Section: 4.23.7.2.2 Preparation phase
Content: Compared to the procedure in clause 4.9.1.3.2, the SMF interacting with the S-UPF, T-UPF, S-AMF and T-AMF is the I-SMF. The difference is following: - Step 3: The N14 context exchanged between S-AMF and T-AMF contains the SM Context ID at I-SMF, or SM Context ID at SMF if I-SMF is not applicable before. - Step 4: The T-AMF determines whether Target I-SMF needs to be selected based on UE location and service area of the SMF. In this case no I-SMF change or removal is needed. - Step 5: The I-SMF checks whether I-UPF needs to be reallocated, i.e. select a T-UPF.