Untitled case

Unified Patents PTAB Data, acting as a petitioner, initiated an inter partes review (IPR) against US8310990 at the Patent Trial and Appeal Board (PTAB), naming Lemko Corp. as the patent owner. While Unified Patents is generally known as a membership organization that seeks to deter Non-Practicing Entities (NPEs) by challenging patents through IPRs, often on behalf of its members, the specific real parties in interest for this IPR are AT&T Services Inc. and Microsoft Corporation. These operating companies are also involved in parallel patent infringement litigation filed by Lemko Corp. against AT&T Inc. (Case No. 25-cv-00305-JRG) in the Eastern District of Texas, which began on March 17, 2025.

The patent at issue, US8310990, broadly relates to computer networks, multiplex communication, video distribution, and security. More specifically, it describes systems and methods for peer-to-peer, distributed mobile architecture (DMA) networks, with Lemko having demonstrated its DMA technology, including the '990 patent, to AT&T in 2013. The accused products or services are those offered by AT&T and Microsoft that allegedly infringe this patent, likely pertaining to their network communication and distributed architecture technologies as implicated by Lemko's initial infringement suit.

The IPR, IPR2025-01142, was not instituted by the PTAB due to procedural grounds, specifically a discretionary denial. The Patent Owner, Lemko Corp., requested discretionary denial, arguing against institution based on the advanced age of the patent (issued over twelve years prior) and the principle of "settled expectations". This decision highlights a trend at the PTAB where discretionary denials have increased, influenced by factors such as the "settled expectations" doctrine and the ongoing district court litigation, particularly when a district court trial is scheduled to occur before a final written decision in the IPR. The case is notable for demonstrating the PTAB's application of discretionary denial factors, such as "settled expectations," which consider the length of time a patent has been in force, and the linkage between IPR proceedings and parallel district court infringement cases in determining institution.

I'll research the key legal developments in this litigation. Let me start with several parallel searches.

Let me dig into the docket details, the IPR institution decision, and parallel proceedings.

Key Legal Developments & Outcome — Lemko Corp. v. AT&T (E.D. Tex. 2:25-cv-00305-JRG)

Below is a chronological account of the litigation as it has developed through the present posture (last docket update ~2026-04-13). Where a fact is drawn from a secondary aggregator rather than a primary PACER document, I flag it. No trial, verdict, or final disposition has occurred on the merits as of this writing.

Metadata reconciliation note (flagged per instructions): The case metadata lists the petitioner as "Unified Patents PTAB Data." The primary PTAB records for IPR2025-01142 name the Petitioners as Microsoft Corporation and AT&T Services, Inc. (not Unified Patents, LLC). The "Unified Patents" attribution in the metadata appears to be a data-source mislabel — the substantive petitioners are the two operating companies. This is consistent with the earlier section of this case summary, which already identified Microsoft and AT&T as the real parties in interest. I treat Microsoft/AT&T as the true petitioners.

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1. Filing & Initial Pleadings

