23.0913GPPExplicit Call Transfer (ECT) supplementary serviceRelease 17Stage 2TS
First call: One of the subscriber A calls (answered).
Notification Indicator (NI): Indicates to each remote party in which state of the other remote party ECT was performed (active, alerting).
Redirection Number (Rdn): Includes the presentation indicator and the directory number of the other remote party.
Second call: The other subscriber A call (answered or alerting).
Subscriber A (PARTY A): The served mobile subscriber – the one who has subscribed to, and invokes the ECT Supplementary Service.
Subscriber B (PARTY B): The other party in the subscriber A first call.
Subscriber C (PARTY C): The other party in the subscriber A second call.
Subscriber D (PARTY D): The forwarded-to party when the call is forwarded by the subscriber C.
Transferred call: The resulting call after successful explicit call transfer between B and C.
In addition to those below, abbreviations used in the present document are listed in 3GPP TR 21.905 .
ECT: Explicit Call Transfer supplementary service
LI: Line Identity
NI: Notification Indicator
Rdn: Redirection number
RdnB: Redirection number of party B
RdnD: Redirection number of party D