DCT

5:24-cv-02528

Estech Systems IP LLC v. Zoom Video Communications Inc

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Key Events
Amended Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 5:24-cv-02528, N.D. Cal., 01/16/2026
  • Venue Allegations: Venue is based on Defendant Zoom’s principal place of business being located in the Northern District of California.
  • Core Dispute: Plaintiff alleges that Defendant’s Voice over IP (VoIP) products and services infringe three patents related to VoIP system architecture, including remote phone directories, quality of service management, and cross-network voicemail access.
  • Technical Context: The technology at issue is Voice over IP, which enables voice communication over data networks and is fundamental to modern enterprise and personal communication systems.
  • Key Procedural History: This filing is a Second Amended Complaint, suggesting prior versions were challenged, potentially via a motion to dismiss. The complaint acknowledges the court previously expressed reservations regarding the sufficiency of infringement allegations for all three asserted patents. For U.S. Patent No. 8,391,298, an Inter Partes Review (IPR) proceeding (IPR2021-00574) resulted in the cancellation of claims 1-12 and 17-19. The sole asserted independent claim, Claim 13, was not cancelled and therefore survived the IPR challenge. The complaint also alleges a history of the patents-in-suit being "widely licensed" to over 20 entities, including major industry participants.

Case Timeline

Date Event
2001-02-01 Earliest Priority Date for ’298, ’684, and ’699 Patents
2006-06-27 U.S. Patent No. 7,068,684 Issues
2006-10-17 U.S. Patent No. 7,123,699 Issues
2013-03-05 U.S. Patent No. 8,391,298 Issues
2021-03-05 Inter Partes Review Filed for U.S. Patent No. 8,391,298
2025-02-12 Inter Partes Review Certificate Issues for ’298 Patent
2026-01-16 Second Amended Complaint Filed

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

U.S. Patent No. 8,391,298 - *"Phone Directory in a Voice Over IP Telephone System"*

The Invention Explained

  • Problem Addressed: The patent addresses the challenge of providing unified, easily accessible telephone directory services for an enterprise with employees and resources distributed across multiple physical locations connected by a Wide Area Network (WAN). (Compl. ¶27).
  • The Patented Solution: The invention describes a VoIP system where a user at a telephone in a first Local Area Network (LAN) can view a list of other available LANs within the enterprise system. The user can then select a remote LAN to view a directory of telephone extensions located there, with the directory information being stored on a server in the remote LAN and accessed across the WAN. (’298 Patent, Abstract; Fig. 3). This creates a transparent, system-wide directory accessible from any endpoint.
  • Technical Importance: The technology simplifies inter-office communication in a distributed VoIP environment by centralizing access to remote directories, obviating the need for manual lookups or separate directory systems. (Compl. ¶27).

Key Claims at a Glance

  • The complaint asserts independent claim 13 of the ’298 Patent. (Compl. ¶36).
  • Essential elements of Claim 13 include:
    • A telecommunications system with a first IP telephone in a first LAN and telephone extensions in a second LAN.
    • A WAN coupling the first and second LANs.
    • A third LAN coupled to the first and second LANs via the WAN.
    • A “means for displaying on the first IP telephone a list of LANs coupled to the WAN, including the second and third LANs.”
    • A “means for displaying on the first IP telephone a displayed list of the telephone destinations” from one of the selected LANs.
  • The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 7,068,684 - *"Quality of Service in a Voice Over IP Telephone System"*

The Invention Explained

  • Problem Addressed: In networks where voice and data traffic coexist, such as Ethernet, bursts of data traffic can consume available bandwidth and degrade the quality of real-time voice communications, causing issues like jitter and latency. (’684 Patent, col. 1:45-68).
  • The Patented Solution: The patent describes an IP telephone that acts as a pass-through for data from a connected workstation to the network. The telephone monitors the quality of incoming voice packets from a multimedia server. If the voice quality degrades (e.g., its jitter buffer depletes), the phone sends a "congestion message" to the server. The server then sends a "throttling signal" back, instructing the phone to restrict or "throttle" the data traffic passing through it from the workstation, thereby prioritizing bandwidth for the voice call. (’684 Patent, Abstract; col. 2:31-44).
  • Technical Importance: This approach provides a mechanism for ensuring Quality of Service (QoS) for VoIP calls by actively managing network congestion at the endpoint level, directly where data and voice traffic converge. (Compl. ¶49).

