Lemko Corp v. Microsoft Corp

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Lemko Corporation (Illinois)
  • Defendant: Microsoft Corporation (Washington)
  • Plaintiff's Counsel: Kane Russell Coleman Logan
• Case Identification: 3:26-cv-01876, N.D. Tex., 06/05/2026
• Venue Allegations: Venue is alleged to be proper in the Northern District of Texas because Microsoft maintains a regular and established place of business in Irving, Texas.
• Core Dispute: Plaintiff alleges that Defendant's Azure cloud and edge computing products for telecommunications operators infringe four patents related to distributed mobile network architectures.
• Technical Context: The technology at issue is multi-access edge computing (MEC) and distributed mobile architecture (DMA), which involve decentralizing mobile network processing from a central core to the network "edge," closer to the end-user, to improve speed and efficiency.
• Key Procedural History: The complaint alleges that the same parties are currently in litigation over the same patents asserted against different Microsoft products. Plaintiff also alleges providing a pre-suit notice letter to Microsoft. U.S. Patent No. 7,653,414 survived an Inter Partes Review (IPR) proceeding (IPR2023-00529), with the USPTO confirming the patentability of asserted claims, which may strengthen their presumption of validity.

Case Timeline

Date	Event
2004-01-01	Lemko Corporation founded
2006-02-24	U.S. Patent No. 7,653,414 Priority Date
2006-03-30	U.S. Patent No. 8,688,111 Priority Date
2008-04-23	U.S. Patent No. 9,191,980 Priority Date
2008-07-14	U.S. Patent No. 9,332,478 Priority Date
2010-01-26	U.S. Patent No. 7,653,414 Issued
2010-01-01	Metaswitch-Lemko discussions under NDA begin (approx.)
2014-04-01	U.S. Patent No. 8,688,111 Issued
2015-11-17	U.S. Patent No. 9,191,980 Issued
2016-05-03	U.S. Patent No. 9,332,478 Issued
2017-01-01	Microsoft-Lemko partnership discussions begin (approx.)
2020-07-01	Microsoft acquires Metaswitch Networks
2022-02-14	"Microsoft I" complaint filed
2023-02-15	IPR filed against U.S. Patent No. 7,653,414
2024-12-20	IPR Certificate issued for U.S. Patent No. 7,653,414
2026-04-22	Lemko sends pre-suit notice letter to Microsoft
2026-06-05	Complaint Filing Date

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

U.S. Patent No. 7,653,414 - "System, Method, and Device for Providing Communications Using a Distributed Mobile Architecture," Issued Jan. 26, 2010

The Invention Explained

• Problem Addressed: The patent's background section describes that conventional telephone systems are expensive to deploy, particularly in rural and isolated areas, due to their reliance on centralized and costly hardware like a mobile switching center (MSC) and base station controller (BSC) US7653414B2, col. 1:11-48
• The Patented Solution: The invention proposes a "distributed mobile architecture" (DMA) where network logic is decentralized into smaller, software-based servers that can be deployed at the network edge and connected via peer-to-peer IP networks US 7,653,414 B2, col. 3:56-4:14 A key component is a "destination preference register" (DPR) within an authentication, authorization, and accounting (AAA) module, which stores preferred call paths for routing calls to destinations outside the local DMA network US 7,653,414 B2, abstract US 7,653,414 B2, col. 8:31-40
• Technical Importance: This architecture aimed to lower the economic barrier for extending cellular coverage to underserved communities by replacing expensive, specialized hardware with a more scalable and resilient software-based approach Compl. ¶31

Key Claims at a Glance

• The complaint asserts at least independent Claim 11 Compl. ¶72
• The essential elements of Claim 11 are:
  • A distributed mobile architecture (DMA) system, comprising a housing and a base transceiver station.
  • A computer-readable storage medium within the housing.
  • The medium comprises an authentication, authorization, and accounting (AAA) module, which in turn comprises:
    • a home location register (HLR) for subscribers registered with the DMA system;
    • a visitor location register (VLR) for temporarily roaming subscribers;
    • a community location register (CLR) that stores information associated with a second HLR of a second DMA system; and
    • a destination preference register (DPR) that stores preferred call paths for calls to be routed outside the DMA network.
  • A call routing component to route a call via a preferred path from the DPR when the AAA module determines the call is for a destination outside the DMA network.
• The complaint does not explicitly reserve the right to assert dependent claims but does not limit its allegations to Claim 11.

