This TS provides the protocol details for the Flexible Alerting supplementary service in the IP
Multimedia (IM) Core Network (CN) subsystem based on the requirements from TS 22.173
Flexible Alerting (FA) causes a call to a pilot identity to branch the call into several legs to alert several termination addresses (group members) simultaneously. The first leg to be answered is connected to the calling party. The other call legs are abandoned.