4 International Freephone Service (IFS)
4.1 Scope
4.2 References
4.3 Definitions
4.4 Symbols and abbreviations
4.5 Description
4.6 Derivation of the functional model
4.6.1
Functional model description
4.6.2 Description of functional entities
4.6.3 Relationship with basic service
4.7 IN SIB-based service feature definitions
4.7.1 Announcement for caller
4.7.2 Geographical zone call routing
4.7.3 Variable call routing
4.7.4 Additional customer service
statistics/real-time information
4.8 Information flows
4.9 SDL diagrams for functional entities
4.10 Functional entity actions
4.11 Allocation of functional entities to physical locations