U.S. Patent No. 8,688,111 - "System, Method, and Device for Providing Communications Using a Distributed Mobile Architecture," Issued Apr. 1, 2014

The Invention Explained

• Problem Addressed: As with its parent, the '111 patent addresses the high cost and centralization of conventional cellular networks, which are ill-suited for rural deployment US8688111B2, col. 1:29-51
• The Patented Solution: The invention is a method for connecting a call between two mobile subscribers in a multi-system DMA network. The method involves a first DMA system receiving a call and determining if the destination subscriber is registered with the first or a second DMA system. This determination is based on information in an AAA module that includes a home location register (HLR) for the first system and a community location register (CLR) containing information about the second system's HLR. The connection is then initiated between the two DMA systems US 8,688,111 B2, abstract US 8,688,111 B2, col. 5:1-24
• Technical Importance: This method provides a mechanism for interoperability and seamless call routing between distinct decentralized network clusters, which is crucial for building a scalable and resilient distributed mobile network Compl. ¶¶31-33

Key Claims at a Glance

• The complaint asserts at least independent Claim 15 Compl. ¶107
• The essential elements of Claim 15 are:
  • A method comprising receiving a call at a first DMA system from a first mobile subscriber to a second.
  • Determining if the second subscriber is registered with the first or a second DMA system, based on information in an AAA module.
  • The AAA module includes a first HLR (for the first DMA system) and a first CLR (storing information about a second HLR of the second DMA system).
  • Initiating the connection of the call via both the first and second DMA systems when the second subscriber is registered with the second DMA system.
• The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 9,191,980 - "System and Method to Control Wireless Communications," Issued Nov. 17, 2015

• Technology Synopsis: The patent discloses a method for routing a call that originates at a first DMA server but is destined for a device outside that server's wireless coverage area Compl. ¶146 The method uses a "distributed mobile architecture gateway" (DMAG) to support communication with the destination, which involves converting voice information into packet data and routing it via the DMAG '980 Patent, abstract
• Asserted Claims: At least Claim 1 Compl. ¶141
• Accused Features: The complaint alleges that Azure Operator Nexus infringes by using its User-Plane Function (UPF) as a DMAG equivalent to convert voice calls to packet data and route them to external networks Compl. ¶¶151-154

U.S. Patent No. 9,332,478 - "System, Method, and Device for Routing Calls Using a Distributed Mobile Architecture," Issued May 3, 2016

• Technology Synopsis: The patent discloses a method within a "DMA gateway communications network" for routing communications between different DMA gateways associated with different groups of DMA servers Compl. ¶179 The method involves a first gateway transmitting communications information to a second gateway, and subsequently receiving a communication from that second gateway destined for a device accessible to the first gateway '478 Patent, abstract
• Asserted Claims: At least Claim 1 Compl. ¶174
• Accused Features: The complaint alleges that Azure Operator Nexus's use of interconnected User-Plane Function (UPF) modules, which act as DMAGs, to route communications between different network segments infringes the '478 Patent Compl. ¶¶183-184

III. The Accused Instrumentality

• Product Identification: The complaint identifies Microsoft's Azure Operator Nexus, Azure Operator Edge, Azure MEC, and Azure Programmable Connectivity (APC) as the "Accused Products" Compl. ¶52 The infringement allegations focus primarily on the functionality of Azure Operator Nexus, both alone and in combination with the other products.
• Functionality and Market Context: The Accused Products are described as a "carrier-grade" platform enabling telecommunications operators to build and manage decentralized and virtualized mobile networks Compl. ¶53 The platform uses commercially available off-the-shelf (COTS) servers to run virtualized network functions (VNFs) and containerized network functions (CNFs) at various locations, including on-premises "edge" sites close to the user Compl. ¶¶56-57 The complaint alleges these products are sold to major telecom operators and represent a modern implementation of the distributed architecture principles disclosed in the patents-in-suit Compl. ¶49 Compl. ¶51 The complaint includes a diagram illustrating how Microsoft's "Azure for Operators Portfolio" positions Azure Operator Nexus as the core carrier-grade platform Compl. p. 14

