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): Casimir M. Kaczmarczyk, et al.
• 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 describes a "softswitch" for interconnecting different telecommunication networks, such as a packet-switched network and a circuit-switched Public Switched Telephone Network (PSTN). The system uses modular software components, including a "signaling agent" to handle protocol translation and a "call agent" to manage call logic and control.

3. Grounds for Unpatentability

Ground 1: Claims 1, 3, 13, and 14 are obvious over Lakshmi

• Prior Art Relied Upon: Lakshmi (Ramnath A. Lakshmi-Ratan, The Lucent Technologies Softswitch—Realizing the Promise of Convergence, Bell Labs Technical Journal, June 1999).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Lakshmi taught all elements of the independent claims. Lakshmi described a "softswitch" architecture with "device servers" that function as the claimed "signaling agent," receiving incoming signaling (e.g., SS7, SIP), translating it into an internal format ("call model event"), and routing it to a "call coordinator." This "call coordinator" performed the functions of the claimed "call agent," managing call processing and state. Lakshmi also disclosed a "directory coordinator" accessing a "routing database," which corresponds to the claimed "network directory server" used for routing and address resolution.
  • Motivation to Combine (for §103 grounds): Not applicable as this ground relies on a single reference. Petitioner asserted Lakshmi alone renders the claims obvious.

Ground 2: Claims 1-4 and 16 are obvious over Lakshmi in view of Elliott

• Prior Art Relied Upon: Lakshmi (Bell Labs Technical Journal, June 1999) and Elliott (Patent 6,614,781).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon the teachings of Lakshmi by adding specific implementation details from Elliott. While Lakshmi provided the general softswitch framework, Elliott was alleged to teach more advanced functionalities. Specifically, Elliott described a "route server" with distinct "route logic" and "port status" components. The "route logic" provided detailed routing information (mapping to the network directory server), while the "port status" component provided resource availability information (mapping to the resource manager of claim 2). Elliott also detailed inter-softswitch communication for calls terminating in an external network, mapping to the network gateway functionality.
  • Motivation to Combine (for §103 grounds): A POSITA would combine Elliott's specific solutions with Lakshmi's general architecture to enhance system performance and reliability. Integrating Elliott's "route logic" would improve routing efficiency, and adding its "port status" component would provide a known method for resource management, a conventional feature of call processing systems.
  • Expectation of Success (for §103 grounds): A POSITA would have a reasonable expectation of success because it involved applying known techniques (Elliott's detailed routing and resource management) to a known system (Lakshmi's softswitch) to achieve predictable improvements.

Ground 3: Claims 5-7, 9-11 are obvious over Lakshmi, Elliott, Volftsun, and Barclay

• Prior Art Relied Upon: Lakshmi (Bell Labs Technical Journal, June 1999), Elliott (Patent 6,614,781), Volftsun (Patent 6,111,893), and Barclay (Patent 6,311,072).

• Core Argument for this Ground:

  • Prior Art Mapping: This combination used Lakshmi and Elliott as the base system and added Volftsun and Barclay to teach the specific elements of claims 5, 9, and their dependents. Volftsun described a protocol conversion engine with an I/O subsystem that parsed and formatted incoming protocol-specific messages, teaching the "codec" functionality of claims 5 and 9. Barclay was cited for its teaching of filtering out erroneous or non-call-processing-related messages to improve efficiency, mapping to the "filter" element.
  • Motivation to Combine (for §103 grounds): A POSITA would combine Volftsun's I/O subsystem with Lakshmi's "device interface" to provide a well-understood mechanism for parsing and formatting signaling messages. It would be obvious to use a filter, as taught by Barclay and general knowledge, between the codec and logic control to ensure that only valid, relevant messages are processed, thereby preventing errors and conserving system resources.
  • Expectation of Success (for §103 grounds): Success was expected as this involved integrating well-known, modular functions (parsing, formatting, filtering) into a softswitch architecture to improve its robustness and efficiency, which are predictable outcomes.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including combining Lakshmi with Sestak (for billing subsystem and call detail record generation in claim 17) and with Capers (for verifying incoming circuit validity in claim 18). A final ground combined all references (Lakshmi, Elliott, Capers, Sestak, Volftsun, and Barclay) to address the most detailed dependent claims.

4. Key Claim Construction Positions

• "logic control" (claims 5, 9, 16, etc.): 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" (claims 5, 9, 16, etc.): Petitioner proposed this 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 based on the specification. These constructions were central to arguing that the prior art's software-based components met the claimed limitations.

5. Key Technical Contentions (Beyond Claim Construction)

• Petitioner's central technical contention was that the Examiner's reasons for allowance during prosecution were based on a legally erroneous claim interpretation. The Examiner concluded that prior art teaching "external" or "distributed" components (e.g., a network directory server) did not meet the claim limitations. Petitioner argued this was a fatal error because the '441 patent's own specification explicitly states that components like the network directory server "may reside on the same platform as [the] call agent... or may be distributed." Thus, Petitioner contended that the prior art, particularly Elliott, was improperly dismissed.

6. Arguments Regarding Discretionary Denial

• Petitioner argued that denial under §325(d) would be inappropriate because the prior art and arguments presented in the petition were not the same or substantially the same as those before the Examiner. Specifically, Petitioner noted that a rejection during prosecution based on Elliott and Capers was withdrawn due to a perceived deficiency in Elliott. Petitioner argued its current combination, including Lakshmi, remedies that perceived deficiency, presenting a new question of patentability that was not previously considered by the Office.

7. Relief Requested

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