B.1 Handling of Non-call Related Signalling

03.663GPPStage 2Support of GSM Mobile Number Portability (MNP)TS

B.1.1 Routeing Conventions

Figure B.1.1 illustrates the routeing of non-call related signalling messages between networks in a number portability environment.

Figure B.1.1: Routeing of non-call related signalling messages in a number portability environment

If a non-call related signalling message is originated outside the portability domain, this message (1) is received by the number range holder network. The number range holder network routes the message (5) onward to the subscription network.

If a non-call related signalling message is originated in a network inside the portability domain and this network supports direct routeing, this message (3) is routed to the subscription network.

If a non-call related signalling message is originated in a network inside the portability domain and this network does not support direct routeing, the message (2, 4) is routed to the number range holder network. The number range holder network routes the message (5) onward to the subscription network. This is referred to as indirect routeing.

B.1.2 Network Architecture

In a PLMN which supports MNP, non-call related signalling messages as mentioned in clause B.1.1 are relayed by an MNP-Signalling Relay Function (MNP-SRF). The MNP-SRF provides re-routeing capability for signalling messages addressed using the MSISDN. The MNP-SRF obtains routeing information from the NP database to identify the subscription network associated with a particular national MSISDN. The interface between the MNP-SRF and the NP database is considered implementation dependent and is not detailed further. For further details see clause 4.3.

From the perspective of the PLMN in which the MNP-SRF resides, the MSISDN in the CdPA represents either:

  1. An own number ported out;
  2. An own number not ported out;
  3. A foreign number ported in;
  4. A foreign number ported to a foreign network;
  5. A foreign number not known to be ported.

When a PLMN supports direct routeing (clause B.1.1), all non-call related signalling messages where the MSISDN in the CdPA belongs to a number range owned by a PLMN in the portability domain and all non-call related signalling messages which are relayed towards the network, are routed to the PLMN’s MNP-SRF for treatment.

In case 2 and 3 the MNP-SRF relays the message to the HLR.

In case 1, 4 and 5 the MNP-SRF relays the message to subscription network.

When a PLMN does not support direct routeing, only non-call related signalling messages where the MSISDN in the CdPA belongs to a number range owned by the PLMN itself and all non-call related signalling messages which are relayed towards the network are routed to the PLMN’s MNP-SRF for treatment. All other messages are routed to the number range holder network.

For this routeing convention, only cases 1, 2 and 3 are applicable:

In case 2 and 3 the MNP-SRF relays the message to the HLR.

In case 1 the MNP-SRF relays the message to the subscription network.