C.3 Call Scenarios

23.0663GPPRelease 17Stage 2Support of Mobile Number Portability (MNP)Technical realizationTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

The notation TT=SRI in diagrams in this clause assumes that SRI=CRMNP for ETSI and SRI = Translation Type 14 for ANSI. The use of other translation types is for further study. The message flows for the following scenarios are based on the use of an SCCP relay function in MNP-SRF(s). The message flows for the higher level relay function (e.g. TC relay) in MNP-SRF are not covered here, but the principle can be found in B.4.2. For further details of the signalling relay function, the reader is referred to [7].

C.3.1 Call to a Non-Ported Number or Number Ported into the Network

Figure C.3.1 shows the signalling involved for a call to a non-ported number or number ported into the network (see 3G TS 23.018 [3]).

Figure C.3.1: Call to a non-ported number

1. From an Originating Exchange a call is set up to MSISDN. The call is routed to the subscription network being the number range holder network, if the number is non-ported.

2. When GMSCB receives the ISUP IAM, it requests routeing information by submitting a MAP SRI to the MNP_SRF/MATF. The TT on SCCP may be set to ‘SRI’.

3. When the MNP_SRF/MATF receives the message, the MNP_SRF/MATF analyses the MSISDN in the CdPA and identifies the MSISDN as being non-ported. The MNP_SRF/MATF function then replaces the CdPA by an HLRB address. After modifying the CdPA, the message is routed to HLRB.

4. When HLRB receives the SRI, it responds to the GMSCB by sending an SRI ack with an MSRN that identifies the MSB in the VMSCB.

5. GMSCB uses the MSRN to route the call to VMSCB.

C.3.2 Call to a Ported Number – Originating Network = Subscription Network – Direct Routeing

Figure C.3.2 shows the signalling involved for a call to a ported number via direct routeing where the call is originated in the subscription network.

Figure C.3.2: Call to a ported number via direct routeing where the call is originated in the subscription network

1. MSA originates a call to MSISDN.

2. VMSCA routes the call to the network’s GMSCA.

3. When GMSCA receives the ISUP IAM, it requests routeing information by submitting a MAP SRI to the MNP_SRF/MATF. The TT on SCCP may be set to ‘SRI’.

4. When the MNP_SRF/MATF receives the message, it analyses the MSISDN in the CdPA and identifies the MSISDN as being ported into the network. The MNP_SRF/MATF function then replaces the CdPA by an HLRA address. After modifying the CdPA, the message is routed to HLRA.

5. When HLRA receives the SRI, it responds to the GMSCA by sending an SRI ack with an MSRN that identifies the MSB in the VMSCB.

6. GMSCA uses the MSRN to route the call to VMSCB.

C.3.3 Mobile Originated Call to a Ported or not known to be Ported Number – Originating Network Subscription Network– Direct Routeing

Figure C.3.3 shows the signalling involved for a national mobile originated call to a number not Subscribed in the originating network via direct routeing. The scenario describes signalling in the originating network using direct routeing in the cases when an own number is ported out, a foreign number is not known to be ported or a foreign number is ported to other foreign network.

Figure C.3.3: National mobile originated call to a ported number via direct routeing

1. MSA originates a call to MSISDN.

2. VMSCA routes the call to the network’s GMSCA.

3. When GMSCA receives the ISUP IAM, it requests routeing information by submitting a MAP SRI to the MNP_SRF/MATF. The TT on SCCP may be set to ‘SRI’.

4. When the MNP_SRF/MATF receives the message, it analyses the MSISDN in the CdPA and identifies the MSISDN as not known to be ported or being ported to another network. As the message is a SRI message, the MNP_SRF/MATF responds to the GMSCA by sending an SRI ack with a RN + MSISDN; For the case the number is not known to be ported the routeing number may be omitted.

5. GMSCA uses the (RN +) MSISDN to route the call to GMSCB in the subscription network. Depending on the interconnect agreement, the RN will be added in the IAM or not.

C.3.4 Call to a Ported Number – Indirect Routeing

Figure C.3.4 shows the signalling involved for a call to a ported number via indirect routeing.

