DCT

5:24-cv-02528

Estech Systems IP LLC v. Zoom Video Communications Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 5:24-cv-02528, N.D. Cal., 04/07/2025
  • Venue Allegations: Plaintiff alleges venue is proper in the Northern District of California because Defendant's principal place of business is located within the district.
  • Core Dispute: Plaintiff alleges that Defendant’s Voice over IP (VoIP) products and services infringe three patents related to VoIP phone directories, quality of service management, and remote voicemail access.
  • Technical Context: The technology at issue resides in the field of VoIP systems, which enable integrated voice, data, and messaging services over packet-switched networks like the Internet.
  • Key Procedural History: Plaintiff states that the asserted patents have been licensed over 20 times to entities including Cisco, Microsoft, and Avaya. An inter partes review (IPR) was concluded for U.S. Patent No. 8,391,298 on February 12, 2025, resulting in the cancellation of claims 1-12 and 17-19. The single claim asserted from this patent in the complaint, claim 13, was not cancelled and therefore survived the IPR proceeding.

Case Timeline

Date Event
2001-02-01 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 IPR Filed for U.S. Patent No. 8,391,298 (IPR2021-00574)
2025-02-12 IPR Certificate Issued for U.S. Patent No. 8,391,298
2025-04-07 Complaint Filing Date

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

U.S. Patent No. 8,391,298 - Phone Directory in a Voice Over IP Telephone System (Issued Mar. 5, 2013)

The Invention Explained

  • Problem Addressed: As businesses adopt VoIP systems across multiple physical locations, there is a need to provide users with directory features that are not confined to their local office, making the multi-site network feel like a single, unified system. (Compl. ¶27; ’298 Patent, col. 1:43-61).
  • The Patented Solution: The invention describes a telecommunications system where a user at a VoIP telephone on a first Local Area Network (LAN) can access a server on a second, remote LAN via a Wide Area Network (WAN). The user can view lists of available remote sites (LANs), select one, and then browse a directory of extensions at that selected site to initiate a call, creating a geographically transparent user experience. (’298 Patent, Abstract; col. 10:51-67).
  • Technical Importance: This technology provided a method for integrating disparate phone systems over a data network, allowing users at one location to seamlessly find and contact users at another as if they were on the same local system. (Compl. ¶28).

Key Claims at a Glance

  • The complaint asserts independent claim 13. (Compl. ¶36).
  • Essential elements of claim 13 include:
    • A system with a first IP telephone on a first LAN and telephone extensions on a second LAN, connected by a WAN.
    • Means for displaying on the first IP telephone a list of telephone destinations stored on a server in the second LAN.
    • Means for automatically dialing a selected destination from the list.
    • Means for displaying a list of LANs coupled to the WAN.
    • Means for displaying the list of telephone destinations in response to a user selecting a specific LAN from the list of LANs.

U.S. Patent No. 7,068,684 - Quality of Service in a Voice Over IP Telephone System (Issued Jun. 27, 2006)

The Invention Explained

  • Problem Addressed: In a shared network environment like Ethernet, real-time VoIP traffic must compete for bandwidth with "bursty" data transfers (e.g., large file downloads). This can introduce latency and jitter, which severely degrades call quality. (’684 Patent, col. 1:47-68).
  • The Patented Solution: The invention proposes a VoIP phone that acts as a traffic-managing gateway for a workstation connected through it. The phone monitors its own voice-data buffer; if congestion is detected (i.e., the buffer level drops), it sends a "congestion message" to a central server. The server responds with a "throttling signal" that instructs the phone to restrict data flow from the attached workstation, thus preserving bandwidth for the real-time voice call. (’684 Patent, Abstract; col. 2:30-45).
  • Technical Importance: The invention provides a dynamic Quality of Service (QoS) mechanism that prioritizes voice traffic by actively managing data congestion at the network edge, directly from the user's telephone. (’684 Patent, col. 2:16-19).

Key Claims at a Glance

  • The complaint asserts method claims, including dependent claim 42. (Compl. ¶56). The independent claim from which it depends, claim 29, is analyzed here.
  • Essential steps of independent method claim 29 include:
    • Transferring data from a workstation through a telephone, where the data is addressed to a data server.
    • Communicating audio information between the telephone and a multimedia server.
    • Sufficiently throttling the data sent from the workstation to increase the rate of audio information transfer.
    • This throttling step includes monitoring the amount of audio information being received by the telephone from the server.
  • The complaint states that no non-method claims are being asserted. (Compl. ¶56).

