1 Scope
2
Transport service
2.1 Transport service objectives
2.2 General structure of the transport service
3
Transport service implementation for different types of networks
3.1 Terminals connected to a PSPDN
3.2 Terminals connected to the PSTN
3.3 Terminals connected to a CSPDN
3.4 Terminals connected to an ISDN
4
Interworking between networks
5
Transport layer procedure
5.1 Transport functions
5.2 Description of connection establishment and termination
procedures
5.3 Description of data transfer procedures
5.4 Treatment of procedure errors
5.5 Formats
Annex A
A.1 Transport and network service
A.2 State transition diagrams for the basic transport layer
procedures
Annex B
B.1 State tables
B.2 Lists of events, actions and conditions
Annex C – Recommendations for implementation of Recommendation X.21
C.1 General
C.2 Receipt of call progress signals 01 or 04
C.3 Receipt of call progress signal 03
C.4 Receipt of call progress signals of the group 2 to 8
Annex D – Service definitions and state transition diagrams for the HDLC
procedure and the network layer defined for CSPDN
D.1 Service definitions
D.2 State transition diagrams HDLC
D.3 Summary of frame definitions
D.4 X.21 service, controlled by the network layer