ITU-T Rec. Q.84 (19929 – STAGE 2 DESCRIPTION FOR MULTIPARTY SUPPLEMENTARY SERVICES
FOREWORD
2 Three-Party Service (3PTY)
    2.1 Scope
    2.2 Normative references
    2.3 Definitions
    2.4 Symbols and abbreviations
    2.5 Description
    2.6 Derivation of the functional model
        2.6.1 Functional model description
        2.6.2 Description of the functional entities
        2.6.3 Relationship with a basic service
    2.7 Information flows
        2.7.1 Information flow diagrams
        2.7.2 Definition of individual information flows
    2.8 SDL diagrams for function entities
    2.9 Functional entity actions (FEAs)
        2.9.1 FEAs of FE1
        2.9.2 FEAs of FE2
        2.9.3 FEAs of FE3 (i.e. FE3a and FE3b)
    2.10 Allocation of functional entities to physical locations
    2.11 Interaction with other supplementary services
        2.11.1 Advice of charge services
        2.11.2 Call Waiting
        2.11.3 Call Hold
        2.11.4 Call Transfer
        2.11.5 Number identification services
        2.11.6 Closed User Group
        2.11.7 Completion of Calls to Busy Subscriber
        2.11.8 Conference services
        2.11.9 Direct-Dialling-in
        2.11.10 Diversion services
        2.11.11 Freephone
        2.11.12 Malicious Call Identification
        2.11.13 Multiple Subscriber Number
        2.11.14 Sub-addressing
        2.11.15 Terminal Portability
        2.11.16 Three-Party Service
        2.11.17 User-to-User Signalling