Question: In IMS Restoration Procedures, when an I-CSCF fails to contact the assigned S-CSCF, what action does the I-CSCF take with the REGISTER request before forwarding it to a newly selected S-CSCF?
Option 1: The I-CSCF modifies the REGISTER request by removing all previous registration data.
Option 2: The I-CSCF splits the REGISTER request into two separate requests for simultaneous processing.
Option 3: The I-CSCF includes a reselection indication in the REGISTER request.
Option 4: The I-CSCF buffers the REGISTER request until the original S-CSCF becomes available.
Explanation: When an I-CSCF is unable to contact the currently assigned S-CSCF, it reselects a new S-CSCF and forwards the REGISTER request with a crucial addition - a reselection indication. This indicates to proceed as if it were an initial registration, informing the HSS to update the S-CSCF assignment for seamless service restoration.