DCT

2:25-cv-00305

Lemko Corp v. AT&T Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:25-cv-00305, E.D. Tex., 03/17/2025
  • Venue Allegations: Plaintiff alleges venue is proper based on Defendant AT&T Inc.'s principal place of business in Texas, the location of numerous retail stores and employees within the Eastern District of Texas, and AT&T's prior non-contestation of venue in the district for similar litigation.
  • Core Dispute: Plaintiff alleges that Defendant’s private cellular network products, particularly AT&T Private 5G Edge, infringe seven patents related to distributed mobile architecture technology.
  • Technical Context: The technology concerns a shift from traditional, centralized cellular network architectures to a decentralized model where core network functions are distributed to software-based nodes at the network's edge, aiming to reduce latency, lower costs, and improve performance.
  • Key Procedural History: The complaint alleges an extensive pre-suit history between the parties, beginning in 2013 under a non-disclosure agreement. Plaintiff claims it demonstrated its patent-practicing "Node1" products to AT&T, provided presentations and white papers identifying its patents, and engaged in dozens of meetings over a two-year period, after which AT&T allegedly used the disclosed technology to develop the accused products. These allegations form the basis for the claim of willful infringement.

Case Timeline

Date Event
2005-04-13 U.S. Patent No. 7,840,230 Priority Date
2006-06-12 U.S. Patent No. 8,224,322 Priority Date
2008-06-26 U.S. Patent No. 8,340,667 Priority Date
2008-09-25 U.S. Patent No. 7,979,066 Priority Date
2009-05-22 U.S. Patent No. 7,840,230 Application Filed
2010-11-09 U.S. Patent No. 8,310,990 Priority Date
2010-11-15 U.S. Patent No. 8,359,029 Priority Date
2010-11-23 U.S. Patent No. 7,840,230 Issued
2011-07-12 U.S. Patent No. 7,979,066 Issued
2011-12-22 U.S. Patent No. 9,198,020 Priority Date
2012-07-17 U.S. Patent No. 8,224,322 Issued
2012-11-13 U.S. Patent No. 8,310,990 Issued
2012-12-25 U.S. Patent No. 8,340,667 Issued
2013-01-22 U.S. Patent No. 8,359,029 Issued
2013-08-28 Lemko and AT&T enter into a non-disclosure agreement
2013-09-24 Lemko demonstrates patent-practicing products to AT&T
2015-11-24 U.S. Patent No. 9,198,020 Issued
2025-03-17 Complaint Filed

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

U.S. Patent No. 7,840,230 - "Communications Using A Distributed Mobile Architecture," Issued Nov. 23, 2010

The Invention Explained

  • Problem Addressed: The patent's background describes traditional cellular networks as hierarchical and circuit-switched, requiring all calls to be routed through expensive, centralized mobile switching centers (MSCs) via costly backhaul connections, even for calls between two nearby users (Compl. ¶21; ’230 Patent, col. 1:43-62). This architecture was inefficient, costly, and introduced latency (Compl. ¶21).
  • The Patented Solution: The invention proposes a "distributed mobile architecture" where core network intelligence, such as MSC and base station controller (BSC) functions, is embedded in software on smaller, decentralized servers ("DMA servers") located at the network edge (Compl. ¶22). These servers can connect in a peer-to-peer fashion, allowing local calls to be switched locally without traversing the backhaul to a central hub, thereby reducing latency and operational costs (’230 Patent, col. 3:36-50, FIG. 1).
  • Technical Importance: This decentralized approach was intended to make cellular networks faster, cheaper, and more flexible, enabling low-latency applications and private enterprise networks that were impractical under the centralized model (Compl. ¶23-24).

