Missed Call LLC v. Zendesk Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Missed Call, LLC (Texas)
  • Defendant: Zendesk, Inc. (Delaware)
  • Plaintiff’s Counsel: Ramey LLP
• Case Identification: 7:25-cv-00558, W.D. Tex., 12/08/2025
• Venue Allegations: Plaintiff alleges venue is proper because Defendant has a regular and established place of business in the district and has committed acts of infringement there.
• Core Dispute: Plaintiff alleges that Defendant’s customer service and communication systems infringe a patent related to methods for providing users with information about the specific cause of a missed telephone call.
• Technical Context: The technology at issue involves analyzing telecommunication network signals to determine whether a missed call was terminated by the caller or by a network timeout, and then presenting a corresponding notification to the user.
• Key Procedural History: Plaintiff, a non-practicing entity, notes that it and its predecessors have entered into settlement licenses with other entities in prior litigation, but states that none of those licenses involved the production of a patented article.

Case Timeline

Date	Event
2010-07-21	’872 Patent Priority Date
2016-12-27	’872 Patent Issue Date
2025-12-08	Complaint Filing Date

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

U.S. Patent No. 9,531,872 - “Communication Apparatus For Providing An Indication About A Missed Call, And Method Thereof,”

• Patent Identification: U.S. Patent No. 9,531,872, “Communication Apparatus For Providing An Indication About A Missed Call, And Method Thereof,” issued December 27, 2016.

The Invention Explained

• Problem Addressed: Prior art communication devices would indicate that a call was missed but provided no context as to why the call was terminated (Compl. ¶9; ’872 Patent, col. 2:13-18). A user could not distinguish between a call where the caller quickly hung up (potentially less urgent) and a call that rang for a long time before being disconnected by the network (potentially more urgent) (’872 Patent, col. 1:41-49).
• The Patented Solution: The invention describes a communication apparatus (e.g., a mobile phone) that analyzes network signals associated with a missed call. Specifically, it uses a "processing means" to extract a "cause value" from a "cause information element" sent by the telecommunications network upon call termination (’872 Patent, col. 4:10-17). This cause value explicitly indicates whether the disconnection was initiated by the calling user (e.g., a "NORMAL CLEARING" value) or by the network (e.g., a "RECOVERY ON TIME EXPIRY" value), allowing the device to output a corresponding indication of urgency to the user (’872 Patent, Abstract; Fig. 2).
• Technical Importance: The technology aimed to add a layer of contextual intelligence to missed call notifications, enabling users to better prioritize which calls to return based on the likely intent or persistence of the caller (’872 Patent, col. 1:46-49).

Key Claims at a Glance

• The complaint asserts infringement of claims 1-13 (Compl. ¶10). Independent claim 1 is central to the apparatus claims.
• Claim 1 Elements:
  • A communication apparatus for providing an indication about a missed telephone call, comprising:
  • receiving means for receiving an incoming call;
  • a control unit configured to process said received incoming call;
  • output means for outputting information to a user; and
  • processing means for extracting a cause value contained in a cause information element sent from a network;
  • wherein the processing means outputs an indication based on whether the cause value indicates the call was cleared by the caller versus cleared by the network, with the latter being designated as urgent.
• The complaint does not explicitly reserve the right to assert other dependent claims but alleges infringement of the full range of claims 1-13 (Compl. ¶10).

III. The Accused Instrumentality

Product Identification

• The complaint does not name specific Zendesk products or services (Compl. ¶10). It generally accuses "systems, products, and services that facilitate providing of an indication of a missed telephone call" operated by Zendesk (Compl. ¶10).

Functionality and Market Context

• The complaint does not describe the specific functionality of the accused instrumentalities. It alleges in general terms that Zendesk "maintains, operates, and administers" systems that provide an indication of a missed call (Compl. ¶10). No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint states that support for its infringement allegations is contained in an "exemplary table included as Exhibit A" (Compl. ¶11). However, Exhibit A was not filed with the complaint. The narrative allegations state only that Defendant’s systems "facilitate providing of an indication of a missed telephone call that infringe one or more of claims 1-13 of the '872 patent" (Compl. ¶10). The complaint does not provide sufficient detail to construct a claim chart summarizing the infringement theory for any specific claim.

• Identified Points of Contention:
  • Evidentiary Question: The central issue will be whether Plaintiff can produce evidence that Zendesk's systems perform the specific steps recited in the claims. A key question is whether Zendesk's systems, which likely operate on Voice over IP (VoIP) or other application-layer protocols, receive and process a "cause information element" sent from a network in the manner described by the patent, which is grounded in standards like ISDN and UMTS (’872 Patent, col. 3:58-64).
  • Scope Question: A dispute may arise over whether the term "network," as used in the patent, can be construed to cover the cloud-based infrastructure and internet protocols used by modern customer service platforms like Zendesk, as opposed to the traditional telecommunication networks contemplated in the specification.

V. Key Claim Terms for Construction

• The Term: "cause value contained in a cause information element"
• Context and Importance: This composite term is the technical core of the asserted independent claims. The infringement analysis will depend entirely on whether the accused Zendesk systems can be shown to "extract" such a value from such an "element." Practitioners may focus on this term because the patent appears to tie it to specific standardized telecommunication protocols, raising questions about its applicability to different technologies.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claims themselves do not limit the terms to a specific protocol, referring more generally to a "cause value" sent from a "network" (’872 Patent, col. 6:38-44). A party might argue this language should be read to cover any data packet or signal that serves the same function, regardless of the underlying protocol.
  • Evidence for a Narrower Interpretation: The specification explicitly grounds these concepts in established standards, such as "ITU-T recommendation Q.931 regarding the Integrated Services Digital Network (ISDN) or in the 3GPP TS 24.008" (’872 Patent, col. 3:58-64). It also provides specific examples of cause values, such as "RECOVERY ON TIME EXPIRY" and "NORMAL CLEARING," which are defined within those standards (’872 Patent, col. 4:21-22, col. 4:46-47). A party may argue that these specific disclosures limit the claim scope to systems that use these or closely analogous standardized codes.

VI. Other Allegations

• Indirect Infringement: The complaint alleges inducement by asserting that Zendesk "actively encouraged or instructed others (e.g., its customers)" on how to use its systems in an infringing manner (Compl. ¶12). It also pleads contributory infringement, alleging there are "no substantial noninfringing uses for Defendant's products and services" (Compl. ¶13).
• Willful Infringement: Willfulness is predicated on Defendant’s alleged knowledge of the ’872 Patent from "at least the filing date of the lawsuit" (Compl. ¶12, fn. 2). The complaint reserves the right to amend if pre-suit knowledge is discovered, suggesting an initial focus on potential post-filing willfulness (Compl. ¶12, fn. 2; ¶13, fn. 3).

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

The resolution of this case will likely depend on the answers to two primary questions:

1. A core issue will be one of technical equivalence: Can the patent’s claim limitations, which are described in the context of specific telecommunication network standards (e.g., ISDN, UMTS), be construed to read on the functionality of modern, likely cloud-based, VoIP systems such as those operated by Zendesk? The case may turn on whether a signal in Zendesk's system is legally equivalent to the claimed "cause information element."
2. A key evidentiary question will be one of factual proof: As the complaint lacks specific factual allegations mapping product features to claim elements, a central challenge for the Plaintiff will be to discover and present evidence demonstrating that the accused Zendesk systems actually perform the claimed method of extracting a specific "cause value" to distinguish between different types of missed calls.