23.3.3 Procedure in the Serving MSC
29.0023GPPMobile Application Part (MAP) specificationRelease 17TS
Any CAMEL-specific handling defined in this clause is omitted if the MSC does not support CAMEL control of MT SMS, or if the subscriber does not have a subscription for CAMEL control of MT SMS.
The process starts when the MSC receives a dialogue opening request with the application context shortMsgMT-RelayContext. The MAP process invokes macros not defined in this clause; the definitions of these macros can be found as follows:
Receive_Open_Ind see clause 25.1.1;
Check_Indication see clause 25.2.1.
The mobile terminated short message transfer process in the serving MSC is shown in figure 23.3/6
Procedure MT_SM_VMSC sheet 1: The decision box "TCAP Handshake required" takes the "yes" or "no" exit depending on agreements between the Serving MSC’s operator and the SMS Gateway MSC’s operator (see 3GPP TS 33.204 [34a]).
The macro MT_SM_Transfer_MSC may be invoked either in a stand-alone serving MSC or in a serving MSC which is integrated with the SMS-GMSC. It is used to transfer the first MT short message of a possible sequence of messages. The macro invokes macros not defined in this clause; the definitions of these macros can be found as follows:
Check_Confirmation see clause 25.2.2.
Page_MSC see clause 25.3.1;
Search_for_MS_MSC see clause 25.3.2;
Process_Access_Request_MSC see clause 25.4.1;
Trace_Subscriber_Activity_MSC see clause 25.9.1.
The macro MT_SM_Transfer_MSC is shown in figure 23.3/7. The macro Check_Subscr_Identity_For_MT_SMS is shown in figure 23.3/8.
3GPP TS 29.118 [152] specifies the extensions applicable to the MT SMS procedure over SGs for a UE using extended idle mode DRX (as defined in 3GPP TS 23.682 [148]).
If the MS is using a power saving mechanism such as extended idle mode DRX (see 3GPP TS 23.682 [148]), and if the MT Forward Short Message Request includes the Maximum Retransmission Time IE, an MSC using Deployment Option 2 (see clause 8.2.4a.1 of 3GPP TS 23.272 [143] and 3GPP TS 23.040 [6]) may return an MT Forward Short Message Response with the User Error set to Absent Subscriber_SM and with the Requested-Retransmission-Time IE requesting the SMS-GMSC to retransmit the Short Message at a later time prior to the Maximum Retransmission Time. In that case, the MSC shall store (if not already done) the SMS-GMSC address and, if available, the SMS-GMSC Diameter Identity received in the request and shall not set the MNRF flag.
NOTE: This mechanism does not cause additional signalling at the HSS to retransmit the Short Message.
An MSC using Deployment Option 2 (see clause 8.2.4a.1 of 3GPP TS 23.272 [143] and 3GPP TS 23.040 [6]) shall initiate the MAP Service Center Alert procedure to alert the SMS-GMSC when the UE, for which one or more MT SMS have been requested to be retransmitted at a later time, becomes available for MT SMS delivery or moves under the coverage of another MSC prior to the requested SM retransmission time. The MSC shall then delete the stored SMS-GMSC address after the Alert Service Centre procedure is completed.