Steering of roaming for 5G core roaming in an internet packet exchange network

A method for network-based Steering of Roaming (SoR) of a User Equipment (UE) subscribed to a Home Public Land Mobile Network (HPLMN) and roaming in a location where a plurality of Visited Public Land Mobile Networks (VPLMNs) have 5G network coverage, wherein the HPLMN is interconnected with the plurality of VPLMNs via an Internet Packet Exchange (IPX) network, the method comprising:

• receiving, by a Proxy server provided in the IPX network, a first N32-f message from a first VPLMN selected by the UE from the plurality of VPLMNs, wherein the first N32-f message has an embedded N12 authentication request message or an embedded N8 registration request message, wherein the first VPLMN is a non-preferred roaming partner of the HPLMN;
• extracting, by the Proxy server, a first Public Land Mobile Network Identifier (PLMN ID) of the first VPLMN from the first N32-f message;
• querying, by the Proxy, a preferred roaming partner database for the first PLMN ID to determine whether the first PLMN ID is present in the preferred roaming partner database;
• responsive to determining that the first PLMN ID is absent from the preferred roaming partner database, generating, by the Proxy server, a patch-request configured to cause a home Security Edge Protection Proxy (hSEPP) of the HPLMN to replace a Mobility Country Code (MCC) value or a Mobility Network Code (MNC) value in the embedded N12 authentication request message or the embedded N8 registration request message with a predefined value, wherein the predefined value is configured to cause the HPLMN to respond with a rejection message;
• routing, by the Proxy server, the first N32-f message and the patch-request to the hSEPP, whereby, upon validation of the patch-request, the hSEPP is configured to replace the MCC or the MNC value in the embedded N12 authentication request message or the embedded N8 registration request message with the predefined value specified in the patch-request, thereby causing the HPLMN to respond with a rejection message;
• receiving, by the Proxy server, the rejection message from the HPLMN;
• routing, by the Proxy server, the rejection message to the first VPLMN, thereby causing the first VPLMN to abort network attachment;
• receiving, by the Proxy server, a second N32-f message from a second VPLMN selected by the UE from the plurality of the VPLMNs, wherein the second VPLMN is a preferred roaming partner of the HPLMN;
• extracting, by the Proxy server, a second PLMN ID of the second VPLMN from the second N32-f message;
• querying, by the Proxy server, the preferred roaming partner database for the second PLMN ID to determine whether the second PLMN ID is present in the preferred roaming partner database;
• responsive to determining that the second PLMN ID is present in the preferred roaming partner database, routing the second N32-f message to the HPLMN, whereby the HPLMN responds with a positive response message;
• receiving, by the Proxy server, the positive response message from the HPLMN;
• and
• routing, by the Proxy server, the positive response message to the second VPLMN, thereby causing the second VPLMN to proceed with network attachment.