the TA
IV.1 Introduction
IV.2 Call control
IV.2.1 Idle phase
IV.2.2 Establishment phase
IV.2.3 Data transfer phase
IV.2.4 Clearing phase
Appendix V References