Table of Contents

Foreword
Scope
1 Reference configurations
  1.1 Customer access configuration
  1.2 Network configuration
  1.3 Interworking situation
2 Terminal adaption functions
  2.1 Adaption function for DTEs conforming to X.1
      user classes of service 3 to 6
  2.2 Adaption functions for DTEs conforming to X.1
      user class service 7
  2.3 Rate adaption functions for DTEs conforming to
      X.1 user class of service 19
  2.4 Adaption function for DTEs conforming to X.1
      user classes of service 1 and 2 or other
      asynchronous user bit rates
3 Test loops
Annex A (normative): Interchange circuits used in this
                     specification
  1 Essential and optional interchange circuits
  2 Timing arrangement
  3 Circuit 106
  4 Circuit 109
  5 Electrical/mechanical characteristics of
    interchange circuits
 Annex B (normative): X.21 Terminal adaptors - Ready
                      for data alignment procedures
  1 General
  2 Ready for data alignment for user rates of 600,
    1200, 2400, 4800, 7200, 9600, 14400, and 48000
    bit/s
  3 Ready for data alignment for user rates of 64
    Kbit/s
Annex C (normative): Message functional definitions and
                     contents, applicable at the
                     interface at the coincident S and
                     T reference point
  1 Alerting
  2 Call proceeding
  3 Connect
  4 Connect ac
  5 Disconnect
  6 Information
  7 Notify
  8 Progress
  9 Release
  10 Release complete
  11 SETUP
  12 SETUP ACKNOWLEDGE
  13 STATUS
Annex D: Asynchronous DTE TA operating sequences
  1 TA duplex operation
  2 TA half-duplex operation
  3 Automatic calling
Annex E (normative): Timer values
Annex F (normative): SDL diagrams for the protocol
                     mapping of X.21 TA's
  1 General
  2 The formal description
Annex G (informative): Flow control option for
                       Asynchronous DTE TA's
  1 Local flow control: TA to DTE
  2 End-to-end flow control: TA to TA
  3 Use of channel capacity
  4 Requirements for a TA supporting flow control
Annex H (informative): Network independent clocking
  1 General
  2 Measurement of phase differences
  3 Positive/negative compensation
  4 Encoding
Annex I (informative): BC, HLC and LLC information
                       element coding examples
                       applicable to user specific
                       applications
  1 Support of Terminal Adaptors V.110/X.30
History

Abstract

Covers the connection of X.21 and X.21 bis based terminals of user classes of service 3 to 7 and 19 to the ISDN operating in accordance with leased or circuit switched services. Does not specify a particular implementation but specifies how the functions must be implemented when they are supported by a particular Terminal Adaptor equipment.

General Product Information

Published
Document Type	Standard
Status	Current
Publisher	European Telecommunications Standards Institute
Pages
ISBN
Committee	SPS 5