Metaswitch Networks Ltd v. Sonus Networks Inc

1. Case Identification

• Case #: IPR2019-00396
• Patent #: 6,950,441
• Filed: December 5, 2018
• Petitioner(s): Metaswitch Networks Ltd. and Metaswitch Networks Corporation
• Patent Owner(s): Sonus Networks Inc.
• Challenged Claims: 1-7, 9-11, 13, 14, 16-23, 25-27, 29-30

2. Patent Overview

• Title: Method and System to Internetwork Telecommunication Networks of Different Protocols
• Brief Description: The ’441 patent relates to a "softswitch" system for interconnecting telecommunication networks that use different transport protocols, such as circuit-switched and packet-switched networks. The system discloses functional components including a "call agent," "signaling agent," "network directory server," and "network gateway" to manage and route calls.

3. Grounds for Unpatentability

Ground 1: Claims 1-4 and 16 are obvious over Lakshmi in view of Elliott

• Prior Art Relied Upon: Lakshmi (a June 1999 technical journal from Bell Labs) and Elliott (Patent 6,614,781).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that Lakshmi disclosed the core architecture of the ’441 patent’s softswitch, including a "call coordinator" that functions as the claimed "call agent" and "device servers" that function as the claimed "signaling agent." Lakshmi also taught a "directory coordinator" and "routing database" that met the limitations of the "network directory server." Petitioner argued that Elliott supplemented Lakshmi’s general disclosures by teaching specific implementation details. For example, Elliott’s "route server," with its "route logic" and "port status" components, disclosed the claimed resource manager (claim 2) and provided more detailed functionality for the network directory server (claims 1, 3, 4). Elliott also taught communication between softswitches to obtain address locations for calls terminating in external networks, mapping to the claimed "network gateway" functionality (claim 4).
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Elliott’s detailed teachings with Lakshmi’s foundational system to enhance route information storage, improve resource management, and enable robust inter-softswitch communication. Elliott provided known solutions to improve the efficiency and reliability of the type of softswitch system described by Lakshmi.
  • Expectation of Success: A POSITA would have a high expectation of success, as the combination involved integrating known routing and resource management techniques (from Elliott) into a compatible softswitch architecture (from Lakshmi) to achieve the predictable result of a more efficient and capable system.

Ground 2: Claims 5-7 and 9-11 are obvious over Lakshmi and Elliott, further in view of Volftsun and Barclay

• Prior Art Relied Upon: Lakshmi, Elliott, Volftsun (Patent 6,111,893), and Barclay (Patent 6,311,072).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground builds on the combination of Lakshmi and Elliott. Petitioner argued that Volftsun taught a protocol converter with an I/O subsystem that parses and formats incoming protocol-specific messages into Protocol Data Units (PDUs). This functionality maps directly to the claimed "codec specialized in the signaling protocol" (claims 5 and 9). Barclay was cited for its teaching of filtering erroneous or non-call-processing messages to prevent wasting system resources, which corresponds to the claimed "filter" (claims 5 and 9).
  • Motivation to Combine: A POSITA would be motivated to incorporate Volftsun’s I/O subsystem into the "device interface" of the Lakshmi/Elliott system to advantageously parse and format protocol-specific signaling, thereby improving message handling and detection. Further, a POSITA would add a filter as taught by Barclay to improve system efficiency by discarding extraneous messages, a common practice in network design.
  • Expectation of Success: Success was expected because implementing protocol-specific parsing/formatting (from Volftsun) and message filtering (from Barclay) were well-known techniques for improving the robustness and efficiency of telecommunications systems like the one described by Lakshmi and Elliott.

Ground 3: Claim 17 is obvious over Lakshmi in view of Sestak

• Prior Art Relied Upon: Lakshmi and Sestak (a 1990 IEEE conference paper).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued that Lakshmi disclosed a softswitch with "programmable back-office features," including support for billing and "call-detail event" recording, which constituted a basic "billing sub-system." Sestak provided specific teachings on generating Call Detail Records (CDRs), including generating a CDR upon call termination and including key data like "start time" and "end time." The combination of Lakshmi’s billing subsystem and Sestak’s CDR generation methods met all limitations of claim 17.
  • Motivation to Combine: Lakshmi described the need for a billing subsystem but did not elaborate on the process. A POSITA would have looked to known, resource-efficient methods for CDR generation, such as those in Sestak, to implement this feature. Combining Sestak’s teachings would reliably provide the CDRs needed for the billing functions required by the Lakshmi system.
  • Expectation of Success: There was a reasonable expectation of success because implementing CDR generation upon call termination was a standard and necessary function for any telecommunications system that required billing, making it a routine and predictable addition to Lakshmi’s system.

• Additional Grounds: Petitioner asserted that claims 1, 3, 13, and 14 are obvious over Lakshmi alone. Petitioner also asserted additional obviousness challenges against claims 18-23, 25-27, 29, and 30 based on further combinations of Lakshmi, Elliott, Capers (Patent 6,418,205), Sestak, Volftsun, and Barclay, relying on similar motivations to combine.

4. Key Claim Construction Positions

• "logic control": Petitioner proposed this term refers to the “data-configurable generic state machine processor that execute logic control programs,” consistent with the ’441 patent’s specification.
• "[logic control] program": Petitioner proposed this term refers to “actions, transitions, and data as a series of data items or independent building blocks that define what a logic engine application is to perform,” also consistent with the specification.

5. Key Technical Contentions (Beyond Claim Construction)

• Petitioner’s primary technical contention was that the Examiner erred during the original prosecution of the ’441 patent. The Examiner’s reasons for allowance were based on an impermissibly narrow claim interpretation that excluded "distributed" or "external" arrangements of the network directory server and network gateway. Petitioner argued that this interpretation contradicted the ’441 patent’s own specification, which explicitly stated these components "may be distributed." Furthermore, Petitioner contended that the primary prior art reference, Elliott, also taught that these functional components could be co-located with the softswitch or distributed.

6. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. §325(d) was inappropriate. It was argued that the prior art and arguments presented in the petition were not the same or substantially the same as those considered during prosecution, because the Examiner’s allowance was based on a flawed understanding of both the claims and the teachings of the prior art (specifically Elliott).

7. Relief Requested

• Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1-7, 9-11, 13, 14, 16-23, 25-27, 29, and 30 of Patent 6,950,441 as unpatentable.