Section: 4.4.2.1 Architecture to support SMS over NAS
Content: Figure 4.4.2.1-1 shows the non-roaming architecture to support SMS over NAS using the Service-based interfaces within the Control Plane. Figure 4.4.2.1-1: Non-roaming System Architecture for SMS over NAS Figure 4.4.2.1-2 shows the non-roaming architecture to support SMS over NAS using the reference point representation. Figure 4.4.2.1-2: Non-roaming System Architecture for SMS over NAS in reference point representation NOTE 1: SMS Function (SMSF) may be connected to the SMS-GMSC/IWMSC/SMS Router via one of the standardized interfaces as shown in TS 23.040[ Technical realization of the Short Message Service (SMS) ]  [5]. NOTE 2: UDM may be connected to the SMS-GMSC/IWMSC/SMS Router via one of the standardized interfaces as shown in TS 23.040[ Technical realization of the Short Message Service (SMS) ]  [5]. NOTE 3: Each UE is associated with only one SMS Function in the registered PLMN. NOTE 4: SMSF re-allocation while the UE is in RM-REGISTERED state in the serving PLMN is not supported in this Release of the specification. When serving AMF is re-allocated for a given UE, the source AMF includes SMSF identifier as part of UE context transfer to target AMF. If the target AMF, e.g. in the case of inter-PLMN mobility, detects that no SMSF has been selected in the serving PLMN, then the AMF performs SMSF selection as specified in clause 6.3.10. NOTE 5: To support MT SMS domain selection by IP-SM-GW/SMS Router, IP-SM-GW/SMS Router may connect to SGs MSC, MME and SMSF via one of the standardized interfaces as shown in TS 23.040[ Technical realization of the Short Message Service (SMS) ]  [5]. Figure 4.4.2.1-3 shows the roaming architecture to support SMS over NAS using the Service-based interfaces within the Control Plane. Figure 4.4.2.1-3: Roaming architecture for SMS over NAS Figure 4.4.2.1-4 shows the roaming architecture to support SMS over NAS using the reference point representation. Figure 4.4.2.1-4: Roaming architecture for SMS over NAS in reference point representation