An EPS network using SMS in MME delivers short message services over EPS NAS signalling. For the architecture and the definition of reference points for SMS in MME see TS 23.272, Annex C. Between the architecture and the reference points for SMS in MME and the architecture and the reference points shown in clause 4.1, Figure 5, of the present specification the following mapping can be established:

For the purpose of supporting SMS in MME, the MME shall implement the requirements specified in the present specification for the MSC and the VLR with the following modifications:

1. "GSM/UMTS system" is to be replaced with "EPS".
2. Throughout the text and in the figures, message names, parameter names and cause values:
   • "MSC" is to be replaced with "MME";
   • "VLR" is to be replaced with "MME internal subscriber register";
   • "HLR" is to be replaced with "HSS/HLR";
   • "MS" is to be replaced with "UE";
   • "non GPRS" is to be replaced with "EPS";
   • "IMSI detached" is to be replaced with "EPS detached".
3. The protocol used on reference point 2 (reference point S6c) is based on Diameter (see TS 29.338).
4. The protocol used on reference point 3 is based on Diameter (see TS 29.338).
5. Reference point 4 is MME internal, and operations performed on this reference point are not standardized. In the message flows of clause 10, the MME replaces the combination of MSC and VLR, and messages exchanged between MSC and VLR are replaced with MME internal communication.
6. The protocol used between HSS and MME (reference point S6a) is based on Diameter (see TS 29.272). In the alert procedure in clause 10.3:
   MAP ReadyForSM is to be replaced with Diameter NotifyRequest (ReadyforSM).

The registration (and removal of registration) procedures for SMS in MME are described in TS 23.272.