For Key Issue #1:

1. Solution 3 and Solution 4 address how a UE which is allowed to access multiple IMS networks can decide PDU session attributes (including S-NSSAI) of a PDU session providing access to each of the IMS networks.
2. Among those solutions, adding a new parameter "IMS home network domain name" in the traffic descriptor cannot be applied to legacy UEs or Rel-17 and beyond UEs not supporting the enhancement.
3. Solution 4 requires that a different DNN is assigned for each of the IMS networks which can be accessed by a single 5GC network slice of a PLMN.
4. The only benefit of adding a new parameter "IMS home network domain name" in the traffic descriptor is that it supports the case where the IMS clients in a UE do not provide any different information (i.e., the same application identity, the same DNN, and the same P-CSCF address from the IMS clients) except for the IMS home network domain name.

• Only Solution 1 was proposed in this scenario and the solution does not qualify as a basis for the normative work. See clause 6.1.3.

• Solution 2 and Solution 4 address how P-CSCFs in different IMS networks can be selected by an SMF.
• Solution 2 requires enhancement in the 5GSM protocol.
  The only benefit provided by Solution 2 is that it supports the case where all parameters available in the SMF (e.g., SUPI, local operator policies, UE IP address, DNN) do not provide any meaningful differentiation and the IMS networks have different IMS home network domain names.
• Solution 4 does not require change in any protocol but requires that a different DNN is assigned for each of the IMS networks which can be accessed by a single 5GC network slice of a PLMN. Due to this requirement, well known IMS APN/DNN based IMS roaming may not be supported.

For Key Issue #2, there is no solution to evaluate. For Key Issue #3, there is no solution to evaluate. For Key Issue #4, there is no solution to evaluate.

For Key Issue #1 / Scenario 1, providing "IMS home network domain name" in the traffic descriptor and Solution 4 will be the basis for work in the normative phase. Other existing methods (e.g., URSP with reused traffic descriptors, UE local configuration) can be used, but they do not require normative work. For Key Issue #1 / Scenario 2, no work in the normative phase will happen. For Key Issue #1 / Scenario 3, no conclusion is made during the study phase. For Key Issue #2, no solutions within CT1 responsibility was provided, i.e. no work in the normative phase will happen. For Key Issue #3, no solutions within CT1 responsibility was provided, i.e. no work in the normative phase will happen. For Key Issue #4, no solutions within CT1 responsibility was provided, i.e. no work in the normative phase will happen.