DCT
6:20-cv-00458
WSOU Investments LLC v. Microsoft Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: WSOU Investments, LLC d/b/a Brazos Licensing and Development (Delaware)
- Defendant: Microsoft Corporation (Washington)
- Plaintiff’s Counsel: Etheridge Law Group, PLLC
- Case Identification: 6:20-cv-00458, W.D. Tex., 06/02/2020
- Venue Allegations: Plaintiff alleges venue is proper in the Western District of Texas because Microsoft has maintained regular and established places of business in the district since at least 2002, including corporate sales offices, retail stores, and data centers in Austin and San Antonio. The complaint also notes that the district has been deemed a proper venue for other patent cases against Microsoft.
- Core Dispute: Plaintiff alleges that Defendant’s Skype for Business Server, specifically its Enterprise Voice services, infringes a patent related to providing continued local call routing functionality during a network failure.
- Technical Context: The technology addresses maintaining telecommunications service continuity in packet-based networks, particularly for enterprise systems where a branch office might lose its primary connection to a central controller.
- Key Procedural History: The complaint does not mention any prior litigation, Inter Partes Review (IPR) proceedings, or licensing history concerning the patent-in-suit. It does reference other patent cases filed against Microsoft in the district to support its venue allegations.
Case Timeline
| Date | Event |
|---|---|
| 2002-12-17 | ’868 Patent Priority Date |
| 2008-06-17 | ’868 Patent Issue Date |
| 2020-06-02 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,388,868 - Call-Routing Apparatus, and Associated Method, for Providing Local Call Handling Functions in a Communication Network
The Invention Explained
- Problem Addressed: In modern telecommunication systems, call control is often centralized in a "softswitch." If the communication link between a local access gateway (e.g., at a branch office) and this central softswitch fails, the patent asserts that even calls made entirely within the local network cannot be completed, as they lack the necessary control instructions from the unavailable softswitch (’868 Patent, col. 2:59-65, col. 3:1-4).
- The Patented Solution: The invention proposes an "emergency call router" that detects the failure of the primary communication link. Upon detection, this router becomes active to provide "rudimentary local call handling functions," enabling the completion of local-to-local calls. It can also reroute high-priority calls, such as an emergency call intended for a remote dispatch center, to a designated local station, ensuring a level of service continuity despite the network outage (’868 Patent, Abstract; col. 3:55-62). The apparatus (48) is depicted in Figure 1 as being coupled to an access gateway (16-1).
- Technical Importance: The described solution provides a failover mechanism to preserve essential voice services at a local level during a wide area network (WAN) outage, a critical reliability feature for enterprise and institutional users (’868 Patent, col. 3:5-10).
Key Claims at a Glance
- The complaint asserts infringement of at least independent claim 1 (Compl. ¶32).
- The essential elements of independent claim 1 include:
- An "emergency call router" that is coupled to an access gateway and becomes operable in response to a "failure of the normal-operation communication link."
- The emergency call router routes a call of a "first selected call-type."
- A "target gateway" that is coupled to the emergency call router.
- The emergency call router "determines whether the call request is for a call of the first selected call-type prior to" routing the call.
- The complaint does not explicitly reserve the right to assert dependent claims.
III. The Accused Instrumentality
Product Identification
The "Accused Products" are identified as "voice telephony services, including Enterprise Voice services on Microsoft Skype for Business Server" (Compl. ¶23).
Functionality and Market Context
The complaint alleges that Skype for Business Server provides a "voice resiliency" feature for branch sites in the event the wide area network (WAN) connection to a central site becomes unavailable (Compl. ¶25). This feature relies on a "Survivable Branch Appliance" or "Survivable Branch Server" which allows users at the branch site to continue making and receiving calls (Compl. ¶25). During such a WAN failure, the complaint states that the Survivable Branch Appliance redirects calls, including emergency 911 calls, to a local Public Switched Telephone Network (PSTN) gateway, thereby providing "uninterrupted voice service" (Compl. ¶¶ 25, 27-28). The complaint includes a screenshot from Microsoft documentation describing this voice resiliency functionality. This visual, located on page 6 of the complaint, explains that in the event of a WAN failure, "branch site calls must be redirected to a local PSTN gateway" (Compl. p. 6). The complaint also references a visual from a Microsoft office locator to support its venue allegations by showing Microsoft's physical locations in the district (Compl. p. 3).
