D.7 Usage of SCs for replying

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

The specification in this annex supports the following way of replying.

The original MT SM and the reply MO SM are delivered by the same SC, the original SC. This principle maximizes the probability that the SC can e.g. route the reply MO SM to the proper data network for reaching the originating SME; this principle is a must, if the originating SME is integrated within the original SC.

If the original SC by any means whatsoever knows that it is both willing and able to deliver one (potential) reply MO SM, it may indicate this fact by setting the TP‑Reply‑Path parameter in the original MT SM. The original SC thus commits itself to delivering one reply MO SM; let us call this reply delivery commitment.

One reason for the SC to make the reply delivery commitment may be the reply path requesting procedure specified in clause 4 on this annex.

The reply path commitment is not valid forever, but the original SC may have e.g. a time limit for maintaining this commitment.