Key Claims at a Glance

  • The complaint asserts independent Claim 8 (Compl. ¶79).
  • Claim 8 is directed to a "communication apparatus" comprising:
    • a wireless transceiver;
    • a computer readable storage medium;
    • a home location register (HLR) module;
    • a visitor location register (VLR) module;
    • a mobile switching center (MSC) module, which includes an authentication, authorization, and accounting (AAA) module for generating call detail records;
    • a base station controller (BSC) module; and
    • a group call program to provide a group call between four or more devices, where telephony data is communicated via a second, similarly configured communication apparatus.
  • The complaint does not explicitly reserve the right to assert dependent claims for this patent.

U.S. Patent No. 7,979,066 - "Multiple IMSI Connections," Issued Jul. 12, 2011

The Invention Explained

  • Problem Addressed: The patent's background section addresses the high cost of international roaming for mobile subscribers, where calls to a roaming device are charged at expensive international rates (’066 Patent, col. 1:15-24).
  • The Patented Solution: The invention describes a system with a "multiple International Mobile Subscriber Identity (IMSI) location register (MILR) module" that stores multiple IMSI numbers and Mobile Directory Numbers (MDNs) for a single subscriber, with each set associated with a different country (’066 Patent, col. 2:1-8). The system uses "active location information" to determine which IMSI and MDN to use based on the subscriber's current country, allowing calls to be routed as local calls and avoiding international roaming charges (’066 Patent, Abstract; FIG. 1).
  • Technical Importance: This technology aims to create seamless and cost-effective international communication by making a subscriber appear as a local user in multiple different national networks (Compl. ¶38).

Key Claims at a Glance

  • The complaint asserts independent Claim 1 (Compl. ¶112).
  • Claim 1 is directed to a system comprising:
    • a first home location register module;
    • a first visitor location register module;
    • a first community location register module; and
    • a first multiple International Mobile Subscriber Identity (IMSI) location register (MILR) module that includes user information for mobile subscribers, associating a first IMSI/MDN with a first country and a second IMSI/MDN with a second country, and using active location information to activate the appropriate IMSI/MDN based on the subscriber's location.
  • The complaint does not explicitly reserve the right to assert dependent claims for this patent.

U.S. Patent No. 8,224,322 - "Roaming Mobile Subscriber Registration in a Distributed Mobile Architecture," Issued Jul. 17, 2012

  • Technology Synopsis: The patent addresses managing mobile subscriber registration as a user roams between different coverage sites within a distributed mobile architecture (DMA) network. It describes a method where a local DMA node receives a registration request and transmits the subscriber's identifier to a central visitor location register (VLR) gateway, allowing the network to track user location across different nodes (Compl. ¶139).
  • Asserted Claims: The complaint asserts at least exemplary Claim 1 (Compl. ¶139).
  • Accused Features: The accused AT&T Private 5G Edge network allegedly performs the claimed method when a mobile device moves between different coverage sites, using its unified data management (UDM) functionality to serve as the claimed VLR and VLR gateway (Compl. ¶140-146).

U.S. Patent No. 8,310,990 - "System, Method, and Device for Routing Calls Using a Distributed Mobile Architecture," Issued Nov. 13, 2012

  • Technology Synopsis: This patent relates to routing communications between different DMA gateways in a network. It describes a method where a first DMA gateway receives and stores information about a network accessible by a second DMA gateway, and then uses that information to route communications to a destination device served by that second gateway (Compl. ¶172).
  • Asserted Claims: The complaint asserts at least exemplary Claim 1 (Compl. ¶172).
  • Accused Features: The accused product's servers are alleged to function as DMA Gateways. Specifically, the User Plane Function (UPF) modules are accused of acting as interconnected gateways that receive, store, and route data between different locations in the private network (Compl. ¶174-175).

U.S. Patent No. 8,340,667 - "System and Method To Control Wireless Communications," Issued Dec. 25, 2012

  • Technology Synopsis: The patent describes a network communication system comprising a distributed mobile architecture gateway (DMAG) that interfaces with both legacy networks and a private IP network. The system includes home, visitor, and community location registers to manage subscriber information and route traffic between DMA servers across different DMAGs (Compl. ¶200).
  • Asserted Claims: The complaint asserts at least exemplary Claim 1 (Compl. ¶200).
  • Accused Features: The accused product's servers, functioning as DMAGs, allegedly contain the claimed location registers (HLR, VLR, CLR) via their UDM/UDR functionality. The system is accused of using this information to route voice traffic from a legacy network to the appropriate DMA server when a user moves between nodes (Compl. ¶203, ¶209-210).

