CCITT Rec. U.12 (11/1988) – TERMINAL AND TRANSIT CONTROL SIGNALLING SYSTEM FOR TELEX AND SIMILAR SERVICES ON INTERNATIONAL CIRCUITS (TYPE D SIGNALLING)
1 Signal conversion
2 General switching and signalling principles
3 Specific signalling characteristics
APPENDIX I – Possible sequences of network selection signals
APPENDIX II – Examples of network selection signals
II.1 First example (minimum sequence of network selection signals)
II.2 Second example (a sequence of network selection signals including closed user-group characters)
APPENDIX IIIa – Through-connection procedure
APPENDIX IIIb – Through-connection procedure
APPENDIX IIIc –Through-connection procedure
APPENDIX IIId – Through-connection procedure
References