• 2025-03-17 — Complaint filed. Lemko Corporation (Schaumburg, IL) filed a 35 U.S.C. § 271 patent infringement suit against AT&T in the U.S. District Court for the Eastern District of Texas, Marshall Division, assigned to Judge Rodney Gilstrap (Case No. 2:25-cv-00305-JRG). Source: Lemko press release, 2025-03-17; Docket (aggregated).
• Asserted patents (7): U.S. Patent Nos. 7,840,230; 7,979,066; 8,224,322; 8,310,990; 8,340,667; 8,359,029; 9,198,020. (Comp. ¶¶ 28–34; see also Dkt. 79 n.2). All are related to but distinct from the patents Lemko asserted against Microsoft/Affirmed Networks in the parallel NDTX case.
• Accused products/services: the AT&T Private 5G Edge network platform and the AT&T Private Mobile Connection service. Lemko's infringement theory maps modern 5G core functions (UDM/UDR, AMF/SMF/UPF, IMS) onto the claimed 2G/3G-era architecture elements ("HLR module," "MSC module," "BSC module," etc.), i.e., the case will turn on whether 5G network-function analogs satisfy legacy-architecture claim limitations. (Compl. ¶¶ 83–90; complaint analysis.)
• Named defendants (initial): AT&T Inc.; AT&T Enterprises LLC; AT&T Communications LLC; AT&T Mobility LLC; AT&T Mobility LLC II; AT&T Services, Inc.
• Service (2025-03-19 to 2025-03-25): AT&T Communications LLC served 3/19/2025; AT&T Inc., AT&T Service, Inc., AT&T Mobility LLC served 3/25/2025. (Dkts. 6, 12–14.)
• 2025-03-26 to 2025-03-27 — Lemko's counsel appeared: Paul Andre (lead, Dkt. 8 & Dkt. 11 designation), Lisa Kobialka (Dkt. 9), James Hannah (Dkt. 10), and Aaron M. Frankel (Dkt. 7). All from Kramer Levin Naftalis & Frankel LLP (now Herbert Smith Freehills Kramer); Elizabeth L. DeRieux (Capshaw Derieux LLP) also appears for Lemko.
• 2025-03-31 — Answers extended. Unopposed applications extended all AT&T defendants' answer deadline to 2025-05-26 (Dkts. 15–18). Defense counsel filing the extensions: Deron R. Dacus (The Dacus Firm, PC).
• Answers / counterclaims: The aggregated docket confirms answers were due 2025-05-26, but I did not obtain a primary copy of the answers, and I cannot confirm from the sources retrieved whether AT&T pleaded invalidity and/or non-infringement counterclaims in the answer. This should be verified against PACER (the answer filings would be in the Dkt. 19–30 range). Treat as unconfirmed rather than assume.

2. Party Changes

• 2025-06-11 — Two defendants terminated. Per PacerMonitor's docket summary (accessed 2026), AT&T Inc. and AT&T Communications LLC were terminated as parties on 2025-06-11. The remaining defendants are AT&T Enterprises LLC, AT&T Mobility LLC, AT&T Mobility LLC II, and AT&T Services, Inc. — the caption in Judge Gilstrap's later opinion confirms these four remain. (Dkt. 79, caption.) The termination order/voluntary dismissal document itself was not retrieved; the reason (likely voluntary dismissal of two entities) is not confirmed.

3. Pre-Trial Motions of Substance

Motion to Transfer Venue — DENIED (2026-03-06)

• Defendants' Motion to Transfer to the Northern District of Texas (Dkt. 33) was brought under the first-to-file rule (not § 1404(a) convenience), arguing that this case substantially overlaps with the earlier-filed Lemko Corp. v. Microsoft Corp. et al., No. 3:22-cv-363-K (N.D. Tex.) ("NDTX Case"). (Dkt. 31 at 1.) Lemko opposed (Dkt. 37).
• Ruling — 2026-03-06 — Dkt. 79, Memorandum Opinion and Order (Judge Gilstrap): transfer DENIED. The Court held there was no "substantial overlap" because: (1) different defendants (Microsoft/Affirmed Networks in NDTX vs. the AT&T entities here); (2) different accused technology platforms (Azure Private 5G Core here vs. Affirmed Mobile Core in NDTX); (3) consequently, discovery would not substantially overlap; and (4) none of the seven Asserted Patents in this case are asserted in the NDTX Case. The Court applied Cadle Co. v. Whataburger of Alice, Inc., 174 F.3d 599 (5th Cir. 1999), and Int'l Fidelity Ins. Co., 665 F.3d 671 (5th Cir. 2011). The transfer motion did not raise § 1404(a) convenience or the "settled expectations" doctrine.
• Significance: The case remains in the Marshall Division before Judge Gilstrap, and the NDTX Microsoft litigation was confirmed to be a separate, non-overlapping track as to patents, products, and defendants.

Other motions

• I did not locate a ruling on any motion to dismiss in this EDTX case. (Contrast the parallel NDTX Microsoft case, where motions to dismiss were litigated extensively — see §6 below.) No motion to stay pending IPR was filed by AT&T: the Patent Owner's IPR papers expressly note that "Petitioners have not sought a stay in the District Court Action." (Patent Owner's Request for Discretionary Denial, Fintiv Factor 1.)
• No summary judgment, Markman, or Daubert rulings were found. Whether claim construction has occurred is unconfirmed; the docket update I could reach does not show a Markman order as of early 2026.

