CONTENTS

�1���� Scope
�2���� References
�3���� Definitions
�4���� Abbreviations
�5���� Overview of this Recommendation
�6���� Description of signals and messages
������� 6.1���� Escape Signal (ES)
������� 6.2���� Mode Request (MR)
������� 6.3���� Capabilities Request (CR)
������� 6.4���� Mode Select (MS)
������� 6.5���� Capabilities List (CL)
������� 6.6���� Capabilities List Request (CLR)
������� 6.7���� Acknowledge Message (ACK)
������� 6.8���� Negative Acknowledge Message (NAK)
�7���� Structure of signals and messages
������� 7.1���� Signals
������� 7.2���� Messages
�8���� Information field coding format
������� 8.1���� General
������� 8.2���� Coding format for parameters in the I and S fields
������� 8.3���� Identification field (I)
������� 8.4���� Standard information field (S)
������� 8.5���� Non-standard information field (NS)
������� 8.6���� Information field length
�9���� V.8 bis transactions
������� 9.1���� Permitted V.8 bis transactions
������� 9.2���� Transactions permitted at any time on the PSTN and on leased point-to-point circuits
������� 9.3���� Transactions permitted only upon automatic answering of a PSTN call
������� 9.4���� Use of escape signals
������� 9.5���� Use of the Negative Acknowledge Message (NAK)
������� 9.6���� State transition diagrams
������� 9.7���� Suppression of ACK(1) after an MS message
������� 9.8���� Error recovery
������� 9.9���� Procedures for initiating a modem start-up after a V.8 bis transaction
������ 9.10���� Message segmentation
10���� Operating procedures
����� �10.1���� Operating procedures when not automatically answering on the PSTN and on leased point-to-point circuits
������ 10.2���� Operating procedures upon automatic answering of a call on the PSTN
11���� DTE-DCE interface
Appendix I � Recommendation V.8 bis features
������� I.1���� Introduction
������� I.2���� Basic features of this Recommendation
������� I.3���� Selection of a desired communication mode
������� I.4���� Identification of common operating modes
������� I.5���� Automatic selection between terminals
������� I.6���� User-friendly switching from telephony to data
������� I.7���� Conferencing applications
������� I.8���� Interworking considerations
������� I.9���� Relationship between Recommendations V.8 and V.8 bis
Appendix II � Examples of V.8 bis transactions
Appendix III � Effect of echo suppressors
����� III.1���� Introduction
����� III.2���� Operation of echo suppressors
����� III.3���� Dual tone signal breakthrough of echo suppressors
����� III.4���� V.8 bis transactions 4, 5 and 6
����� III.5���� Automatic answering together with a voice recording device
����� III.6���� Optional status of provisions