1     Scope
 2     References
 3     Definitions
 4     Electrical and physical interface requirements
 5     Procedural interface requirements
 6     Services and architecture aspects and requirements
        6.1     On-demand services
                  6.1.1     PSTN
                  6.1.2     ISDN basic access
        6.2     Permanent Line (PL) capability
        6.3     Semi-permanent leased line
        6.4     Permanent leased line services
 7     Control and provisioning
        7.1     Control principles
                  7.1.1     General requirements and assumptions
                  7.1.2     Control of ISDN user port for the PL capability
        7.2     Provisioning strategy and requirements
                  7.2.1     General
                  7.2.2     Provisioning requirements
 8     Protocol architecture and multiplexing structure
        8.1     Functional description
        8.2     Protocol requirements for PSTN and ISDN
        8.3     Time slots
        8.4     Time slot allocation for communication channels
        8.5     Layer 2 sublayering and multiplexing on communication channels
        8.6     Layer 3 multiplexing
        8.7     Congestion control
                  8.7.1     Flow control end to end
                  8.7.2     Congestion control on the V5.1 interface
                  8.7.3     Blocking of ISDN user ports at layer 2
                  8.7.4     Flow control using LAPV5-DL mechanisms
 9     Envelope Function Sublayer of LAPV5 (LAPV5-EF)
        9.1     Frame structure for peer-to-peer communication
                  9.1.1     General
                  9.1.2     Flag sequence
                  9.1.3     Interframe time fill
                  9.1.4     Envelope function address field
                  9.1.5    Envelope information field
                  9.1.6     Transparency
                  9.1.7     Frame check sequence (FCS)
                  9.1.8     Format convention
                  9.1.9     Invalid frames
                 9.1.10     Frame aborts
        9.2     Format of fields for data link envelope peer-to-peer communication
                  9.2.1     Envelope function address field format
                  9.2.2     Address field variables
10     Data link sublayer of LAPV5 (LAPV5-DL)
       10.1     Frame structure for peer-to-peer communication
                 10.1.1     General
                 10.1.2     Link address field
                 10.1.3     Control field
                 10.1.4     Information field
                 10.1.5     Format convention
       10.2     Invalid frames
       10.3     Elements of procedures and formats of fields for data link sublayer peer-to-peer communication
                 10.3.1     Link address field format
                 10.3.2     Link address field variables
                 10.3.3     Control field formats
                 10.3.4     Control field parameters and associated state variables
                 10.3.5     Frame types
       10.4     Definition of the peer-to-peer procedures of the data link sublayer
                 10.4.1     General
                 10.4.2     Procedure for the use of the P/F-bit
                 10.4.3     Terminal Endpoint Identifier (TEI) management procedures
                 10.4.4     Automatic negotiation of data link layer parameters
                 10.4.5     Procedures for establishment and release of multiple frame operation
                 10.4.6     Procedures for information transfer in multiple frame operation
                 10.4.7     Re‑establishment of multiple frame operation
                 10.4.8     Exception condition reporting and recovery
                 10.4.9     List of system parameters
                10.4.10      Data link monitor function
                10.4.11     PSTN and control data link FSM and requirements
11     AN frame relay sublayer
       11.1     General
       11.2     Invalid frames
       11.3     Detailed description of the AN frame relay function
                 11.3.1     Frame received from LE
                 11.3.2     Frame received from ISDN user port
12     Sublayer-to-sublayer communication and mapping function
       12.1     LAPV5-EF to LAPV5-DL communication
       12.2     LAPV5-DL to LAPV5-EF communication
       12.3     AN-FR to LAPV5-EF communication
       12.4     LAPV5-EF to AN-FR communication
13     PSTN signalling protocol specification and layer 3 multiplexing
       13.1     General
                 13.1.1     Introduction
                 13.1.2     Separation of responsibilities
                 13.1.3     National specific PSTN signal information elements
       13.2     PSTN protocol entity definition
                 13.2.1     Definition of PSTN path states and explanation
                 13.2.2     Definition of PSTN protocol primitives, messages and timers
       13.3     PSTN protocol message definition and content
                 13.3.1     ESTABLISH
                 13.3.2     ESTABLISH ACK
                 13.3.3     SIGNAL
                 13.3.4     SIGNAL ACK
                 13.3.5     STATUS
                 13.3.6     STATUS ENQUIRY
                 13.3.7     DISCONNECT
                 13.3.8     DISCONNECT COMPLETE
                 13.3.9     PROTOCOL PARAMETER
       13.4     General message format and information element coding
                 13.4.1     Overview
                 13.4.2     Protocol discriminator
                 13.4.3     Layer 3 address
                 13.4.4     Message type
                 13.4.5     Coding of other information elements
                 13.4.6     Single octet information elements
                 13.4.7     Information elements with variable length format
       13.5     PSTN call control procedures
                 13.5.1     General
                 13.5.2     Handling of error conditions
                 13.5.3     Path related procedures
                 13.5.4     Non-path related procedures
                 13.5.5     Layer 3 error detection procedure
       13.6     List of system parameters
       13.7     AN and LE side state tables
14     Control requirements and protocol
       14.1     ISDN user port status indication and control protocol
                 14.1.1     General aspects
                 14.1.2     Events and function elements relevant for the control of the state machines
                 14.1.3     ISDN user port FSMs, AN(ISDN port) and LE(ISDN port)
                 14.1.4     Performance Monitoring aspects
       14.2     PSTN user port status indication and control protocol
                 14.2.1     General aspects
                 14.2.2     Events and function elements relevant for the control of the state machines
                 14.2.3     PSTN user port FSM, AN(PSTN port) and LE(PSTN port)
       14.3     Interface layer 1 maintenance requirements and protocol
