DCT
6:22-cv-00076
Marble VoIP Partners LLC v. Microsoft Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Marble VOIP Partners LLC (Texas)
- Defendant: Microsoft Corporation (Washington)
- Plaintiff’s Counsel: Folio Law Group PLLC; Goldberg Segalla LLP
- Case Identification: 6:22-cv-00076, W.D. Tex., 01/20/2022
- Venue Allegations: Venue is alleged to be proper based on Microsoft maintaining regular and established places of business within the Western District of Texas, conducting business in the district, and having been subject to prior patent litigation in the same venue.
- Core Dispute: Plaintiff alleges that Defendant’s Microsoft Teams and Skype for Business platforms infringe a patent related to integrating Voice over Internet Protocol (VoIP) capabilities as a system-level service accessible by various computer applications.
- Technical Context: The technology concerns a framework for decoupling Session Initiation Protocol (SIP) functionality from individual applications and making it a uniform, system-wide service, aiming to improve efficiency and enable new integrations between voice and data applications.
- Key Procedural History: The complaint alleges that the patent-in-suit was originally assigned to IBM. It also alleges that the patent followed a series of related patents that were previously licensed to Microsoft. Plaintiff sent a notice letter regarding the alleged infringement to Microsoft’s CEO, which was received on the same day the complaint was filed.
Case Timeline
| Date | Event |
|---|---|
| 2002 | Microsoft allegedly established business in district |
| 2003-10-29 | ’129 Patent Priority Date (Application Filing) |
| 2008-05-20 | ’129 Patent Issue Date |
| 2022-01-19 | Notice letter sent to Microsoft |
| 2022-01-20 | Notice letter received by Microsoft |
| 2022-01-20 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,376,129 - Enabling Collaborative Applications Using Session Initiation Protocol (SIP) Based Voice Over Internet Protocol Networks (VOIP), issued May 20, 2008
The Invention Explained
- Problem Addressed: The patent identifies a problem in the prior art where applications wanting to use VoIP, such as instant messaging clients or softphones, had to bundle their own separate support for Session Initiation Protocol (SIP). This approach was described as wasteful of system resources and created conflicts when multiple applications tried to use the same network port (Compl. ¶¶26-27; ’129 Patent, col. 1:28-37). This siloing of functionality prevented a uniform method for desktop applications to invoke SIP-based services (’129 Patent, col. 1:38-40).
- The Patented Solution: The invention proposes a framework to make SIP a "recognizable protocol at a system level" with a corresponding protocol handler available to all applications on the system (Compl. ¶28; ’129 Patent, col. 2:32-38). Instead of each application running its own SIP stack, a centralized SIP service is made available through an Application Programming Interface (API). Applications can then invoke VoIP functions, for instance, by presenting a user with a clickable "SIP link" that, when selected, calls the system-level SIP service (’129 Patent, Abstract). Figure 1 of the patent illustrates this architecture, showing various applications (e.g., Web Browser 41, IM Agent 43) interfacing with a central "SIP Wrapper Utility" 42.
- Technical Importance: This centralized framework is asserted to reduce delays in setting up voice calls, enhance system efficiency, and allow applications to use "native SIP capabilities" that might be lost when additional software layers are injected between applications and the SIP protocol (Compl. ¶29).
Key Claims at a Glance
- The complaint asserts independent claim 22 and reserves the right to assert claims 1-31 (Compl. ¶45, ¶59).
- Independent Claim 22 is directed to a program storage device with instructions to perform a method comprising the following essential elements:
- registering session initiation protocol (SIP) as a system service;
- providing SIP service through an application programming interface (API) to permit access to service functions by individual software applications by recognizing SIP links within the application and highlighting the SIP link in a user interface of the application to permit users to select the SIP links to enable voice over Internet service within the software application; and
- passing the link as a parameter to permit external access to an invoked service function to provide voice communication capabilities for the software application.
- The complaint reserves the right to assert additional claims (Compl. ¶59, ¶76).
III. The Accused Instrumentality
Product Identification
- Microsoft Teams and Microsoft Skype for Business (Compl. ¶15).
Functionality and Market Context
- The complaint alleges that both Microsoft Teams and Skype for Business are software platforms that make and receive VoIP calls for computer applications (Compl. ¶37, ¶39).
- The core accused functionality is that both platforms allegedly "register SIP as a system service to handle inbound and outbound calls" (Compl. ¶37, ¶39). For Teams, this is allegedly accomplished through a "SIP gateway" (Compl. ¶49), while for Skype for Business, SIP is described as a "required front-end server component for VoIP" (Compl. ¶66).
- The complaint alleges Skype for Business is "fully integrated within Microsoft Outlook" (Compl. ¶62). The platforms are alleged to use APIs, such as the Microsoft Graph API for Teams, to provide their communication functions (Compl. ¶50). A Microsoft support webpage showing how to "Set up an online meeting in Outlook" is cited to show a link is passed as a parameter (Compl. ¶51, ¶68, Ex. 9).
