IMS Registration signalling flow —
User not registered
R1-4b. SIP 200 OK response:
from I-CSCF1 to P-CSCF1
(21 of 22)
I-CSCF1 forwards the 200 (OK) response from S-CSCF1 to P-CSCF1 indicating that the registration was successful.
P-CSCF1 saves the value of the Service-Route header and associates it with UE1.