S2. IMS Session Initiation signalling flow —
mobile origination and termination in home network
S2-10a. SIP 200 OK response (INVITE):
from UE2 to P-CSCF2
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When the called party answers, UE2 sends a 200 OK final response to the INVITE request to P-CSCF2, and starts the media flow(s) for this session.
P-CSCF2 approves the commitment of the QoS resources if it was not approved yet.