U.S. Patent No. 7,123,699 - Voice Mail in a Voice Over IP Telephone System (Issued Oct. 17, 2006)

The Invention Explained

  • Technology Synopsis: This patent addresses challenges with accessing voicemail in a multi-site VoIP environment, where a user's voicemail may be stored on a server at a different physical location from the user. (’699 Patent, col. 2:51-61). The patented method provides a sensory indication (e.g., a message waiting light) on a user's phone on a second LAN when a message is stored in a voice mailbox on a first LAN, and enables the user to connect across a WAN to retrieve and listen to that message. (Compl. ¶61, ¶67-68).

Key Claims at a Glance

  • Asserted Claims: The complaint asserts method claims, including independent claim 1. (Compl. ¶69).
  • Accused Features: The allegations target Zoom's VoIP servers that store voicemail messages and Zoom's VoIP phones, which allegedly provide sensory indications for new voicemails and enable users to establish a connection to retrieve those messages from remote servers. (Compl. ¶¶66-68).

III. The Accused Instrumentality

Product Identification

The complaint broadly identifies the "Accused Instrumentalities" as "Zoom Products and Services." (Compl. ¶21). This includes a wide range of hardware and software, such as Zoom VoIP Phones (including specific models from AudioCodes and Grandstream), the Zoom Mobile and Desktop App, Zoom Phone for web, telephony network hardware like session border controllers, and backend services like Zoom Cloud VoIP Services and Zoom Phone. (Compl. ¶21).

Functionality and Market Context

The accused products are alleged to form an integrated communications ecosystem that provides VoIP-based voice calling, voicemail storage and access, and directory services. (Compl. ¶21, ¶23). The complaint alleges these products are offered to customers in California and nationwide for incorporation into their existing network infrastructure. (Compl. ¶6, ¶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; The Accused Instrumentalities include VoIP telephony devices connected to LANs and IP servers. ¶33, ¶35 col. 4:1-12
...means for displaying on the first IP telephone a list of telephone destinations that are stored in an IP server... The accused VoIP telephony devices include a means to display a list of telephone destinations stored in an IP server. ¶34(i) col. 10:51-57
...means for automatically dialing one of the telecommunications destinations in response to a user selecting one...from the list; The accused devices include a means to automatically call a destination when a user selects it from the displayed list. ¶34(ii) col. 10:58-62
...means for...displaying...a list of LANs coupled to the WAN... The accused devices include a means to "display at least two directories or types of directories." ¶34(iii) col. 11:4-11
...means for displaying the first list [of destinations] in response to a user selecting one of the...LANs from the displayed list of LANs. The accused devices include a means to display the list of telephone destinations in response to a user selecting one of the directories. ¶34(iv) col. 11:32-37
  • Identified Points of Contention:
    • Scope Questions: A primary question will be whether the accused function of displaying "at least two directories or types of directories" (Compl. ¶34(iii)) meets the claim limitation of displaying "a list of LANs." The resolution will depend on whether the court construes "directory" as synonymous with or equivalent to "LAN" in the context of the patent.
    • Technical Questions: Claim 13 uses "means-plus-function" language. The infringement analysis will require the court to first identify the corresponding structure disclosed in the '298 patent's specification for performing the claimed functions (e.g., displaying, dialing) and then determine whether the accused Zoom products contain an identical or equivalent structure. The complaint's allegations are functional and do not identify the corresponding structures from the patent.

