23.1423GPPInterface and signalling flowRelease 17TSValue-added Services for SMS (VAS4SMS)
Short Message Auto Reply is a terminating VAS. The procedure of the short message auto reply refers to the general flow for VAS SMS described in the previous clause 7.0. The VAS AS checks that the terminating user has activated the Short Message Auto Reply service and generates an auto reply short message which contents have been defined in advance, then deliver it to the originating user.
Figure 7.8-1 Short Message auto reply procedure
NOTE: There is no requirement of the sequence for which one of auto reply message or original SM should be sent firstly in the VAS AS, i.e. auto reply message can be sent before or after original SM.
1.-4. See general flow described in the previous clause 7.0. The VAS AS checks that a terminating user has activated short message auto reply service and indicates to the SMS Node B there is terminating VAS active.
5. The VAS-AS B checks a loop prevention indication within the message. If the loop prevention indication is not set, then the VAS AS B generates an auto reply short message and set the loop prevention indication within the auto reply short message to indicate a spawned message. Otherwise an auto reply short message shall not be generated. The VAS AS B stores the original short message for next delivery.
6.-7. The VAS AS B delivers a short message which is indicated as an auto reply message to the SMS Node B.
8.-9. The auto reply short message is delivered to the originating user. See 3GPP TS 23.040 for details.
10. The VAS AS B receives a delivery report for auto reply message delivery.
11.-17. The VAS AS B continues to deliver the original short message to the terminating user. See general flow described in the previous clause 7.0.