S2. IMS Session Initiation signalling flow —
mobile origination and termination in home network
S2-1e. SIP INVITE request (UE1 to UE2):
from S-CSCF2 to P-CSCF2
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S-CSCF#2 remembers (from the registration procedure) UE2 Contact address and the next hop CSCF for UE2.
: Built from the Path header stored at registration.
: S-CSCF2 adds itself.
: Includes the dialled URL with its parameters.