US 2018/0007612 A1Published application

Restoration of serving call session control and application server function

AssigneeT-Mobile USA, Inc.

InventorsZeeshan Jahangir, Shujaur Mufti

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Abstract

A communication session for a UE can be restored in the event of serving call session control function (S-CSCF) node unavailability and/or application server (AS) unavailability by storing, prior to IMS unavailability, attribute-value pairs (AVPs) at a home subscriber server (HSS). These AVPs can be used independently by individual IMS nodes to restore a communication session for a UE due to an unavailable IMS node. When a first S-CSCF node becomes unavailable, a proxy CSCF (P-CSCF) node can send a SIP request originating from the UE to a second S-CSCF node. The second S-CSCF node can then send a request to the HSS for an identifier of an AS associated with the UE. Upon receipt of the AS identifier (e.g., an active AS name AVP) from the HSS, the second S-CSCF node can send the SIP request to the AS in order to restore the communication session for the UE.

Claims20

Dependent claims

A method comprising:

sending, from an application server (AS) as part of a registration procedure for a user equipment (UE), a value for an active AS name attribute-value pair (AVP) to a home subscriber server (HSS) for storage at the HSS, the value for the active AS name AVP identifying the AS as a serving AS for the UE;
receiving, at a proxy call session control function (P-CSCF) node, a Session Initiation Protocol (SIP) request originating from the UE as part of a communication session;
determining, by the P-CSCF node in response to making an attempt to contact a first serving call session control function (S-CSCF) node that was assigned to the UE as part of the registration procedure, that the first S-CSCF node is unavailable;
selecting, by the P-CSCF node, a second S-CSCF node;
sending, by the P-CSCF node, the SIP request to the second S-CSCF node;
sending, by the second S-CSCF node, and to the HSS, a request for the value for the active AS name AVP associated with the UE;
receiving, at the second S-CSCF node, and from the HSS, a response including the value for the active AS name AVP;
and
sending, by the second S-CSCF node, the SIP request to the AS identified by the value for the active AS name AVP.

6 more elements

A method comprising:

receiving, via a communications interface of a proxy call session control function (P-CSCF) node, a Session Initiation Protocol (SIP) request originating from a UE as part of a communication session;
determining, by the P-CSCF node in response to making an attempt to contact a first serving call session control function (S-CSCF) node that was assigned to the UE as part of a registration procedure, that the first S-CSCF node is unavailable;
selecting, by the P-CSCF node, a second S-CSCF node;
sending, via the communications interface of the P-CSCF node, the SIP request to the second S-CSCF node;
sending, via a communications interface of the second S-CSCF node, and to a home subscriber server (HSS), a request for an identifier of an application server (AS) associated with the UE;
receiving, via the communications interface of the second S-CSCF node, and from the HSS, a response including the identifier of the AS;
and
sending, via the communications interface of the second S-CSCF node, the SIP request to the AS.

5 more elements

Dependencies are inferred from the claim text.