DCT

2:18-cv-00155

Sonus Networks Inc v. Metaswitch Networks Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:18-cv-00155, E.D. Tex., 04/18/2018
  • Venue Allegations: Plaintiff alleges venue is proper because Defendants have a regular and established place of business in the Eastern District of Texas and have committed acts of infringement in the district.
  • Core Dispute: Plaintiff alleges that Defendant’s telecommunications products continue to willfully infringe seven patents that were previously found to be infringed by Defendant in a prior lawsuit.
  • Technical Context: The technology domain is Voice over Internet Protocol (VoIP), focusing on methods for providing advanced telecommunications services over packet networks and ensuring interoperability between different network protocols and equipment.
  • Key Procedural History: This action follows a prior lawsuit (2:14-cv-00033, E.D. Tex.) where a jury found that Defendant infringed the same seven patents asserted in this case, and the patents were found not invalid. The current complaint alleges that despite the prior judgment and an ongoing royalty obligation, Defendant continues to infringe with "allegedly modified" or "redesigned" products, raising questions of collateral estoppel and the scope of the prior judgment.

Case Timeline

Date Event
1999-03-10 ’971 Patent Priority Date
1999-06-07 ’658 Patent Priority Date
2000-06-21 ’279 & ’589 Patents Priority Date
2000-09-28 ’561 Patent Priority Date
2000-11-28 ’427 & ’984 Patents Priority Date
2004-09-14 ’971 Patent Issue Date
2005-04-26 ’658 Patent Issue Date
2005-08-23 ’279 Patent Issue Date
2006-05-16 ’561 Patent Issue Date
2007-02-27 ’427 Patent Issue Date
2011-08-02 ’984 Patent Issue Date
2011-08-09 ’589 Patent Issue Date
2014-01-XX Original Complaint in Prior Lawsuit Filed
2018-04-18 Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 6,791,971 - "Method and Apparatus for Providing a Communications Service, for Communication and for Extending Packet Network Functionality," Issued September 14, 2004

  • The Invention Explained:
    • Problem Addressed: The patent's background describes the difficulty of providing advanced telephony services, such as toll-free calling, over packet-based networks like the Internet, as these services were traditionally available only on the Public Switched Telephone Network (PSTN) (’971 Patent, col. 1:30-47). It also notes user confusion arising from the proliferation of different toll-free dialing prefixes (e.g., 1-800, 1-888) (’971 Patent, col. 1:19-27).
    • The Patented Solution: The invention describes a system for establishing an "intelligent network" service on a packet network by replicating the architecture of the PSTN's advanced services (’971 Patent, col. 2:23-28). A network node on the IP network, acting as a Service Switching Function (SSF), receives a request for a communications service. In response, this node produces and sends a query to a Service Control Function (SCF), a database and logic node also on the IP network, to obtain the necessary instructions (e.g., a routing number) to implement the service (’971 Patent, Abstract; col. 3:56-col. 4:14).
    • Technical Importance: This technology enabled the migration of established, revenue-generating telecommunication services from the legacy circuit-switched telephone network to the emerging and more flexible IP network infrastructure.
  • Key Claims at a Glance:
    • The complaint asserts independent claims 70, 80, and 92 (Compl. ¶23).
    • The essential elements of independent claim 70, an apparatus claim, include:
      • An Internet Protocol (IP) Service Switching Function (SSF-IP).
      • A receiver for receiving, on an IP network, a message requesting a communications service.
      • A processing unit programmed to produce a query relating to the implementation of the communications service for receipt by a Service Control Function (SCF), in response to the message, to cause the service to be implemented.

U.S. Patent No. 6,885,658 - "Method and Apparatus for Interworking Between Internet Protocol (IP) Telephony Protocols," Issued April 26, 2005

  • The Invention Explained:
    • Problem Addressed: The patent identifies the challenge of interoperability in IP telephony, where various vendors and standards bodies have developed different, often incompatible, protocols for establishing media streams (e.g., MGCP, H.323, SIP) (’658 Patent, col. 2:19-54).
    • The Patented Solution: The patent discloses a "call server" architecture designed to bridge these disparate protocols. The server includes distinct "protocol agents" for each protocol it supports (e.g., an H.323 agent, an MGCP agent). These agents communicate with each other internally using a common, protocol-independent "agent interworking protocol" (AIP) that acts as a superset of the functions of the external protocols, thereby enabling translation and seamless communication between devices that could not otherwise interoperate (’658 Patent, Abstract; col. 3:10-21).
    • Technical Importance: This invention provides a centralized and scalable solution for creating unified communications networks from heterogeneous equipment, a critical requirement for carriers and enterprises seeking to avoid vendor lock-in and integrate diverse VoIP systems.
  • Key Claims at a Glance:
    • The complaint asserts independent claims 1 and 11 (Compl. ¶23).
    • The essential elements of independent claim 1, a call server claim, include:
      • A first protocol agent for communicating with a first IP telephony device according to a first IP telephony protocol.
      • A second protocol agent for communicating with a second IP telephony device according to a second IP telephony protocol.
      • An interworking agent providing functions usable by the first and second protocol agents to communicate with each other via a third, superset protocol.

