Methods and apparatuses for facilitating p-cscf restoration when a p-cscf failure has occured

A method, performed by a server for subscription data, the method comprising:

• receiving identification information from a core network node for mobility management to indicate the core network node supports a restoration procedure for a Proxy Call Session Control Function (P-CSCF);
• receiving an indication of a P-CSCF restoration in a case where the P-CSCF has failed;
• and
• transmitting the indication of the P-CSCF restoration using the identification information, to the core network node to cause the core network node to release an Internet Protocol (IP) multimedia subsystem (IMS) connection of a corresponding user equipment (UE).

A method, performed by a core network node for mobility management for facilitating a restoration procedure for a Proxy Call Session Control Function (P-CSCF), the method comprising:

• providing, to a server for subscription data, identification information to indicate that the core network node supports the restoration procedure for the P-CSCF;
• receiving an indication of a P-CSCF restoration from the server for subscription data in a case where the P-CSCF has failed after providing the identification information;
• and
• releasing an Internet Protocol (IP) multimedia subsystem (IMS) connection of a corresponding user equipment (UE) in response to receiving the indication from the server for subscription data.

A method, performed in a communication system, for facilitating a restoration procedure for a Proxy Call Session Control Function (P-CSCF) in an Internet Protocol (IP) multimedia subsystem (IMS), the method comprising:

• a core network node for mobility management providing identification information for indicating the core network node supports the restoration procedure for the P-CSCF to a server for subscription data;
• the server for subscription data receiving the identification information from the core network node;
• the core network node receiving an indication of a P-CSCF restoration from the server for subscription data in a case where the P-CSCF has failed after the core network node providing the identification information;
• and
• the core network node releasing an Internet Protocol (IP) multimedia subsystem (IMS) connection of a corresponding user equipment (UE) in response to receiving the indication from the server for subscription data.

A server for subscription data, comprising:

• a memory storing instructions;
• and
• at least one processor configured to process the instructions to:
• receive identification information from a core network node for mobility management to indicate the core network node supports a restoration procedure for a Proxy Call Session Control Function (P-CSCF),
• receive an indication of a P-CSCF restoration in a case where the P-CSCF has failed, and
• transmit the indication of a P-CSCF restoration using the identification information, to the core network node to cause the core network node to release an Internet Protocol (IP) multimedia subsystem (IMS) connection of a corresponding user equipment (UE), wherein the P-CSCF has failed.

An apparatus for facilitating a, restoration procedure for a Proxy Call Session Control Function (P-CSCF), comprising:

• a core network node for mobility management, including:
• a memory storing instructions;
• and
• at least one processor configured to process the instructions to:
• providing, to a server for subscription data, identification information to indicate that the core network node supports the restoration procedure for the P-CSCF,
• receive an indication of a P-CSCF restoration from the server for subscription data in a case where the P-CSCF has failed after providing the identification information, and
• release an Internet Protocol (IP) multimedia subsystem (IMS) connection of a corresponding user equipment (UE) in response to receiving the indication from the server for subscription data.

A communication system, for facilitating a restoration procedure for a Proxy Call Session Control Function (P-CSCF) in an Internet Protocol (IP) multimedia subsystem (IMS), the communication system comprising:

• a core network node for mobility management;
• and
• a server for subscription data, wherein
• the core network node is configured to provide identification information for indicating the core network node supports the restoration procedure for the P-CSCF to the server for subscription data,
• the server for subscription data is configured to:
• receive the identification information from the core network node, and
• the core network node is configured to:
• receive an indication of a P-CSCF restoration from the server for subscription data in a case where the P-CSCF has failed after providing the identification information, and
• release an Internet Protocol (IP) multimedia subsystem (IMS) connection of a corresponding user equipment (UE) in response to receiving the indication from the server for subscription data.