IV. Analysis of Infringement Allegations

7,653,414 Infringement Allegations

Claim Element (from Independent Claim 11)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A distributed mobile architecture (DMA) system, comprising: a housing;	Azure Operator Nexus provides the software and hardware infrastructure and supports a single rack Bill of Materials (BOM), constituting the housing.	¶78; ¶79	col. 6:7-10
a base transceiver station coupled to the housing...operable to receive a call...	The system includes CU/DU/RAN transceiver equipment that provides the functionality of a base transceiver station.	¶81	col. 7:20-25
a computer readable storage medium within the housing...	The DMA system provides network functions (UPF, SMF, AMF, etc.) as software components on a computer-readable storage medium.	¶80	col. 6:7-9
an authentication, authorization, and accounting (AAA) module...	The system uses a combination of 5G functions (UDR, PCF, UDM, AUSF, etc.) to provide AAA functionality.	¶83	col. 7:1-3
a home location register (HLR) that stores information associated with one or more mobile subscriber devices...	The roles of the HLR are handled by the Unified Data Management (UDM) and Unified Data Repository (UDR) network functions.	¶86	col. 8:7-15
a visitor location register (VLR) that stores information associated with one or more roaming mobile subscriber devices...	The UDM and UDR also provide VLR functionality.	¶86	col. 8:4-6
a community location register (CLR) that stores information associated with a second HLR of a second DMA system...	The HLR (UDR/UDM) is common across different 5G Core instances, causing it to function as a CLR. The UPF routing table also operates as a CLR by storing IP addresses for other systems.	¶87	col. 8:16-24
a destination preference register (DPR) that stores one or more preferred call paths for calls to be routed outside of a DMA network...	The Session Management Function (SMF) stores a PDU network-choice configuration in its local data store, which functions as a DPR.	¶88	col. 8:31-40
a call routing component...to route the call via a particular preferred call path...stored at the DPR...	The User-Plane Function (UPF), when designated as the PDU Session Anchor by the SMF, contains the routing instructions to route the call to an outside network. The complaint includes a demonstrative diagram illustrating this data flow Compl. p. 34	¶89	col. 19:10-20

• Identified Points of Contention:
  • Scope Questions: A central question for claim construction will be whether the patent's 2G/3G-era terms like "home location register (HLR)", "community location register (CLR)", and "destination preference register (DPR)" can be construed to read on the collection of modern, disaggregated 5G network functions ("UDM", "UDR", "UPF routing table", "SMF data store") that the complaint alleges perform these roles. The defense may argue that a collection of separate functions does not meet the limitation of a single named register (e.g., "a...register").
  • Technical Questions: The complaint alleges that multiple distinct 5G network functions (e.g., UDR, PCF, UDM, AUSF) collectively provide the functionality of the claimed "AAA module". The court will need to evaluate whether this combination of functions, operating across different planes of the network, constitutes the single, integrated "module" as described and claimed in the patent.

8,688,111 Infringement Allegations

Claim Element (from Independent Claim 15)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
receiving at a first distributed mobile architecture (DMA) system, a call from a first mobile subscriber to a second mobile subscriber;	The Access and Mobility Management Function (AMF) in the first DMA system receives connection and session information for a call from a user equipment (UE).	¶115; ¶118	col. 5:1-4
determining whether the second mobile subscriber is registered with one of the first DMA system and a second DMA system based on information stored at an authentication, authorization, and accounting (AAA) module...	The system determines subscriber registration status using AAA functionality provided by modules such as AMF, PCF, UDR, AuSF, and UDM.	¶116	col. 5:5-9
wherein the information stored at the AAA module includes: a first home location register (HLR)...	The roles of the HLR are handled by the Unified Data Management (UDM) and Unified Data Repository (UDR) network functions.	¶121	col. 5:10-12
and a first community location register (CLR) storing information associated with a second HLR of the second DMA system...	Because the HLR (UDR/UDM) is common across different 5G Core instantiations, it functions as a Community Location Register (CLR) by holding information about subscribers across systems.	¶122	col. 5:13-19
initiating connection of the call...via the first DMA system and the second DMA system when the second mobile subscriber is registered with the second DMA system.	Once the destination is determined, the Session Management Function (SMF) in each system configures the User-Plane Functions (UPFs) to establish a user-plane path between the systems, connecting the call. The complaint includes a diagram illustrating this inter-system call flow Compl. p. 46	¶124	col. 5:20-24

• Identified Points of Contention:
  • Scope Questions: As with the '414 patent, a primary dispute will likely be whether the patent's architectural terms ("DMA system", "AAA module", "HLR", "CLR") can be mapped to the accused Azure platform's architecture, which is based on a more recent and disaggregated 5G standard.
  • Technical Questions: For this method claim, a key question will be whether the accused system's process of using an SMF to configure UPFs to establish a data path between two separate systems constitutes "initiating connection of the call... via the first DMA system and the second DMA system" as recited. The defense may argue this is merely data forwarding, not the integrated call connection initiation contemplated by the patent.