IV. Analysis of Infringement Allegations
’868 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| an emergency call router at least coupled to the access gateway, said emergency call router selectably operable responsive to failure of the normal-operation communication link for routing the call of the first selected call-type... | The "Survivable Branch Appliance" or "Survivable Branch Server" provides "voice resiliency" and becomes operational to handle calls when the WAN connection between a branch site and a central site fails. | ¶¶ 25, 27 | col. 9:17-25 |
| a target gateway coupled to the emergency call router; | During a WAN failure, the Survivable Branch Appliance routes calls, including emergency calls, to a "local branch gateway" or "local PSTN gateway." | ¶¶ 25, 28, 30 | col. 9:26-27 |
| said emergency call router determines whether the call request is for a call of the first selected call-type prior to said operation of routing the call of the first selected call-type. | The Survivable Branch Appliance routes emergency calls (e.g., 911) to the local gateway, and administrators can create "dialing plans and voice policies" and "normalization and translation rules" to correctly route different types of calls during an outage. | ¶¶ 28, 29, 31 | col. 9:28-33 |
- Identified Points of Contention:
- Scope Questions: A potential dispute may arise over whether Microsoft's "Survivable Branch Appliance"—a software-based resiliency feature—is structurally equivalent to the "emergency call router" described in the patent, which the specification and figures arguably depict as a distinct apparatus (’868 Patent, Fig. 1).
- Technical Questions: The complaint alleges the "local branch gateway" is the claimed "target gateway." A key question will be whether the alleged act of "routing" a call to this gateway satisfies the claim requirement that the target gateway be "coupled to" the emergency call router. The definition of "coupled to" may be a central point of dispute.
- Technical Questions: Claim 1 requires that the determination of the call-type occurs "prior to" the routing operation. The complaint describes the existence of routing policies and rules but does not provide specific evidence detailing the precise operational sequence of this determination relative to the act of routing in the accused system.
V. Key Claim Terms for Construction
The Term: "emergency call router"
- Context and Importance: This term is the central component of the invention. Its construction will determine whether a software-based "resiliency mode" like the accused "Survivable Branch Appliance" falls within the scope of the claims, or if the claims are limited to a more distinct piece of hardware.
- Intrinsic Evidence for a Broader Interpretation: The claim language is functional, defining the element by what it does: "an emergency call router ... operable ... for routing the call" (’868 Patent, col. 9:17-22). This may support an interpretation covering any component, whether hardware or software, that performs the recited function.
- Intrinsic Evidence for a Narrower Interpretation: The detailed description repeatedly refers to the invention as an "apparatus" and depicts it in Figure 1 as a discrete block (48), separate from the access gateway (16-1). The abstract also refers to an "Emergency call-routing apparatus," which may support an argument that the term implies a distinct physical device.
The Term: "target gateway"
- Context and Importance: Infringement of claim 1 hinges on the existence and identity of this element. Microsoft may argue that its system lacks a "target gateway" that is "coupled to" its resiliency feature in the manner required by the claim.
- Intrinsic Evidence for a Broader Interpretation: The term itself suggests its function is to be the "target" of a routed call. A party could argue that any gateway designated as the destination for calls during a failover event, such as the "local PSTN gateway" alleged in the complaint (Compl. ¶25), meets this definition.
- Intrinsic Evidence for a Narrower Interpretation: The claim requires the "target gateway" to be "coupled to the emergency call router" (’868 Patent, col. 9:26-27). This may be construed to require a specific type of connection beyond merely being a destination for a call. The patent specification consistently uses the term "access gateway" when describing the local network's connection point; the choice of a different term, "target gateway," in the claim may imply a distinct and separate structure.
VI. Other Allegations
- Indirect Infringement: The complaint alleges induced infringement, stating that Microsoft provides and disseminates "product descriptions, operating manuals, and other instructions on how to implement and configure the Accused Products" that instruct users on setting up the infringing functionality (Compl. ¶35). Several URLs to Microsoft's support and documentation websites are provided as examples.
- Willful Infringement: The complaint alleges that Microsoft has had knowledge of the ’868 Patent "since at least the date of service of this Complaint" (Compl. ¶34). This allegation appears to support a claim for post-suit willfulness only, as no facts supporting pre-suit knowledge are alleged.
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope: can the term "emergency call router," which the patent specification arguably presents as a discrete apparatus, be construed to cover the accused "Survivable Branch Appliance," a software-based resiliency feature integrated into a larger server product?
- A key evidentiary question will be one of structural connection: does the accused system contain a "target gateway" that is "coupled to" the accused "emergency call router" as required by claim 1? The case may turn on whether routing a call to a local PSTN gateway is sufficient to prove the two components are "coupled."
- Another central question will be one of technical proof: what evidence will be presented to demonstrate that the accused system performs the claimed step of "determin[ing] whether the call request is for a call of the first selected call-type" and, critically, that this determination occurs "prior to" the routing operation, as the claim language explicitly requires?