PTAB

IPR2017-00697

T-Mobile US Inc v. Huawei Technologies Co Ltd

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method and Device for Realizing IP Multimedia Subsystem Disaster Tolerance
  • Brief Description: The ’617 patent describes a method for disaster recovery in an IP Multimedia Subsystem (IMS) network. The method involves a Serving Call Session Control Function (S-CSCF) storing "restoration data" for a user on a central Home Subscriber Server (HSS) during registration, allowing a newly assigned S-CSCF to retrieve this data and restore service after the original S-CSCF fails, without requiring the user to re-register.

3. Grounds for Unpatentability

Ground 1: Claims 1, 5, and 7 are obvious over Phan-Anh in view of S2-060216

  • Prior Art Relied Upon: Phan-Anh (Patent 7,769,374) and S2-060216 (a 3GPP contribution titled "Reassignment for S-CSCF during the terminated call procedure," Jan. 2006).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the claimed invention is a straightforward application of well-known "checkpointing" recovery techniques to an IMS network. Phan-Anh was asserted to teach the core concept of S-CSCF disaster recovery by storing essential user data, specifically the user's Transport Address (TA) or location information, on a central storage entity (the HSS) during registration. Upon a failure where the S-CSCF restarts and loses its local data, it can then retrieve this "restoration data" from the HSS to restore service for an incoming call. S2-060216 was argued to address the analogous problem of an S-CSCF becoming completely unavailable. It explicitly disclosed a procedure where an Interrogating CSCF (I-CSCF) detects the failure of a pre-assigned S-CSCF, queries the HSS to obtain user capability requirements, selects a new S-CSCF, and forwards the session request to the new S-CSCF to continue the call.
    • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would combine Phan-Anh's data backup and restoration method with S2-060216's server re-assignment procedure. Both references addressed the same problem of S-CSCF failure in an IMS network and sought to improve service reliability. A POSITA would see the benefit of integrating Phan-Anh’s data restoration mechanism into the S2-060216 re-assignment flow to ensure the newly assigned S-CSCF had the necessary data to seamlessly take over service, creating a comprehensive disaster tolerance solution.
    • Expectation of Success: A POSITA would have a high expectation of success, as the combination involved applying a known data retrieval concept (Phan-Anh) to a known server failover process (S2-060216) within the standardized and predictable architecture of an IMS network.

Ground 2: Claims 1, 4, 5, 7, and 10 are obvious over Phan-Anh, S2-060216, and TS 23.228

  • Prior Art Relied Upon: Phan-Anh (Patent 7,769,374), S2-060216 (3GPP contribution), and TS 23.228 (a 3GPP Technical Specification for IMS, Dec. 2005).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground was presented to address a potentially narrower construction of "restoration data" that incorporates the limitations of dependent claims 4 and 10, which require the data to include "a session initiation protocol (SIP) URL of a proxy CSCF (P-CSCF)... and a contact address of the user." Petitioner argued that while Phan-Anh taught storing user location data (TA), the prevailing IMS standard at the time of the invention, TS 23.228, explicitly specified that P-CSCFs "shall be identifiable using a valid SIP URI" and that registrations always relate to a "particular contact address." Therefore, TS 23.228 was asserted to explicitly teach the specific data elements required by the dependent claims.
    • Motivation to Combine: A POSITA seeking to implement the recovery systems of Phan-Anh and S2-060216 in a modern IMS network would naturally consult the governing technical standard, TS 23.228, for implementation details. The standard provided the precise, well-established method for identifying network nodes (like the P-CSCF) and users, making its use in the combined system a matter of routine design choice to ensure interoperability and proper function.
    • Expectation of Success: Success would be expected because the combination merely involved using standard-defined data formats (from TS 23.228) within the framework of the obvious-to-combine recovery procedures taught by Phan-Anh and S2-060216.

  • Additional Grounds: Petitioner asserted an additional obviousness ground for claims 1, 4, 5, 7, and 10 based on the combination of Phan-Anh, TR 23.821, S2-060216, and TS 23.228, arguing that even if TR 23.821 (an early IMS architecture document) was not considered incorporated by reference into Phan-Anh, it would have been obvious to combine it to provide context for Phan-Anh’s solution.

4. Key Claim Construction Positions

  • Petitioner argued that the terms "restoration data" and "restoring data" should be given their plain and ordinary meaning.
  • Petitioner contended that the Patent Owner, in parallel litigation, improperly sought to narrow the construction of "restoration data" in the independent claims by importing limitations from dependent claims 4 and 10 (i.e., requiring the data to include a P-CSCF's SIP URL and a user's contact address). Petitioner argued this would violate the doctrine of claim differentiation and was unsupported by the specification.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1, 4, 5, 7, and 10 of the ’617 patent as unpatentable under 35 U.S.C. §103.