6 Routeing of a call from a subscriber in the same country as the HPLMN but not served by the HPLMN

03.043GPPSignalling Requirements Relating to Routing of Calls to Mobile SubscribersTS

This clause considers two configurations: where the HLR is interrogated by a gateway exchange which is part of the HPLMN (the preferred configuration), and where the HLR is interrogated by the originating LE.

6.1 Interrogation by a Gateway MSC

If the HLR is interrogated by a gateway exchange which is part of the HPLMN, the configuration is as shown in figure 3. The call is handled as described in clause 4. If the called MS has roamed outside its HPLMN the GMSC routes the call to the visited PLMN (VPLMN) as shown in figure 4.

Figure 3: Call from a subscriber in the HPLMN country of the called MS; interrogation by GMSC in the HPLMN

Figure 4: Call from a subscriber in the HPLMN country of the called MS; interrogation by GMSC in the HPLMN; called MS roamed to another PLMN

6.2 Interrogation by the Originating LE

If the HLR is interrogated by the originating LE, the configuration is as shown in figure 5. After the HLR has returned the MSRN to the originating LE, the LE routes the call to the VMSC. If the called MS has roamed outside its HPLMN the originating LE routes the call to the visited PLMN (VPLMN) as shown in figure 6. In this case, the routeing for the call does not pass through the HPLMN.

Figure 5: Call from a subscriber in the HPLMN country of the called MS; interrogation by originating LE

Figure 6: Call from a subscriber in the HPLMN country of the called MS; interrogation by originating LE; called MS roamed to another PLMN