Data Fence LLC v. Youmail Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Data Fence LLC (New Mexico)
  • Defendant: YouMail, Inc. (Delaware)
  • Plaintiff’s Counsel: Silverman, McDonald & Friedman; Rabicoff Law LLC
• Case Identification: 1:25-cv-01504, D. Del., 12/12/2025
• Venue Allegations: Plaintiff alleges venue is proper in the District of Delaware because Defendant is incorporated in Delaware and has committed acts of patent infringement in the district.
• Core Dispute: Plaintiff alleges that Defendant’s unspecified products infringe a patent related to methods and systems for controlling inbound telephone calls.
• Technical Context: The technology addresses the problem of unwanted "spam" or "robocalls" by using a system to evaluate incoming calls and perform actions based on whether the caller has negative characteristics.
• Key Procedural History: The complaint does not mention any prior litigation, licensing history, or post-grant proceedings related to the patent-in-suit.

Case Timeline

Date	Event
2012-10-17	’797 Patent Priority Date
2017-11-14	’797 Patent Issue Date
2025-12-12	Complaint Filing Date

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

U.S. Patent No. 9,819,797 - Methods and systems for inbound call control

Issued November 14, 2017 (’797 Patent). (Compl. ¶8).

The Invention Explained

• Problem Addressed: The patent background describes the "unwelcome intrusion into privacy" caused by the dramatic increase in unsolicited "telemarketing" or "spam" calls, particularly computer-dialed "robocalls." (’797 Patent, col. 1:24-41).
• The Patented Solution: The invention is a call control system that intercepts an incoming call before it reaches the user's telephone. (’797 Patent, col. 5:3-16). The system queries a server to determine if "additional information" exists about the caller, such as a spam score or inclusion on a blacklist. (’797 Patent, col. 5:46-56). If this information indicates a "negative characteristic," the system can perform an operation such as blocking the call or, in a key embodiment, providing an "inquiry" to the caller (e.g., a CAPTCHA-like challenge) to differentiate a human from a robocaller before deciding whether to route the call to the telephone. (’797 Patent, col. 12:5-46; Fig. 13).
• Technical Importance: This approach sought to create an intelligent, automated gatekeeper for landline and VoIP phone systems, moving beyond simple number-based blocking to a dynamic, data-driven evaluation of incoming calls. (’797 Patent, col. 1:63-67).

Key Claims at a Glance

• The complaint asserts infringement of "one or more claims of the ’797 Patent" without identifying specific claims. (Compl. ¶11). Claim 1 is the first independent claim.
• Essential Elements of Independent Claim 1:
  • Receiving an indication of an incoming call directed to a telephone from a caller at a call control unit.
  • The call control unit is positioned between the telecommunication service provider and the telephone.
  • The call is associated with the caller and a telephone number for the caller.
  • Querying, by the call control unit, a server to determine whether additional information associated with the telephone number and the caller exists.
  • If additional information exists, determining whether it indicates that a negative characteristic is associated with the caller or the telephone number.
  • If a negative characteristic is indicated, providing an inquiry to the caller.
  • Upon receipt of a correct response to the inquiry, routing the call to the telephone.
  • Otherwise, blocking the call.
• The complaint does not explicitly reserve the right to assert dependent claims.

III. The Accused Instrumentality

Product Identification

The complaint does not name specific accused products, referring only to the "Exemplary Defendant Products." (Compl. ¶11).

Functionality and Market Context

The complaint alleges that the "Exemplary Defendant Products" practice the technology claimed by the ’797 Patent but provides no specific details about their functionality or operation. (Compl. ¶16). The complaint alleges these products have been made, used, sold, offered for sale, and imported by Defendant. (Compl. ¶11). The complaint does not provide sufficient detail for analysis of the products' technical functionality or market context.

IV. Analysis of Infringement Allegations

The complaint alleges that infringement is detailed in claim charts provided in an "Exhibit 2." (Compl. ¶¶16-17). However, Exhibit 2 was not filed with the complaint. The infringement theory must therefore be inferred from the complaint’s narrative allegations.