Key Claims at a Glance

  • The complaint asserts independent method claim 42 of the ’684 Patent. (Compl. ¶57).
  • Essential steps of Claim 42 include:
    • Transferring data from a workstation to a telephone, where the data is addressed for a data server.
    • Communicating audio information between the telephone and a multimedia server.
    • “sufficiently throttling the data sent from the workstation to the telephone to increase a rate of transfer of the audio information.”
    • Monitoring the amount of audio information being received by the telephone from the server.
    • The telephone sending a “congestion message” to the server when the amount of audio information “falls below the predetermined level.”
  • The complaint states it does not allege infringement of any non-method claims. (Compl. ¶57).

U.S. Patent No. 7,123,699 - *"Voice Mail in a Voice Over IP Telephone System"*

  • Technology Synopsis: The patent addresses the need for seamless voicemail access across geographically separate locations in a VoIP system. (Compl. ¶63). The invention provides a method where a user on a device in a second LAN can be notified of a new voicemail, establish a channel over a WAN to a voicemail system in a first LAN, and listen to the message, which is streamed over an audio path from the first LAN to the second. (’699 Patent, Abstract; col. 13:1-12).
  • Asserted Claims: The complaint asserts independent method claim 1. (Compl. ¶71).
  • Accused Features: The accused functionality is Zoom’s voicemail system, which allegedly stores messages on VoIP servers (the "first LAN") and allows users on Zoom phones or clients (the "second LAN") to access and listen to them via streaming protocols like RTP or SRTP. (Compl. ¶¶68-70, 72).

III. The Accused Instrumentality

Product Identification

  • The complaint names a broad suite of “Zoom Products and Services.” This includes hardware such as Zoom VoIP Phones (with and without PC ports) and certified third-party phones and network hardware, as well as software-based clients like the Zoom Mobile and Desktop App, Zoom Phone for web, and Zoom Workplace. The backend infrastructure, including Zoom Cloud VoIP Services and the Zoom Phone system, is also accused. (Compl. ¶21).

Functionality and Market Context

  • The accused instrumentalities collectively form a comprehensive VoIP communication ecosystem. Based on the complaint, this system provides functionalities for voice calling, voicemail storage and retrieval, company-wide directory services, and quality of service management. (Compl. ¶23). The complaint alleges that Zoom designs and incorporates these products and services into its customers’ network infrastructures. (Compl. ¶22).

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint.

’298 Patent Infringement Allegations

Claim Element (from Independent Claim 13) Alleged Infringing Functionality Complaint Citation Patent Citation
a first IP telephone coupled to a first IP server within a first LAN A Zoom VoIP telephony device connected to a customer's local network. ¶33 col. 16:21-23
second and third telephone extensions coupled to a second IP server within a second LAN The complaint defines the "second LAN" as Zoom's cloud infrastructure, with extensions being dial-in numbers for meetings, callback numbers, and voicemail access numbers. ¶37 col. 16:24-26
a WAN coupling the first LAN to the second LAN The internet, which connects the user's LAN to the Zoom Cloud infrastructure. ¶32 col. 16:27-29
a third LAN coupled to the first and second LANs via the WAN A separate customer site or branch location that forms its own LAN and also connects to the Zoom Cloud. ¶37 col. 16:30-31
means for displaying on the first IP telephone a list of LANs coupled to the WAN, including the second and third LANs The complaint alleges this is met by displaying telephone destinations and directories, effectively allowing a user to view destinations from the "second LAN" (Zoom Cloud) or the "third LAN" (another customer site). ¶34, ¶37 col. 16:32-35
  • Identified Points of Contention:
    • Scope Questions: A central dispute may arise over the definition of "LAN." The infringement theory requires construing Zoom's distributed cloud infrastructure as a "second LAN" and a separate customer site as a "third LAN." This conceptual mapping raises the question of whether the patent’s architecture, exemplified by distinct physical office networks, can read on a modern cloud-based system.
    • Technical Questions: What specific feature in the accused products constitutes the "means for displaying... a list of LANs"? The complaint alleges the display of directories from different conceptual LANs satisfies this element, which raises the question of whether this meets the claim's requirement to display a list of the LANs themselves.

