5.2 Normal operation

22.0793GPPService definitionStage 1Support of Optimal Routeing (SOR)TS

In the first phase of SOR, the routes of calls will be optimised for the cases of OR being performed within a country or towards the country where the call would have been routed normally.

Under all other circumstances, the basic call routing is applied:

– If the IPLMN detects that basic OR cannot be applied, the IPLMN routes the call according to the dialled number.

– If the IPLMN detects that OR for Late Call Forwarding cannot be applied, the Call Forwarding will be performed in the VPLMN of the forwarding subscriber.

If the serving network of the ultimate destination supports SOR, the serving network of the caller shall be able to indicate to the network visited by the ultimate destination that the call has been optimally routed and to indicate the originating PLMN of the optimally routed leg.

The complete set of scenarios included in phase 1 of SOR is described below.

The notation used for the scenario diagrams is defined in figure 1.

Figure 1: Notation used in scenario diagrams

If one of those scenarios occurs, SOR shall be invoked.

The assumptions taken are the following :

– A subscriber A sets up a call to a mobile subscriber B, who may have forwarded her calls to a subscriber C.

– The C subscriber may be either a fixed subscriber or a mobile subscriber.

If C is a mobile subscriber, the location of C taken into account in the following paragraphs is the location of HPLMN-C.