U.S. Patent No. 8,359,029 - "System, Method, and Device for Providing Communications Using a Distributed Mobile Architecture," Issued Jan. 22, 2013

  • Technology Synopsis: The patent claims a non-transitory computer readable storage medium for a DMA system that includes AAA, HLR, and community location register (CLR) modules. The system is instructed to initiate a call between a subscriber on a first DMA system and a subscriber on a second DMA system by using the HLR and CLR information to locate the respective users (Compl. ¶232).
  • Asserted Claims: The complaint asserts at least exemplary Claim 1 (Compl. ¶232).
  • Accused Features: The accused product's software is alleged to be the claimed storage medium. The system's Push-to-Talk (PTT) feature is accused of initiating calls between subscribers on different DMA nodes (e.g., in different factories) using the system's HLR/CLR functionality (Compl. ¶233, ¶237).

U.S. Patent No. 9,198,020 - "OAMP for Distributed Mobile Architecture," Issued Nov. 24, 2015

  • Technology Synopsis: This patent is directed to a method for routing a call within a distributed architecture. It describes a process at a dMAG for receiving a call, determining a routing path based on register data, sending command messages to reserve network components (dMAG, dMA node, IP network), and connecting the call via the reserved components (Compl. ¶259).
  • Asserted Claims: The complaint asserts at least exemplary Claim 9 (Compl. ¶259).
  • Accused Features: The accused product's network is alleged to infringe by using its session management function (SMF) to establish a routing path, send requests to reserve resources (UPF functions, radio nodes), and set up user-plane tunnels to connect an incoming call (Compl. ¶265-267).

III. The Accused Instrumentality

Product Identification

  • The primary accused product is AT&T Private 5G Edge, with AT&T Private Mobile Connection also mentioned (Compl. ¶44).

Functionality and Market Context

  • The complaint describes AT&T Private 5G Edge as a private cellular network solution for enterprises that uses on-site small cells to keep data traffic local and secure (Compl. ¶47). The system can be configured with a "premise based core," which provides a private "island" of cellular service running on common-off-the-shelf (COTS) servers, such as Microsoft's Azure Stack Edge hardware (Compl. ¶48, ¶50). A network diagram provided in the complaint shows that on-site small cells connect to a "Private Network Core," which then connects to a customer's data center (Compl. p. 14). The core software, Azure Private 5G Core, is alleged to provide functions for mobility management, session handling, authentication, and data routing (Compl. ¶55). The complaint alleges these on-premise servers function as distributed mobile architecture (DMA) servers that connect with each other to form DMA networks (Compl. ¶56).