'684 Patent Infringement Allegations

Claim Element (from Independent Claim 29 and Dependent Claim 42) Alleged Infringing Functionality Complaint Citation Patent Citation
...transferring data from the workstation to the telephone, wherein the data...is addressed for transmission to the data server; The Accused Instrumentalities include workstations that transfer data through Zoom VoIP Phones with a PC port. ¶54 col. 4:39-46
...communicating audio information between the telephone and the multimedia server; The Accused Instrumentalities include VoIP servers that communicate audio information with Zoom VoIP Phones. ¶53 col. 4:13-19
...throttling the data...wherein the throttling step further comprises...monitoring an amount of the audio information being received by the telephone... The system allegedly throttles data by monitoring the audio information received by the Zoom VoIP Phone from a VoIP server. ¶55 col. 12:11-18
Additional elements for Claim 42: ...sending a throttling signal to the telephone...setting the mode level to a most aggressive mode... The VoIP server allegedly sends a throttling signal with a "mode level" set to a "most aggressive mode" after the phone sends a congestion message. ¶55; p. 12, ¶1 col. 2:50-54
...wherein the throttling step will throttle the future amount of data...at a highest level in response to the mode level being in the most aggressive mode. The system throttles data from the workstation at a "highest level" when the mode is set to the most aggressive mode. p. 12, ¶5-6 col. 2:50-54
  • Identified Points of Contention:
    • Technical Questions: The infringement case for this method claim will depend on factual evidence. A key question is whether the accused Zoom products actually perform the specific feedback loop described: does a low audio buffer on a Zoom phone in fact trigger a congestion message to a Zoom server, which in turn sends back a "mode level" signal that causes that specific phone to throttle data from a connected PC?
    • Scope Questions: The meaning of terms of degree like "most aggressive mode" and "highest level" of throttling will be a central issue. The parties will likely dispute whether the accused system's functions, even if they exist, meet the specific levels of operation described or required by the patent.

V. Key Claim Terms for Construction

For the ’298 Patent

  • The Term: "a list of LANs" (from claim 13)
  • Context and Importance: Plaintiff alleges infringement by systems that display a list of "directories." Whether a "directory" is equivalent to a "LAN" is fundamental to the infringement analysis for this claim element. Practitioners may focus on this term because the factual difference between a logical directory and a physical network is a clear point of potential dispute.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification describes organizing the system by "remote sites" and "systems" (e.g., "system 301 in Dallas"), using these terms in a way that could support an argument that any logical representation of a remote location, such as a directory, falls within the claim's scope. (’298 Patent, col. 4:60-62).
    • Evidence for a Narrower Interpretation: The claim language is specific, using the network term "LAN." The patent's figures also depict distinct, labeled "LANs," which could support a narrower construction requiring a list of explicitly identified network segments rather than just user-facing directories. (’298 Patent, Fig. 3).

For the ’684 Patent

  • The Term: "most aggressive mode" (from claim 42)
  • Context and Importance: This term of degree is critical for proving infringement of claim 42. The definition will dictate the technical evidence required to show that the accused system operates in the claimed manner. Practitioners may focus on this term because its ambiguity creates a clear path for a non-infringement defense based on a technical mismatch.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification describes the server first sending the "most aggressive value" to initiate flow control, suggesting it could refer generally to any initial, high-level throttling command without a specific numeric value. (’684 Patent, col. 2:52-54).
    • Evidence for a Narrower Interpretation: The specification provides a concrete example: "a most aggressive value may have an eighty percent duty cycle, while a least aggressive value may have a twenty percent duty cycle." (’684 Patent, col. 3:1-4). This language could be used to argue for a much narrower, quantitative definition of the term.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges both induced and contributory infringement for all asserted patents. Inducement is based on allegations that Zoom encourages and instructs its customers and partners to use the accused products in an infringing manner through advertising, user manuals, and other promotional activities. (Compl. ¶39). Contributory infringement is based on the allegation that the accused products contain special features with no substantial non-infringing use that are a material part of the inventions. (Compl. ¶40).
  • Willful Infringement: Willfulness is alleged for all asserted patents. The claims are based on Zoom's alleged knowledge of the patents at least as of the service of the original complaint, and on an allegation that Zoom maintains a policy of "willful blindness" by not reviewing the patents of others, which Plaintiff characterizes as objectively reckless conduct. (Compl. ¶41-43).

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

  • A core issue will be one of definitional scope: can the term "a list of LANs" in the ’298 patent, which suggests a display of network topology, be construed to cover the "list of...directories" allegedly displayed by the accused system? The outcome of this claim construction will be critical to the infringement analysis for that patent.
  • A second key issue will be one of technical and evidentiary proof: for the ’684 patent, does the accused Zoom QoS system actually perform the specific, multi-step feedback loop recited in the method claims? This will require detailed evidence of the internal operations of Zoom's phones and servers, particularly whether local phone congestion triggers a server-sent "mode level" signal that in turn causes data throttling.
  • Finally, a threshold question is the impact of the IPR proceeding on the '298 patent. While asserted claim 13 survived, the cancellation of 18 other claims will likely be used by the defense to argue for a narrowed interpretation of the surviving claim's scope and context, framing it as a narrow invention that they do not infringe.