Multi-Patent Capsule: U.S. Patent Nos. 6,934,279 and 7,995,589

  • Patent Identification: ’279 Patent, "Controlling Voice Communications over a Data Network," Issued August 23, 2005; ’589 Patent, "Controlling Voice Communications over a Data Network," Issued August 9, 2011.
  • Technology Synopsis: The patents address techniques for enabling and controlling communications over a data network through a user interface, allowing a control system to manage a call session on behalf of a separate voice device (Compl. ¶58; ’279 Patent, Abstract).
  • Asserted Claims: Claim 25 of the ’279 Patent and claim 15 of the ’589 Patent (Compl. ¶23).
  • Accused Features: Defendant's Multiservice Telephony Application Server (MTAS) is accused of infringement (Compl. ¶60).

Multi-Patent Capsule: U.S. Patent No. 7,047,561

  • Patent Identification: ’561 Patent, "Firewall for Real-Time Internet Applications," Issued May 16, 2006.
  • Technology Synopsis: The patent addresses a "smart firewall" that uses a hybrid approach, applying a secure but slower application proxy to signaling channels while using a faster packet filter for media (bearer) channels, with the proxy instructing the filter on which connections to allow (Compl. ¶69; ’561 Patent, Abstract).
  • Asserted Claims: Claims 6, 17, and 20 (Compl. ¶23).
  • Accused Features: Defendant's Perimeta Session Border Controller (SBC) is accused of infringement (Compl. ¶71).

Multi-Patent Capsule: U.S. Patent Nos. 7,184,427 and 7,990,984

  • Patent Identification: ’427 Patent, "System and Method for Communicating Telecommunication Information from a Broadband Network to a Telecommunication Network," Issued February 27, 2007; ’984 Patent, "System and Method for Communicating Telecommunication Information from a Broadband Network to a Telecommunication Network," Issued August 2, 2011.
  • Technology Synopsis: The patents address techniques for communicating telecommunication information for subscribers between a broadband packet network and a traditional telecommunication network, such as the PSTN (Compl. ¶80; ’427 Patent, Abstract).
  • Asserted Claims: Claim 1 of the ’427 Patent and claim 1 of the ’984 Patent (Compl. ¶23).
  • Accused Features: Defendant's media gateways, sold as Universal Media Gateways or as part of an Integrated Softswitch, are accused of infringement (Compl. ¶82).

III. The Accused Instrumentality

  • Product Identification: The complaint names Metaswitch's Integrated Softswitches (e.g., VP6010 and VP6050), Call Feature Servers (CFS), Universal Media Gateways (e.g., MG6010 and MG6050), Perimeta Session Border Controllers (SBC), and Metaswitch Telephony Application Servers (MTAS) (Compl. ¶10).
  • Functionality and Market Context:
    • The accused products collectively provide core functionality for VoIP networks, including call control, session management, media gateway services, and security. The complaint alleges these are "allegedly modified" or "redesigned" versions of products that were previously adjudicated to be infringing (Compl. ¶¶40, 51, 62, 73, 84).
    • The complaint organizes the products by the patents they are accused of infringing:
      • Softswitches and CFS provide call control and are accused of infringing the ’971 and ’658 Patents (Compl. ¶¶38, 49).
      • MTAS provides application-level telephony services and is accused of infringing the ’279 and ’589 Patents (Compl. ¶60).
      • Perimeta SBC provides network security and session management and is accused of infringing the ’561 Patent (Compl. ¶71).
      • Media Gateways bridge broadband and traditional telecom networks and are accused of infringing the ’427 and ’984 Patents (Compl. ¶82).
    • No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint does not provide specific infringement allegations mapping claim elements to features of the currently accused products. Instead, the central infringement theory is that the "allegedly modified" products continue to meet each element of the asserted claims "for at least the reasons presented in the Prior Lawsuit" (Compl. ¶¶41, 52, 63, 74, 85). This pleading strategy relies heavily on the factual and legal findings of the prior litigation.

