23.0403GPPRelease 17Technical realization of the Short Message Service (SMS)TS
The discussion in this clause applies to cases when the originating SME is a mobile station only. The reply procedures discussed in the clauses to follow this one are independent of the type of the originating SME.
The reply path is requested by the originating SME (an MS) by setting the TP‑Reply‑Path parameter in the SMS SUBMIT PDU of the original SM. If the original SC supports reply path requesting for the originating SME (an MS), it shall take notice of the TP‑Reply‑Path parameter in the SMS‑SUBMIT PDU and set the TP‑Reply‑Path parameter in the SMS‑DELIVER PDU of the original MT SM towards the replying MS. Hence, reply path exists for the replying MS towards the originating SME (an MS).