IV. Analysis of Infringement Allegations

U.S. Patent No. 7,840,230 Infringement Allegations

Claim Element (from Independent Claim 8) Alleged Infringing Functionality Complaint Citation Patent Citation
a communication apparatus, comprising: a wireless transceiver; a computer readable storage medium; AT&T's Private 5G Edge servers are alleged to be the communication apparatuses, which run on COTS servers with non-transitory computer-readable storage and are connected to wireless transceivers (RANs). ¶80-81 col. 4:5-16
a home location register (HLR) module embedded in the computer readable storage medium; The Azure Private 5G Core software allegedly includes HLR functionality through its Unified Data Management (UDM) and Unified Database Repository (UDR) components, which are described as the 5G analogs of the 2G/3G HLR. ¶83-85 col. 1:47-52
a visitor location register (VLR) module embedded in the computer readable storage medium; The software is alleged to include VLR functionality, also performed by the UDM/UDR and AUSF functions, which temporarily store information for roaming subscribers. ¶86-87 col. 1:47-52
a mobile switching center (MSC) module...[including an] authentication, authorization, and accounting (AAA) module...configured to support generation of a first set of call detail records... The software's Access and Mobility Function (AMF), Authentication Server Function (AUSF), and Unified Data Management (UDM) modules are alleged to collectively perform subscriber management and AAA functions, while the User Plane Function (UPF) and Session Management Function (SMF) perform accounting and collect charging data for call detail records. ¶88 col. 4:17-21
a base station controller (BSC) module embedded in the computer readable storage medium; The complaint alleges the Azure Private 5G Core software has BSC functionality, mapping it to the collective functions of the AMF, SMF, UDM, AUSF, and UPF modules. A diagram shows these components managing access from radio nodes (eNodeB/gNodeB). ¶88; p. 30 col. 4:17-21
a group call program...to provide a group call between four or more mobile communication devices...wherein telephony data...is communicated...via a second communication apparatus... AT&T's IP Multimedia Subsystem (IMS) allegedly supports group and conference calls. When a customer has multiple sites, each with its own Azure Private 5G Core instance (a communication apparatus), a group call can be initiated at a first site and transmitted to participants at a second site (the second communication apparatus). ¶89-90 col. 2:56-60

Identified Points of Contention:

  • Scope Questions: A primary question will be one of technological translation: do the 5G network functions identified in the complaint (e.g., UDM, UDR, AMF, SMF) meet the limitations of the 2G/3G-era terms recited in the claim (e.g., "HLR module", "MSC module", "BSC module")? The infringement theory appears to rely on arguing that these modern functions are structural or functional "analogs" to the claimed legacy components (Compl. ¶83).
  • Technical Questions: The claim requires a "group call program" for "four or more mobile communication devices." The complaint points to AT&T's general IMS capabilities (Compl. ¶89). A potential point of contention may be whether the accused product, as sold and implemented for specific enterprise customers, actually enables or is used for group calls of this size, and whether the alleged inter-site communication constitutes communication "via a second communication apparatus" as claimed.

U.S. Patent No. 7,979,066 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A system comprising: a first home location register module; a first visitor location register module; a first community location register module; The AT&T Private 5G Edge network allegedly provides a system with HLR, VLR, and community location register (CLR) functionality through its Unified Data Management (UDM) and Unified Data Repository (UDR) components. The CLR function is met by the HLR information being common between servers in different locations. ¶114 col. 2:60-65
a first multiple International Mobile Subscriber Identity (IMSI) location register (MILR) module, wherein the first MILR module includes: user information...a first IMSI number and a first Mobile Directory Number (MDN)...associated with a first country; a second IMSI number and a second MDN...associated with a second country; The UDM and UDR are alleged to hold the IMSI and MDN for each subscriber, which includes information on the SIM's country/region. The system allegedly maintains profiles that include this country-specific information. ¶116-117 col. 2:45-56
active location information, wherein when the active location information indicates that a particular mobile subscriber is located in the first country, the first IMSI number is active...and wherein when the active location information indicates that the particular mobile subscriber is located in the second country, the second IMSI number is active... The accused system is alleged to have functionality for managing a scenario where a device from one country is served by a network node in a different country, activating the IMSI and MDN associated with the country where the subscriber is currently located. ¶117 col. 2:5-8

Identified Points of Contention:

  • Scope Questions: The definition of the patentee-coined term "multiple International Mobile Subscriber Identity (IMSI) location register (MILR) module" will be critical. The dispute may center on whether the accused product's standard UDM/UDR database architecture meets the specific structural or functional requirements of this term as defined in the patent.
  • Technical Questions: A key factual question will be whether the accused product, which is marketed as a private enterprise network solution, is actually configured or used to manage subscriber identities and calls across different countries as required by the claim. The complaint makes a general allegation (Compl. ¶117), but evidence of this specific multi-country functionality in AT&T's deployed systems will be central to the dispute.

