Section: 6.4.7 Security aspects of SMS over NAS
Content: Specific services of SMS over NAS are defined in TS 23.501[ System architecture for the 5G System (5GS) ]  [2], and procedures for SMS over NAS are specified in TS 23.502[ Procedures for the 5G System (5GS) ]  [8]. For registration and de-registration procedures for SMS over NAS, the details are specified in subclause 4.13.3.1 and 4.13.3.2 in TS 23.502[ Procedures for the 5G System (5GS) ]  [8]. The NAS message can be protected by NAS security mechanisms. For MO/MT SMS over NAS via 3GPP/non-3GPP when the UE has already activated NAS security with the AMF before sending/receiving SMS, the NAS Transport message shall be ciphered and integrity protected using the NAS security context by the UE/AMF as described in sub-clause 6.4 in the present document.