The narrative infringement theory for the lead patents is as follows:

  • ’971 Patent Infringement Allegations: The complaint alleges that Metaswitch's softswitches (both Call Feature Servers and Integrated Softswitches) continue to infringe claims 70, 80, and 92 (Compl. ¶38). The theory is that these products function as an IP Service Switching Function that, upon receiving a service request, queries a Service Control Function to implement a communications service, thereby meeting the limitations of the asserted claims for the same reasons as the products in the prior case (Compl. ¶41).
  • ’658 Patent Infringement Allegations: The complaint alleges that Metaswitch’s softswitches also infringe claims 1 and 11 of the ’658 Patent (Compl. ¶49). The theory posits that the architecture of these products includes distinct protocol agents and an internal interworking protocol for translating between different call legs or protocols, thereby meeting the claim limitations for the same reasons established in the prior litigation (Compl. ¶52).
  • Identified Points of Contention:
    • Scope Questions: A primary question will be whether the "allegedly modified" products are legally equivalent to the previously adjudicated products. The dispute may center on whether any design changes were merely colorable or if they substantively alter the product's operation in a way that avoids one or more claim limitations as construed in the prior case.
    • Technical Questions: A key factual question is what specific technical modifications Defendant made to its products following the prior verdict. The complaint does not provide this detail, stating that Plaintiff's predecessor had not yet taken discovery on the redesigns (Compl. ¶30). The case will likely turn on evidence related to these specific changes and whether they are sufficient to design around the asserted claims.

V. Key Claim Terms for Construction

Given the reliance on a prior final judgment, claim construction may be governed by the law of the case or collateral estoppel. The complaint does not raise new construction disputes. However, the application of previously construed terms to the "allegedly modified" products will be central.

  • The Term: "Service Switching Function (SSF-IP)" (from ’971 Patent, claim 70)

    • Context and Importance: Practitioners may focus on this term because the core of the infringement allegation is that Metaswitch's softswitch performs the claimed function of receiving a service request and producing a query. The dispute will likely focus on whether the "allegedly modified" softswitch still performs this specific two-part function or has been redesigned to operate differently.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification suggests an SSF can be an "IP SSPs or call agent servers... or any data server capable of performing SSF functionality," which may support a broad definition covering various call control elements (’971 Patent, col. 4:30-33).
      • Evidence for a Narrower Interpretation: The detailed description links the SSF to a Media Gateway Controller (MGC) that is specifically programmed to "perform functions analogous to those of an SSP in an SS7 network," potentially narrowing the term to devices that closely mimic traditional PSTN architecture (’971 Patent, col. 4:62-65).

  • The Term: "interworking agent" (from ’658 Patent, claim 1)

    • Context and Importance: This term is critical because infringement depends on whether the accused softswitch uses an internal architecture with distinct software agents communicating via a common, superset protocol to bridge different telephony protocols. The key question will be whether Metaswitch's modifications eliminated such an architecture.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification states the "call server is a software entity that can execute on a single machine or on multiple machines," and that the agent can be a "software component," suggesting a flexible, functional definition rather than a rigid structural one (’658 Patent, col. 3:46-48; col. 5:41-43).
      • Evidence for a Narrower Interpretation: The patent frequently discusses specific protocols like MGCP and H.323 as examples, and Figure 4 depicts distinct "Agent Call Half" blocks. This could be argued to limit the scope to architectures that explicitly partition call logic into discrete, protocol-specific modules (’658 Patent, Fig. 4; col. 5:3-7).

VI. Other Allegations

  • Indirect Infringement: The complaint alleges inducement of infringement, asserting that Metaswitch encourages its customers to buy and use the allegedly modified products with knowledge that they infringe (Compl. ¶¶43, 54, 65, 76, 87).
  • Willful Infringement: The complaint alleges willful infringement based on Defendant's knowledge of the Asserted Patents since at least January 2014 from the "Prior Lawsuit" (Compl. ¶22). The claim for willfulness is further based on the allegation that Metaswitch deliberately chose to continue infringing with modified products despite a jury verdict, a final judgment against it, and an ongoing royalty obligation (Compl. ¶¶29, 44, 55).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A core issue will be one of legal preclusion: To what extent are the claim construction, validity, and infringement findings from the prior lawsuit binding on the parties in this new action concerning "allegedly modified" products? The case may serve as a test for the boundaries of collateral estoppel in follow-on patent litigation.
  • A key evidentiary question will be one of technical distinction: What are the specific technical differences between the products previously found to infringe and the currently accused products, and are these differences sufficient to take the products outside the scope of the asserted claims as construed in the prior case?
  • A central question for damages will be willfulness and intent: If infringement is found, did the Defendant's decision to continue selling modified products constitute objective recklessness in light of the prior verdict and final judgment, potentially warranting enhanced damages?