                 14.3.1     Events and failure reports
                 14.3.2     Detection algorithm for events and signals
                 14.3.3     V5.1-interface layer 1 FSM
                 14.3.4     Requirements and procedures for the additional functions
       14.4     Control protocol
                 14.4.1     Control protocol message definition and content
                 14.4.2     General message format and information element coding
                 14.4.3     State definitions of the control protocol
                 14.4.4     Control protocol procedures
       14.5     V5.1-re-provisioning procedures
                 14.5.1     General aspects
                 14.5.2     Events and states
                 14.5.3     Re-provisioning FSMs
                 14.5.4     Procedures
ANNEX A – Service scenarios, architecture and functional definition of access arrangements  with an AN at the LE
        A.1     Conclusions on multiple V5-interface applications
        A.2     Conclusions on architecture aspects
        A.3     Implementation of QAN
        A.4     Requirements for the support of the PL capability through an ISDN basic access
        A.5     Assumptions and requirements for the support of semi-permanent leased lines
                  A.5.1     General
                  A.5.2     Signalling associated to semi-permanent leased lines
                  A.5.3     User ports
                  A.5.4     Requirements for non-ISDN user ports for semi-permanent leased lines
ANNEX B – Use of the protocol information elements for national PSTN protocols
        B.1     Introduction
        B.2     The placement of information elements
                  B.2.1     Information elements within the ESTABLISH message
                  B.2.2     Information elements within the ESTABLISH ACK message
                  B.2.3     Information elements within the SIGNAL message
                  B.2.4     Information elements within the DISCONNECT message
                  B.2.5     Information elements within the DISCONNECT COMPLETE message
                  B.2.6     Information elements within the PROTOCOL PARAMETER message
        B.3     The information elements
                  B.3.1     Line-information information elements
                  B.3.2     Pulse-notification information element
                  B.3.3     Autonomous‑signalling‑sequence information element
                  B.3.4     Sequence‑response information element
                  B.3.5     Cadenced‑ringing information element
                  B.3.6     Pulsed‑signal information element
                  B.3.7     Use of Pulsed‑signals
                  B.3.8     Use of Steady‑signals
                  B.3.9     Digit‑signal information element
                 B.3.10     Recognition‑time information element
                 B.3.11     Enable‑autonomous‑acknowledge information element
                 B.3.12     Default values for the Enable-autonomous-acknowledge information element
                 B.3.13     Use of the Autonomous-signalling-sequence
                 B.3.14     Disable‑autonomous‑acknowledge information element
                 B.3.15     Enable-metering information element
                 B.3.16     Metering-report information element
                 B.3.17     Attenuation information element
        B.4     Signalling sequences in the event of failures of a V5.1 interface to return a user port to the idle condition before releasing the signalling path
                  B.4.1     Protocol implications of going directly to the NULL state
                  B.4.2     Protocol implications of going to the BLOCKED state
        B.5     Leaving the BLOCKED state
        B.6     Pre‑defined PSTN port states
        B.7     The line parked condition
        B.8     Information element meaning
        B.9     Coding of pulse duration types
       B.10     Ring signals and their placement in V5 messages
       B.11     Resource unavailable
       B.12     Information flow diagrams
       B.13     Use of function element (FE) primitives in the V5-PSTN protocol
                 B.13.1     Introduction
                 B.13.2     FE primitives used in the PSTN protocol entity in the AN
                 B.13.3     FE primitives used in the PSTN protocol entity in the LE
       B.14     PSTN protocol: Explanatory notes and information flow
                 B.14.1     Explanatory notes
ANNEX C – Basic requirements of the system management functions in the AN and the LE
        C.1     Procedure for the ISDN basic access continuity test
        C.2     Port blocking
        C.3     Collision between primitives
        C.4     AN detection of hard failure and unacceptable performance
        C.5     Port unblocking
        C.6     Control and provisioning
        C.7     Verification of port state
        C.8     Permanent activation of ISDN lines
        C.9     Coordination of FSMs
       C.10     Error performance of digital section
       C.11     Provisioning verification
       C.12     Re-provisioning synchronization
                 C.12.1     Re-provisioning initiated from the LE management
                 C.12.2     Re-provisioning initiated by the AN management
                 C.12.3     Re-provisioning verification
                 C.12.4     Fallback procedure
       C.13     System startup
       C.14     PSTN DL startup
       C.15     Data link failure and reset
       C.16     PSTN restart procedure
       C.17     States in the system management procedures
       C.18     Control protocol layer 3 protection mechanism error
       C.19     Timers in the system management entity
       C.20     Failure of layer 1
       C.21     Restarting of interface using timers TC8 and TC9
       C.22     Handling of timer TV1
       C.23     Alignment of blocking/unblocking between PSTN and control protocols
ANNEX D – Protocol architecture for PSTN and ISDN user port control
        D.1     Scope
        D.2     ISDN user port status control
                  D.2.1     Functional split between LE and AN
                  D.2.2     Information transfer between LE and AN
                  D.2.3     Activation/deactivation procedure
        D.3     PSTN user port control
                  D.3.1     Information transfer between LE and AN
ANNEX E – Structures used in the V5.1interface
ANNEX F – The concept and requirements for the upgrade of a V5.1 interface into a V5.2 interface
ANNEX G – Abbreviations
ANNEX H – AN requirement for pulse dialling
ANNEX I – Layer 3 error-detection procedure
        I.1     Variables and sequence numbers
        I.2     Values of counters and timers
        I.3     Procedures
        I.4     Examples of the error detection mechanism
ANNEX J – Items identified to be pre-defined or provisioned
APPENDIX I – Bibliography