’684 Patent Infringement Allegations

Claim Element (from Independent Claim 42) Alleged Infringing Functionality Complaint Citation Patent Citation
transferring data from the workstation to the telephone, wherein the data sent from the workstation is addressed for transmission to the data server A workstation, such as a desktop computer, sends and receives data through a Zoom VoIP Phone equipped with a PC port. ¶55 col. 20:8-12
communicating audio information between the telephone and the multimedia server VoIP calls are conducted between Zoom VoIP Phones and Zoom's VoIP servers. ¶54 col. 20:13-15
sufficiently throttling the data sent from the workstation to the telephone to increase a rate of transfer of the audio information The complaint alleges this is performed by Zoom's QoS protocols, specifically through its implementation of the "SIP Overload Control" standard. ¶56, ¶58 col. 20:16-20
monitoring an amount of the audio information being received by the telephone from the multimedia server The complaint alleges this monitoring is part of the data throttling mechanism where the phone monitors the audio information it receives from a VoIP server. ¶56 col. 20:20-23
the telephone sending a congestion message to the multimedia server when the amount of the audio information falls below the predetermined level The complaint alleges the Zoom phone sends a congestion message to the VoIP server when the amount of audio information falls below a set level, as part of the data throttling and SIP Overload Control implementation. ¶56 col. 20:24-28
  • Identified Points of Contention:
    • Scope Questions: A primary issue may be whether the functionality of the "SIP Overload Control" standard, which is typically focused on managing server processing load, is equivalent to the patent's specific "throttling" method. The patent describes an endpoint-driven process of actively disrupting data pass-through to preserve voice quality.
    • Technical Questions: Does the accused system's QoS mechanism involve the endpoint phone monitoring its own receipt of audio packets and sending a congestion message based on that local condition, as required by the claim? Or is congestion management in the accused system primarily a server-side determination based on overall system load, which may represent a different technical approach?

V. Key Claim Terms for Construction

For the ’298 Patent

  • The Term: "LAN" (Local Area Network)
  • Context and Importance: The viability of the infringement case for the ’298 Patent depends heavily on this term's scope. Plaintiff's theory requires defining Zoom's geographically dispersed cloud infrastructure as a single "LAN" and a separate customer location as another "LAN." Practitioners may focus on this term because a conventional, geographically limited definition could undermine the infringement allegation.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent’s Figure 3 depicts two distinct information processing systems (301 in Dallas, 302 in Detroit) connected via a WAN, each of which contains a LAN. (’298 Patent, Fig. 3). This could support an interpretation where a LAN is a logically coherent network serving a location, even if parts of it are virtual.
    • Evidence for a Narrower Interpretation: The patent’s foundational Figure 1 illustrates a classic LAN architecture with a PC, hub, and server in a single configuration, consistent with the common understanding of a network in a limited physical area like an office. (’298 Patent, Fig. 1). The specification refers to connecting devices "within the same building or a campus." (’684 Patent, col. 1:40-44, incorporated by reference).

For the ’684 Patent

  • The Term: "throttl[ing] the data sent from the workstation"
  • Context and Importance: This term is central because the complaint equates it with the function of the "SIP Overload Control" standard. Whether this industry standard protocol performs the specific actions described as "throttling" in the patent is a likely point of dispute.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The Summary of the Invention describes the quality of service algorithm in general terms as being used to "restrict data traffic." (’684 Patent, col. 2:28-29). This language may support a broader definition that includes various forms of traffic management.
    • Evidence for a Narrower Interpretation: The specification provides a specific technical method for throttling, describing how the IP phone may "flood the private network" between itself and the workstation with "idle patterns (jabber)" to disrupt communication. (’684 Patent, col. 2:65-68). This detailed embodiment suggests a narrower definition involving active, endpoint-initiated data-link interference, which may differ from server-based load management.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges induced infringement of the ’298 Patent based on Zoom allegedly advising, directing, and providing instructions to end-users to use the accused systems in an infringing manner. (Compl. ¶40). It alleges contributory infringement on the basis that the accused systems contain "special features" that are a material part of the invention and not suitable for substantial non-infringing use. (Compl. ¶41).
  • Willful Infringement: Willfulness is alleged for the ’298 Patent based on Zoom’s purported knowledge of the patent since at least the service of the original complaint. The complaint further alleges willful blindness based on a supposed "policy or practice of not reviewing the patents of others." (Compl. ¶42).

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

  1. A core issue will be one of definitional scope: Can the term "LAN," rooted in the patent's context of distinct physical office networks, be construed to encompass a distributed, cloud-based infrastructure as the alleged "second LAN" and a separate customer premise as the "third LAN" to satisfy the architecture required by the ’298 Patent?

  2. A key technical question will be one of functional equivalence: Does the accused system’s alleged use of the "SIP Overload Control" standard—a protocol for managing server load—perform the specific, endpoint-driven method of "throttling" described in the ’684 Patent, which details an IP phone actively disrupting data flow from a connected workstation?

  3. An evidentiary question for the ’699 Patent will be whether the facts support the complaint's clarified theory that Zoom's voicemail system operates by streaming messages using protocols like RTP/SRTP, as opposed to downloading, and whether this operation meets all steps of the claimed method for establishing a remote audio channel between two distinct LANs.