S4. IMS Session Initiation signalling flow —
mobile origination in home network
termination in CS network
S4-1c. SIP INVITE request (UE1 to UE2):
from S-CSCF1 to BGCF1
(4 of 48)
: The S-CSCF passes this header to the BGCF for charging.
: The S-CSCF inserts this header to provide the charging function addresses to the BGCF.