4 Network architecture

23.0403GPPRelease 17Technical realization of the Short Message Service (SMS)TS

4.1 Basic network structure

The exchange of messages between an MS and an SME involves the entities shown in figure 4.

The architecture for providing SMS over a generic IP CAN is described in 3GPP TS 23.204 [42] (see clause 5).

The basic network structure of the SMS is depicted in figure 5.

*): SMS‑GMSC when the short message is transferred from the SC to the MS, SMS‑IWMSC when the short message is transferred from the MS to the SC. The SC may be integrated with the SMS‑GMSC/SMS‑IWMSC.

**): SGSN is used in place of the MSC for SMS transfer over GPRS.

***): The SMS Router is an optional functional entity, and is used only in the MT case.

Figure 4: Entities involved in the provision of SM MT and SM MO

The reference points of figure 5 support the short message transfer in the following way:

‑ message transfer on reference point 1 is described in clause 5;

‑ the operations performed on reference point 2 are described in 3GPP TS 29.002 [15] for MAP based interface and in 3GPP TS 29.338 [50] for Diameter based interface (S6c);

‑ the operations performed on reference point 4 are described in 3GPP TS 29.002 [15] for MAP based interface;

‑ message transfer on reference point 3 is described in clause 4.2;

‑ message transfer on reference point 5 is supported by the protocol described in 3GPP TS 24.011 [13].

‑ the operations performed on reference points 6 are described in 3GPP TS 29.118 [47].

NOTE 1: Reference point 4 is not used for SMS transfer via the SGSN

NOTE 2: The SMS Router is an optional entity that may be present in the MT case only. If it is not present, reference point 3 extends from the SMS-GMSC directly to the MSC/SGSN.

NOTE 3: Reference point 6 is used for SMS transfer when SMS over SGs is used and the MME is used to tunnel SMS messages.

Figure 5: The main network structure serving as a basis for the short message transfer

4.2 Transfer on reference point 3

Reference point 3 is used to support communications between:

– MSC <-> SMS‑GMSC / SMS‑IWMSC;

– SGSN <-> SMS-GMSC / SMS-IWMSC;

– SMS Router <-> SMS‑GMSC;

– SMS Router <-> MSC;

– SMS Router <-> SGSN.

If any of the above two end nodes are in the same PLMN, the definition of this reference point is left to the operators. For example, this reference point may use:

‑ PSPDN; or

‑ CCITT SS no 7 (according to 3GPP TS 29.002 [15]).

If any of the above two end nodes are in different PLMNs, this reference point shall use CCITT SS no 7 according to 3GPP TS 29.002 [15], unless otherwise bilaterally agreed.