R2. IMS Registration signalling flow —
Re-registration – User currently registered
R2-1e. SIP REGISTER request:
from I-CSCF1 to S-CSCF1
(6 of 10)
Upon receiving this request S-CSCF1 will detect that it already has a registration record for UE1 and will reset its SIP registration timer for UE1 to the Expires time in this request.