MNP Call Flows

For call related message, there are two type of solutions defined for portability Domain:

A. Mobile Number Portability-Signaling Relay Function (MNP- SRF): it is based solution acts on SCCP addressing and also makes use of NP database.

B. IN- Related Solution: IN based solution allows the MSCs to retrieve routing information from NPDB.

A. Mobile Number Portability-Signaling Relay Function (MNP- SRF) Scenarios:

Figure- Call related case - Signalling Relay Function (SRF) solution

Call A.1: Call to a non-ported number:

Fig 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 GMSCa receives the ISUP IAM, , it requests routing information by submitting a MAP SRI to the MNP_SRF/MATF. 
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.
6. IAM requires special NOA 

Call A.2 : Call to the Ported Number – Originating Network = Subscription Network – Direct Routing:

Fig 2: Call to the Ported Number – Originating Network = 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 routing information by submitting a MAP SRI to the     MNP_SRF/MATF. 
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.

Call A.3:  Mobile Originated Call to a Ported or not known to be Ported Number – Originating Network=Subscription Network – Direct Routing

Fig3: Mobile Originated Call to a Ported or not known to be Ported Number – Direct Routing

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 routing information by submitting a MAP SRI to the MNP_SRF/MATF.
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 routing 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.

Call 4:  Call to a Ported Number – Indirect Routing

Fig4: Call to a Ported Number – Indirect Routing

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 routing information by submitting a MAP SRI to MNP_SRF/MATF.
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.

Call A.5: Call to a Ported Number  Indirect Routeing with Reference to Subscription Network 

Fig5:   Call to a Ported Number  Indirect Routeing with Reference to Subscription Network 

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.

B. IN- Related Solution:

The following network operator options are defined for the MT calls in the GMSC:

 - Terminating call Query on Digit Analysis (TQoD)

- Query on HLR Release (QoHR).

The following network operator option is defined for MO calls in VMSCA and for forwarded calls in the GMSC and VMSCB:

- Originating call Query on Digit Analysis (OQoD).

Call B.1 Call to a non-ported number, no NP query required:

Fig 6: Call to non-ported Number, no query required

1. From an Originating Exchange a call is set up to MSISDN. The call is routed to the Number range holder network being the Subscription network.
2. When GMSCB receives the ISUP IAM, it requests routeing information by submitting a MAP SRI to the HLRB including the MSISDN in the request.
3. The HLRB requests an MSRN from the MSC/VLRB where the mobile subscriber currently is registered.
4. The MSC/VLRB returns an MSRN back to the HLRB.
5. The HLRB responds to the GMSCB by sending an SRI ack with an MSRN.
6. GMSCB uses the MSRN to route the call to VMSCB.

Call B.2: TQoD  Number is not ported

Fig 7:  TQoD  Number is not ported

1. From an Originating Exchange a call is set up to MSISDN. The call is routed to the Number range holder network being the Subscription network.
2. When GMSCB receives the ISUP IAM, it will send a database query to the NPDB as a result of analysis of the received MSISDN. The MSISDN is included in the query to the NPDB.
3. The NPDB detects that the MSISDN is not ported and responds back to the GMSCB to continue the normal call setup procedure for MT calls.
4. The GMSCB requests routeing information by submitting a MAP SRI to the HLRB, including the MSISDN in the request.
5. The HLRB requests an MSRN from the MSC/VLRB where the mobile subscriber owning the MSISDN currently is registered.
6. The MSC/VLRB returns an MSRN back to the HLRB. 
7. The HLRB responds to the GMSCB by sending an SRI ack with an MSRN. 
8. GMSCB uses the MSRN to route the call to VMSCB.