V. Key Claim Terms for Construction

For the ’230 Patent:

  • The Term: "mobile switching center (MSC) module"
  • Context and Importance: This term, rooted in legacy 2G/3G network architecture, is central to the infringement analysis. The accused product is a 5G system that does not have a traditional, monolithic MSC. Plaintiff alleges that a collection of modern 5G software functions (AMF, AUSF, UDM, SMF, UPF) collectively perform the functions of the claimed "MSC module" (Compl. ¶88). Practitioners may focus on this term because the outcome of the case could depend on whether a combination of distributed 5G microservices can be legally equated to the integrated "module" recited in the claim.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification describes the "MSC module 206" in functional terms, stating it can include a gatekeeper and various gateways (e.g., CGW, PDSN, SIP, SS7) that provide connectivity and conversion functions (’230 Patent, col. 4:20-53, FIG. 2). This functional description could support an argument that any collection of components performing these functions meets the limitation.
    • Evidence for a Narrower Interpretation: The patent figures depict the "MSC Functionality" as a discrete block within the "DMA Server" architecture (’230 Patent, FIG. 2). A defendant may argue that this depiction requires the claimed functions to be part of a singular, co-located software "module," rather than distributed across multiple, independent 5G network functions as alleged in the complaint.

For the ’066 Patent:

  • The Term: "active location information"
  • Context and Importance: This term is critical because it is the input that triggers the claimed system's core function: switching between different country-specific IMSIs. The dispute will likely involve what type of location data qualifies and how "active" it must be. Practitioners may focus on this term because its construction will determine what evidence Plaintiff must produce to show that the accused system actually performs the claimed multi-country switching.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification states that the MILR includes "active location information related to each mobile subscriber" and that this information "records information related to a current location of a particular mobile subscriber" (’066 Patent, col. 2:60-62). This could be read broadly to cover any data indicating a subscriber's current location, such as the network node to which they are connected.
    • Evidence for a Narrower Interpretation: The detailed embodiments may link the "active location information" to a specific registration event or a flag in a specific database field (e.g., ’066 Patent, FIG. 7, element 734). A defendant could argue for a narrower definition tied to these specific implementations, potentially requiring more than just general network attachment information.

VI. Other Allegations

Indirect Infringement

  • The complaint alleges that AT&T induces infringement by instructing and encouraging its customers to install and use the AT&T Private 5G Edge product in an infringing manner. This is allegedly accomplished through promotional materials, user guides, support contracts, and by directing customers to purchase a specific bill of materials (hardware servers, RANs, SIMs) to combine with AT&T's software (Compl. ¶98-101). The complaint further alleges contributory infringement, stating the software has no substantial non-infringing use because its only function is to provide the core infringing functionalities when operated as a node in a mobile network (Compl. ¶104).

Willful Infringement

  • The willfulness allegations are based on extensive pre-suit knowledge alleged to date back to at least 2013. The complaint asserts that Lemko disclosed its technology and its patent portfolio to over 100 AT&T officers and engineers during dozens of meetings, provided patent-marked hardware for demonstration, and sent white papers and emails listing the asserted patents, all before AT&T allegedly began developing its infringing products (Compl. ¶57-73).

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

  • A core issue will be one of technological translation: can the functions of AT&T's modern, disaggregated 5G private network core (e.g., UDM, AMF, UPF) be mapped onto the 2G/3G-era components explicitly recited in the asserted patent claims (e.g., "HLR module", "MSC module"), or is there a fundamental mismatch in technical operation and structure that precludes a finding of infringement?
  • A key evidentiary question will be one of factual use: for patents like the ’066 patent that claim multi-country functionality, what evidence will show that AT&T's Private 5G Edge products—marketed for domestic enterprise use—are actually configured and used to manage subscriber identities and route calls across international borders as the claims require?
  • A central issue for damages will be willfulness: given the detailed allegations of AT&T's multi-year evaluation of Lemko's patented and patent-marked technology prior to developing the accused products, the court will have to determine whether any infringement was willful, which could lead to an award of enhanced damages.