1 Overview
1.1 Scope
1.2 References
1.3 Definitions
1.4 Abbreviations
2
Specification model
3
Look‑Ahead, application process functions
3.1 Primitive interface AP/SACF
3.2 Procedures at
initiating exchange
3.2.1 Normal procedures
3.2.2 Exceptional procedures
3.3 Procedure at an intermediate national exchange
3.4 Procedure at the outgoing screening point
3.5 Procedure at an intermediate international exchange
3.6 Procedure at the incoming screening point
3.7 Procedure at the destination local exchange
3.7.1 Normal procedures
3.7.2
Exceptional procedures
4
SACF
4.1 Interface SCCP/SACF
4.1.1 Primitives
4.1.2 Use of SCCP
5
LA-ASE
5.1 Interface LA‑ASE/SACF
5.2 Supported operation
5.3 ASE procedures
5.3.1 Dialogue beginning
5.3.2 Normal dialogue end
5.3.3 Abnormal dialogue end
5.4 Parameters
5.5 Abstract syntax, general
5.6 ASN.1 module
6
TCAP
6.1 Interface TCAP/SACF
6.1.1 Primitives
6.1.2 Use of TCAP
7
Timers
Annex A – ASN.1 module defining B-ISUP parameters applicable for LA-ASE
Annex B – Network Look Ahead Indicator parameter
B.1 Network Look Ahead Indicator parameter
B.2 Formats
B.3 Procedures
Appendix I – B‑ISUP Parameters used in the Look‑Ahead Procedure
Appendix II – Guidelines on the use of Look‑Ahead without state change
II.1 Criteria for invocation
II.1.1 High-resource connections
II.1.2 Number analysis
II.1.3 Service indications
II.1.4 Calling party indications
II.2 Criteria for precluding
use of Look-Ahead
II.3 Management of Look-Ahead criteria
II.4 Relationship between Look-Ahead and Multiparty service
Appendix III – Look‑Ahead message flow for the UNI/NNI interworking
III.1 First scenario
III.2 Second scenario
III.3 Third scenario
III.4 Fourth scenario
III.5 Fifth scenario
Appendix IV – Primitive relationships
Appendix V – Look-Ahead relationships involving Multiple Networks
Appendix VI – Coding of instruction indicators for the Network Look Ahead
Indicator