IV. Analysis of Infringement Allegations
’129 Patent Infringement Allegations (Claim 22)
| Claim Element (from Independent Claim 22) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for enabling voice over Internet for computer applications... | Microsoft Teams and Skype for Business are software platforms that provide VoIP services. | ¶48, ¶65 | col. 11:38-44 |
| registering session initiation protocol (SIP) as a system service; | Microsoft Teams allegedly uses a "SIP gateway" and Skype for Business allegedly uses SIP as a "required front-end server component." Both allegedly register SIP as a service, evidenced by online documentation and URL association settings. | ¶49, ¶66 | col. 11:45-47 |
| providing SIP service through an application programming interface (API) to permit access... by recognizing SIP links within the application and highlighting the SIP link in a user interface... to permit users to select the SIP links to enable... service... | Microsoft provides the Microsoft Graph API for Teams and the Skype for Business App SDK to allow access to communications functions. A Microsoft developer documentation webpage titled "Working with the communications API in Microsoft Graph" is provided as evidence (Compl. ¶50, Ex. 8). | ¶50, ¶67 | col. 11:48-58 |
| passing the link as a parameter to permit external access to an invoked service function to provide voice communication capabilities for the software application. | Functionality is allegedly evidenced by Microsoft support guides describing how users set up online meetings in Outlook, which generates a link for the meeting. | ¶51, ¶68 | col. 11:59-63 |
Identified Points of Contention
- Scope Questions: A primary issue may be whether the accused products' use of a "SIP Gateway" (for Teams) or server components and APIs constitutes "registering session initiation protocol (SIP) as a system service" as claimed. The patent specification discusses registration within an operating system's common registry, such as the Windows Registry (’129 Patent, col. 6:56-col. 7:4). The dispute may center on whether the claim term "system service" is limited to this specific OS-level implementation or can be read more broadly to cover the cloud-based gateway and API architecture alleged by the plaintiff.
- Technical Questions: The complaint alleges infringement of the "recognizing SIP links within the application" limitation by citing API documentation and Outlook integration. A potential question for the court is what factual evidence demonstrates that the accused products actively "recognize" and "highlight" links in the manner described by the patent, which provides examples such as an IM client parsing chat messages for text matching a specific URI format (’129 Patent, col. 8:60-65).
V. Key Claim Terms for Construction
The Term: "system service"
- Context and Importance: The construction of this term is fundamental to the infringement analysis. The case may turn on whether Microsoft's architecture, which relies on gateways and APIs, falls within the scope of a "system service." Practitioners may focus on this term because the patent’s specific examples differ from the modern cloud-based architecture of the accused products.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent's summary states that "SIP is made a recognizable protocol at a system level along with a protocol handler that is considered a system service available to all applications on the system" (’129 Patent, col. 2:32-36). Plaintiff may argue this supports a functional definition, where any implementation making SIP universally available to other applications qualifies.
- Evidence for a Narrower Interpretation: The detailed description provides a specific example of implementation: "registering a SIP protocol handler" with "operating systems like WINDOWS®, which have a single common registry of protocols like http, ftp etc." (’129 Patent, col. 6:56-62). Defendant may argue this language limits the term to a direct, OS-level registration.
The Term: "recognizing SIP links within the application"
- Context and Importance: This term defines the mechanism for invoking the SIP service. The dispute will likely involve whether the accused products' functionality meets this limitation, or if there is a mismatch in technical operation.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent describes making "SIP URLs ('links') ... recognizable within each application" and "highlighted in the user interface" to allow users to click them (’129 Patent, col. 7:15-20). Plaintiff could argue that any process that renders a SIP-based URI as an actionable, clickable hyperlink within a program (like Outlook) meets this limitation.
- Evidence for a Narrower Interpretation: A specific example in the patent describes an IM client that "parses the chat messages for potential SIP URIs and on detecting any text that matches the sip:conference-name@conference-server-domain form, it recognizes it as a SIP URI" (’129 Patent, col. 8:60-65). Defendant may argue this points to a more specific requirement of active parsing and pattern-matching, rather than simply generating a pre-formatted link.
VI. Other Allegations
- Indirect Infringement: The complaint alleges induced infringement under 35 U.S.C. § 271(b). The factual basis is Microsoft's alleged provision of the Teams and Skype for Business platforms along with "directions instructing users how to use" them in a manner that directly infringes, such as through support documentation and user guides (Compl. ¶45, ¶62, ¶53-56).
- Willful Infringement: The complaint alleges that Microsoft had knowledge of the ’129 Patent at least as of January 20, 2022, the date it received a notice letter from Plaintiff (Compl. ¶54, ¶71). The willfulness claim appears to be based on Microsoft’s alleged continued infringement after receiving this notice. The complaint also notes that other patents in the same family were "previously licensed to Microsoft," a fact which could be argued to support earlier awareness of the technology area (Compl. ¶24).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope: can the term "system service," which the patent describes in the context of an operating system registry, be construed to cover the accused products' architecture of cloud-based gateways and application programming interfaces?
- A key evidentiary question will be one of technical implementation: does the generation and embedding of a meeting link within Microsoft Outlook or Teams constitute "recognizing SIP links within the application," or does the patent require a more specific function of actively parsing and identifying URIs from user-generated text?
- The case will also examine knowledge and intent, focusing on whether Microsoft's alleged continued conduct after receiving a notice letter, potentially contextualized by an alleged prior license to a related patent family, rises to the level of willful infringement.