Figure C.3.4: Call to a ported number via indirect routeing

1. From an Originating Exchange a call is set up to MSISDN. The call is routed to the number range holder network.

2. When GMSCA in the number range holder network receives the ISUP IAM, it requests routeing information by submitting a MAP SRI to MNP_SRF/MATF. The TT on SCCP may be set to ‘SRI’.

3. When the MNP_SRF/MATF receives the message, it analyses the MSISDN in the CdPA and identifies the MSISDN as being ported to another network. As the message is an SRI message, the MNP_SRF/MATF responds to the GMSCA by sending an SRI ack with a RN + MSISDN.

4. GMSCA uses the RN + MSISDN to route the call to GMSCB in the subscription network. Depending on the interconnect agreement, the RN will be added in the IAM or not.

C.3.5 Call to a Ported Number – Indirect Routeing with Reference to Subscription Network

Figure C.3.5 shows the signalling involved for a call to a ported number where indirect routeing with reference to the subscription network is used.

Figure C.3.5: National or international originated call to a ported number where indirect routeing with reference to the subscription network is used

1. From an Originating Exchange a call is set up to MSISDN. The call is routed to the number range holder network.

2. When GMSCA in the number range holder network receives the ISUP IAM, it requests routeing information by submitting a MAP SRI to the MNP_SRF/MATF. The TT on SCCP may be set to ‘SRI’.

3. When MNP_SRF/MATF receives the message, MNP_SRF/MATF operation is triggered. The MNP_SRF/MATF functionality analyses the MSISDN in the CdPA and identifies the MSISDN as being ported to another network. As the message is a SRI message, the MNP_SRF/MATF function relays the message to the subscription network by adding a routeing number to the CdPA which information may be retrieved from a database. After modifying the CdPA, the message is routed to the subscription network.

4. When MNP_SRF/MATF in the subscription network receives the SRI, it responds to the GMSCA in the number range holder network by sending a SRI ack with a RN + MSISDN.

5. GMSCA uses the (RN +) MSISDN to route the call to GMSCB in the subscription network; Depending on the interconnect agreement, the RN will be added in the IAM or not.

6. When GMSCB in the subscription network receives the ISUP IAM, it requests routeing information by submitting a MAP SRI to MNP_SRF/MATF. The TT on SCCP may be set to ‘SRI’.

7. When MNP_SRF/MATF receives the message, MNP_SRF/MATF operation is triggered. The MNP_SRF/MATF functionality analyses the MSISDN in the CdPA and identifies the MSISDN as being ported into the network. The MNP_SRF/MATF function then replaces the CdPA by an HLRB address which information may be retrieved from a database. After modifying the CdPA, the message is routed to HLRB.

8. When HLRB receives the SRI, it responds to the GMSCB by sending an SRI ack with an MSRN that identifies the MSB in the VMSCB.

9. GMSCB uses the MSRN to route the call to VMSCB.

NOTE: The MNP_SRF/MATF in this scenario has only information about all ported numbers to one subscription network, except those for which subscription information is held in the subscription networks HLR. In this scenario the routeing depends always on the number range holder and the subscription network.

C.3.6 MNP Info Query – Direct Routeing

Figure C.3.6: MNP-SRF operation for providing MNP Information where direct routeing applies

In a PLMN using a MNP-SRF based MNP solution supporting direct routeing, the INE always sends the MNP information request, containing the CdPA, to the MNP-SRF in that network.

The INE may query the MNP information for the called party number or the calling party number.

The INE requesting MNP information may be a gsmSCF for prepaid services (see 3GPP TS 23.078 [18]).

In order to provide enough information for a CAMEL SCP to charge correctly for CAMEL Pre-Paid Calls and SMS to national MSISDNs originated in the HPLMN, operators should ensure that the NPDB contains, at least, MNP information for ‘own numbers ported out’ and ‘foreign numbers ported in’.

C.3.7 MNP Info Query – Indirect Routeing

Figure C.3.7: MNP-SRF operation for Providing MNP information where indirect routeing applies

The Interrogating Network Entity (INE) submits a MNP Information request message to the MNP-SRFB, which triggers MNP-SRF operation. The MNP-SRF functionality analyses the MSISDN in the application level and queries an MNP database to get the MNP information. The INE may query the MNP information for the called party number or the calling party number.

The INE requesting MNP information may be a gsmSCF for prepaid services (see 3GPP TS 23.078 [18]).