The core allegation is that the "Exemplary Defendant Products practice the technology claimed by the ’797 Patent" and "satisfy all elements of the Exemplary '797 Patent Claims." (Compl. ¶16). The complaint alleges direct infringement by Defendant's making, using, and selling of these products, as well as by its employees' internal testing and use. (Compl. ¶¶11-12). Without the claim charts, the specific mapping of product features to claim limitations cannot be analyzed.

No probative visual evidence provided in complaint.

Identified Points of Contention

• Evidentiary Questions: A primary question will be whether Plaintiff can produce evidence demonstrating that the accused products perform each step of the asserted claims. Specifically, what evidence shows that the products, upon identifying a "negative characteristic," proceed to "provid[e] an inquiry to the caller" and then route or block the call based on the response, as required by Claim 1?
• Scope Questions: The analysis may raise the question of whether the functionality of the accused products, once revealed, aligns with the specific sequence of operations recited in the claim (query server -> find negative characteristic -> provide inquiry -> route/block based on response). A deviation from this sequence could be a point of non-infringement dispute.

V. Key Claim Terms for Construction

The Term: "negative characteristic"

Context and Importance

This term is central to the claim's logic, as it is the trigger for providing an "inquiry" to the caller. The scope of this term will determine what types of caller information (e.g., a high spam score, inclusion on a community blacklist, an unverified number) can satisfy this limitation.

Intrinsic Evidence for Interpretation

• Evidence for a Broader Interpretation: The claim itself does not define the term, suggesting it should be given its plain and ordinary meaning. The specification provides a non-exhaustive list of factors used to calculate a "spam score," including report velocity, user credibility, and inclusion on public blocklists, which could all be considered negative characteristics. (’797 Patent, col. 4:58-col. 5:14).
• Evidence for a Narrower Interpretation: The patent repeatedly links the invention to combatting "unsolicited and unwanted telephone calls, so-called ‘telemarketing’ or ‘spam’ calls." (’797 Patent, col. 1:24-26). A defendant may argue that "negative characteristic" should be limited to indicia directly related to such unwanted commercial or fraudulent activity, and not to other types of information.

The Term: "providing an inquiry to the caller"

Context and Importance

This is the key active step performed by the invention after a negative characteristic is found. Whether the accused products perform an action that meets the definition of an "inquiry" will be a critical infringement question.

Intrinsic Evidence for Interpretation

• Evidence for a Broader Interpretation: The specification suggests the inquiry can be simple, such as asking "say your name" or "what state do you live in." (’797 Patent, col. 12:22-24). This could support a reading that covers a wide range of automated prompts or challenges.
• Evidence for a Narrower Interpretation: The specification explicitly links this step to a "challenge-response authentication protocol such as Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA)." (’797 Patent, col. 12:28-32). This could support an argument that the "inquiry" must be a formal test designed to distinguish a human from a machine, not just any automated question.

VI. Other Allegations

Indirect Infringement

The complaint alleges induced infringement, stating that Defendant sells its products to customers and distributes "product literature and website materials" that instruct end users on how to use the products in a manner that infringes the ’797 Patent. (Compl. ¶¶14-15).

Willful Infringement

The complaint does not allege pre-suit knowledge. It asserts that the filing of the complaint and its attached (but not provided) claim charts provides Defendant with "actual knowledge of infringement." (Compl. ¶13). The willfulness allegation appears to be based on alleged post-filing conduct. (Compl. ¶14).

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

1. An Evidentiary Question of Functionality: Given the absence of detailed infringement allegations in the complaint, a central issue will be whether discovery reveals evidence that the accused products perform the specific, multi-step method of Claim 1. The case may turn on whether the accused products actually implement the "inquiry" step as a response to detecting a "negative characteristic."

2. A Definitional Question of Scope: The dispute will likely focus on claim construction, particularly the meaning of "negative characteristic" and "providing an inquiry to the caller." Whether the accused system's criteria for flagging calls and its subsequent actions fall within the patent's definition of these terms will be a key battleground.

3. A Question of Induced Infringement: Can Plaintiff show that Defendant's product literature and user instructions specifically encouraged users to configure and operate the accused products in a way that directly maps to all elements of an asserted claim, thereby demonstrating the requisite intent for inducement?