Call B.3: TQoD  Number is ported

Fig 8:  TQoD  Number is ported

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 receives the ISUP IAM, it will send a database query, including the MSISDN, to the NPDB as a result of analysis of the received MSISDN.
3. The NPDB detects that the MSISDN is ported and responds back to the GMSCA with a Routeing Number pointing out the Subscription network.
4. The call is routed to the Subscription network based on the Routeing Number carried in ISUP IAM message; also the MSISDN is included in IAM.
5. The GMSCB requests routeing information by submitting a MAP SRI to the HLRB, including the MSISDN in the request. The capability to route messages to the correct HLR is required.
6. The HLRB requests an MSRN from the MSC/VLRB where the mobile subscriber currently is registered. 
7. The MSC/VLRB returns an MSRN back to the HLRB. 
8. The HLRB responds to the GMSCB by sending an SRI ack with an MSRN. 
9. GMSCB uses the MSRN to route the call to VMSCB.

Call B.4: QoHR  Number is ported

Fig 9:  QoHR  Number is ported

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 receives the ISUP IAM, it requests routeing information by submitting a MAP SRI to the HLRA including the MSISDN in the request.
3. The HLRA returns a MAP SRI ack with an Unknown Subscriber error since no record was found for the subscriber in the HLRA.
4. When GMSCA receives the error indication form the HLRA, this will trigger the sending of a database query to the NPDB, including the MSISDN in the query.
5. The NPDB detects that the MSISDN is ported and responds back to the GMSCA with a Routeing Number pointing out the Subscription network.
6. The call is routed to the Subscription network based on the Routeing Number carried in ISUP IAM message; also the MSISDN is included in IAM.
7. The GMSCB requests routeing information by submitting a MAP SRI to the HLRB, including the MSISDN in the request. The capability to route messages to the correct HLR is required.
8. The HLRB requests an MSRN from the MSC/VLRB where the mobile subscriber currently is registered. 
9. The MSC/VLRB returns an MSRN back to the HLRB.  
10. The HLRB responds to the GMSCB by sending an SRI ack with an MSRN. 
11. GMSCB uses the MSRN to route the call to VMSCB.

Call B.5: OQoD  Number is not ported

Fig 10:  OQoD  Number is not ported

1. A call is initiated by Mobile Subscriber A towards Mobile Subscriber B, using the MSISDN of the called subscriber.
2. When VMSCA receives the call setup indication, it will send a database query to the NPDB as a result of analysis of the received MSISDN, including the MSISDN in the query.
3. The NPDB detects that the MSISDN is not ported and responds back to the VMSCA to continue the normal call setup procedure for MO calls. Depending on database configuration option, the NPDB could either return a Routeing Number on not ported calls, as done for ported calls, or the call is further routed using the MSISDN number only towards the Number range holder network.
4. The call is routed to the Number range holder/Subscription network based on the MSISDN or Routeing Number carried in ISUP IAM message.
5. The GMSCB requests routeing information by submitting a MAP SRI to the HLRB, including the MSISDN in the request.
6. The HLRB requests an MSRN from the MSC/VLRB where the mobile subscriber currently is registered.
7. The MSC/VLRB returns an MSRN back to the HLRB.
8.  The HLRB responds to the GMSCB by sending an SRI ack with an MSRN.
9. GMSCB uses the MSRN to route the call to VMSCB.

Call B.6: OQoD- Number is ported

Fig 11:  OQoD- Number is ported

1. A call is initiated by Mobile Subscriber A towards Mobile Subscriber B, using the MSISDN of the called subscriber.
2. When VMSCA receives the call setup indication, it will send a database query to the NPDB as a result of analysis of the received MSISDN including the MSISDN in the query.
3. The NPDB detects that the MSISDN is ported and responds back to the VMSCA with a Routeing Number pointing out the Subscription network.
4. The call is routed to the Subscription network based on the Routeing Number carried in ISUP IAM message; also the MSISDN is included in IAM.
5. The GMSCB requests routeing information by submitting a MAP SRI to the HLRB, including the MSISDN in the request. The capability to route messages to the correct HLR is required.
6. The HLRB requests an MSRN from the MSC/VLRB where the mobile subscriber currently is registered. 
7. The MSC/VLRB returns an MSRN back to the HLRB. 
8. The HLRB responds to the GMSCB by sending an SRI ack with an MSRN. 
9. GMSCB uses the MSRN to route the call to VMSCB.