V. Key Claim Terms for Construction

For U.S. Patent 7,653,414

• The Term: "community location register (CLR)"
• Context and Importance: This term is critical because the patent claims a system with discrete registers (HLR, VLR, CLR). The complaint alleges this limitation is met by a combination of a shared database (UDR/UDM) and a routing table within a User-Plane Function (UPF) Compl. ¶87 The viability of the infringement case may depend on whether this functional mapping is permissible under the claim's scope.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The specification describes the CLR functionally as storing information "associated with one or more mobile subscribers registered with the second distributed mobile architecture system" US 7,653,414 B2, col. 19:1-5 Plaintiff may argue that the UPF routing table, which stores IP addresses for devices in other systems, fulfills this function.
  • Evidence for a Narrower Interpretation: The patent figures depict the CLR as a distinct database-like entity within an AAA module, alongside the HLR and VLR US 7,653,414 B2, FIG. 4, item 410 US 7,653,414 B2, FIG. 5 A defendant may argue that this implies a control-plane database structure, not a user-plane routing table, and that the CLR is explicitly part of the claimed "AAA module", whereas the accused UPF is a separate network function.

For U.S. Patent 8,688,111

• The Term: "initiating connection of the call"
• Context and Importance: This method step is the culmination of the claim. The complaint alleges this step is met when an SMF configures UPFs to create a data path between two systems Compl. ¶124 Practitioners may focus on this term because its construction will determine whether configuring a data forwarding path is equivalent to the affirmative act of "initiating connection."
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The specification describes the outcome as connecting a call "via the first DMA and the second DMA" US 8,688,111 B2, col. 9:60-63 Plaintiff may argue that any steps that result in this end-to-end connection, including configuring a data path, satisfy the "initiating" requirement.
  • Evidence for a Narrower Interpretation: The patent flowcharts show "First DMA connects call" as a discrete step US 8,688,111 B2, FIG. 7, step 710, which could imply a singular, affirmative action rather than a series of configuration commands. A defendant may argue that "initiating connection" requires a specific signaling event distinct from simply programming a data forwarding rule.

VI. Other Allegations

• Indirect Infringement: The complaint alleges both induced and contributory infringement for all four asserted patents. For inducement, it alleges Microsoft instructs and encourages customers to deploy and use the Accused Products in an infringing manner through documentation, "How-To Guides," "Quickstarts," and tutorials Compl. ¶¶99-102 Compl. ¶¶133-136 For contributory infringement, it alleges the Azure Operator Nexus software is not a staple article of commerce and has no substantial non-infringing use when deployed in a mobile network Compl. ¶103 Compl. ¶137
• Willful Infringement: The complaint alleges willful infringement based on extensive pre-suit knowledge. The allegations include knowledge from prior litigation on the same patents ("Microsoft I") beginning in 2022 Compl. ¶39, knowledge obtained through Microsoft's acquisition of Metaswitch Networks, whose employees had evaluated Lemko's technology under an NDA Compl. ¶41, direct partnership discussions between Microsoft and Lemko in 2017 Compl. ¶42, and a specific notice letter sent on April 22, 2026 Compl. ¶45 The complaint also points to Lemko's patent-marked products as a source of notice and provides a photo of a product label listing the asserted patents Compl. p. 10

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

1. Definitional Scope: A core issue will be one of definitional scope: can the patent terms rooted in 2G/3G mobile architecture (e.g., "HLR", "CLR", "DPR", "AAA module") be construed to encompass the disaggregated, virtualized, and functionally distinct components of Microsoft's modern 5G-based cloud platform (e.g., "UDM", "UDR", "SMF", "UPF")?
2. Architectural Equivalence: A key evidentiary question will be whether the accused Azure platform, which distributes network logic across numerous independent software functions, constitutes the more integrated "distributed mobile architecture (DMA) system" claimed in the patents, or if there is a fundamental mismatch in technical architecture that places the accused products outside the claim scope.
3. Willfulness and Intent: Given the detailed allegations of a long history of interaction between the parties, including prior litigation, partnership discussions, and employee overlap, a central question for trial will be Microsoft's state of mind. The court will need to determine whether the alleged infringement, if found, was willful, which could have significant implications for potential damages.