CONTENTS

 

 1     Scope 
 2     References 
 3     Definitions and conventions          
 4     Abbreviations and acronyms        
 5     Terminal capabilities         
        5.1     Audio capabilities  
        5.2     Video capabilities  
        5.3     Transfer rate capabilities    
        5.4     Data capabilities    
        5.5     Terminals on restricted networks: capability
        5.6     Encryption and extension-BAS capabilities 
        5.7     Null capability        
 6     Transmission     
        6.1     Transmission modes           
        6.2     Establishment of compatible modes of operation     
 7     Frame structure
 8     Basic sequences for in-channel procedures           
        8.1     Capability exchange sequence A    
        8.2     Mode switching sequence B           
        8.3     Frame reinstatement sequence C    
 9     Mode initialization, dynamic mode switching and Mode 0 forcing  
        9.1     Mode initialization procedure         
        9.2     Dynamic mode switching (see Figure 2)      
        9.3     Mode 0 forcing procedure 
        9.4     Mode mismatch recovery procedure          
        9.5     Procedure for influencing the mode transmitted from remote endpoint          
10     Recovery from fault conditions    
       10.1     Unexpected loss of synchronization or frame alignment      
       10.2     Recovery from loss of connection(s)          
11     Network consideration: call connection, disconnection and call transfer    
       11.1     Call connection     
       11.2     Terminal disconnection      
       11.3     Call transfer          
       11.4     Conferencing        
12     Procedure for activation and de-activation of data channels          
       12.1     General 
       12.2     Procedures applicable to all data types      
       12.3     Equipment capable of operating using protocol according to Recommendation ITU‑T T.120     
       12.4     Data equipment not conforming to Recommendation ITU-T T.120
       12.5     Dummy data         
13     Procedures for operation in restricted networks   
       13.1     Network aspects  
       13.2     Terminal-network configurations and properties     
       13.3     Transmission formats        
       13.4     Procedures           
14     Procedure for use of BAS-extension codes         
15     Bit occupancy and the sequencing of BAS codes 
16     Procedure for dealing with single/multiple channel interconnection 
17     Procedure for use of encryption control signal channel     
18     Transmission of network addresses         
       18.1     Address of initial connection          
       18.2     Addresses of additional connections          
19     Informative codes           
       19.1     Recommendation version identification      
       19.2     Manufacturer/type identification     
Appendix I – Initialization: Case of videophone to Recommendation ITU-T H.320, type Xb     
Appendix II – Mode-0 forcing: Case of videophone to Recommendation ITU-T H.320, type Xb     
Appendix III – Example of use of message structure     
      III.1     Initial capability exchange, including MBE-cap        
      III.2     Subsequent capability exchange, including MBE capability message
      III.3     Mode switch to non-standard mode using MBE command  
Appendix IV – Examples of symmetrical and asymmetrical transmission modes     
       IV.1     Example of symmetrical transmission mode
       IV.2     Example of asymmetrical transmission mode          
       IV.3     Example of unsymmetrical video mode      
Appendix V – Examples relating to data transmissions     
        V.1     Transfer-rate 1B, audio at 48 kbit/s, no video or video off 
        V.2     Transfer-rate 1B, audio at 16 kbit/s, no video or video off 
        V.3     Transfer-rate 1B, audio at 16 kbit/s, video on        
        V.4     Transfer-rate 2B, audio at 48 kbit/s, video on        
        V.5     Transfer-rate 2B, audio at 16 kbit/s, video on        
Appendix VI – Hierarchical capability BAS codes     
      Page
Appendix VII – Interpretation of received audio capability BAS codes     

Appendix VIII – Examples of legal and illegal capability BAS sequences     
Appendix IX     
Appendix X – An algorithm to determine whether an incoming bit stream was encoded by m-law or A-law PCM     
        X.1     Basic determination algorithm        
        X.2     Possible extensions and refinements           
Bibliography