IMS routing based on subscriber type

An IP Multimedia Subsystem (IMS) comprising:

• a Proxy Call Session Control Functions (P-CSCF) associated with a user equipment (UE), the P-CSCF configured to:
• receive, by the P-CSCF, a Session Initiation Protocol (SIP) registration message associated with a user equipment (UE);
• forward, by the P-CSCF, the SIP registration message to an Interrogating Call Session Control Function (I-CSCF), wherein the I-CSCF assigns the UE to a Serving Call Session Control Function (S-CSCF) based at least in part on the subscriber type associated with the UE;
• receive, by the P-CSCF, a SIP response message from the S-CSCF indicating a subscriber type associated with the UE, wherein the subscriber type is included in in a private header field and includes a predefined value of multiple predefined values that is associated with a classification of a subscriber distinct from other classes of subscriber, the classification of the subscriber indicating at least one of a class of service, a service level, or a service plan;
• and
• send, by the P-CSCF, a Policy and Charging Rules Functions (PCRF) request message to a PCRF selected from a subset of PCRFs that have been carved out for the subscriber type, wherein the PCRF request message is sent via a Diameter protocol Rx interface.

A computing device comprising:

• one or more processors;
• and
• non-transitory computer-readable media storing computer-executable instructions that, when executed by the one or more processors, cause the one or more processors to perform actions comprising:
• receiving, by a Proxy Call Session Control Functions (P-CSCF) of an IP Multimedia Subsystem (IMS), a Session Initiation Protocol (SIP) registration message associated with a user equipment (UE);
• forwarding, by the P-CSCF, the SIP registration message to an Interrogating Call Session Control Function (I-CSCF), wherein the I-CSCF assigns the UE to a Serving Call Session Control Function (S-CSCF) based at least in part on the subscriber type associated with the UE;
• receiving, by the P-CSCF, a SIP response message from the S-CSCF indicating a subscriber type associated with the UE, wherein the subscriber type is included in in a private header field and includes a predefined value of multiple predefined values that is associated with a classification of a subscriber distinct from other classes of subscriber, the classification of the subscriber indicating at least one of a class of service, a service level, or a service plan;
• and
• sending, by the P-CSCF, a Policy and Charging Rules Functions (PCRF) request message to a PCRF selected from a subset of PCRFs that have been carved out for the subscriber type, wherein the PCRF request message is sent via a Diameter protocol Rx interface.