4. Claim Construction (Markman)

• No Markman order was located. Given the March 2026 transfer ruling and the fact this case appears to still be in an early/mid pre-trial posture, it does not appear the case has reached a claim-construction ruling. The substantive claim-construction fights on the related-patent family have instead played out at the PTAB (see §5 and §6). Treat "no Markman yet" as a reasonable inference, not a confirmed docket fact.

5. Parallel PTAB Proceedings — The Dominant Development

IPR2025-01142 (the '990 patent) — INSTITUTION DENIED (2025-11-20)

• Petition filed 2025-06-20 by Microsoft Corporation and AT&T Services, Inc., challenging claims 1 and 3–9 of U.S. Patent 8,310,990 on a single ground: anticipation under § 102 by "Flore" (U.S. Pub. 2007/0021120). Petitioner mapped Flore's Inter-AS Anchor to the "first DMA gateway," its SGSN to the "second DMA gateway," and the Gn-interface PDP-context handover to the claimed routing steps. Petitioner emphasized that the '990 patent's parent, U.S. 7,855,988, had already been found anticipated by Flore in a prior FWD. (Ex Parte petition summary; arcticinvent.)
• Patent Owner's Request for Discretionary Denial was filed under the USPTO's "Interim Processes for PTAB Workload Management" and "Interim Director Discretionary Process," advancing:
  • "Settled expectations" — the '990 patent issued over twelve years earlier; AT&T had longstanding knowledge of Lemko's technology (2013 emails, Exs. 2005–2007); and Lemko made substantial product investments.
  • Fintiv factors 1–6 — no stay sought; projected jury trial earlier than the projected FWD date; significant co-pending litigation investment; overlapping issues; same parties; and allegedly non-meritorious challenges.
  • 35 U.S.C. § 325(d) (Advanced Bionics) — the Board had already rejected Microsoft's hardware-vs-computer-readable-medium arguments in the prior '988 proceeding.
• Decision date 2025-11-20: PTAB denied institution — the IPR is not instituted (status "Discretionary Denial"; "Not Instituted – Procedural"). (IPVerse/GreyB case record: Institution Decision Date Nov 20, 2025; status "Discretionary Denial.") The Director's reliance on "settled expectations" plus the parallel-litigation trial timing is the notable doctrinal feature of this case.
• Caveat: I retrieved the status fields and the briefing structure, but not the four corners of the Nov 20, 2025 institution decision itself. The precise weight the Director gave to each Fintiv factor and to settled expectations should be confirmed from the decision document (PTAB Paper 9).

Prior/related PTAB proceedings (the '988-family line)

• IPR2023-00529 — Microsoft/Affirmed Networks v. Lemko, on U.S. 7,653,414 (exhibit list retrieved; outcome not confirmed in the sources retrieved).
• IPR2023-00530 — Microsoft v. Lemko: institution DENIED (Paper 8, 2023-09-25) (Ex. 2001 to the later '990 proceeding).
• IPR2023-00531 — Microsoft/Affirmed Networks v. Lemko, on U.S. 7,855,988 (parent of the '990): Final Written Decision 2024-09-10 finding the challenged claims unpatentable/anticipated by Flore (FWD; oral argument 2024-07/

The IPR, IPR2025-01142, was filed by Unified Patents PTAB Data, with AT&T Services Inc. and Microsoft Corporation identified as the real parties in interest. While Unified Patents is a membership organization that files IPRs to deter patent assertions, it does not act as a law firm for its members. Therefore, the counsel of record would represent the real parties in interest, AT&T Services Inc. and Microsoft Corporation.

Based on the "PETITIONER'S POWER OF ATTORNEY" for IPR2025-01142, the following attorneys represent Microsoft Corporation:

• Scott M. Border (Lead Counsel)

  • Firm: Winston & Strawn LLP
  • Office Location: Washington, D.C.
  • Note: Robert N. Kang, also from Winston & Strawn LLP, was a speaker at the 2025 Corporate IP Strategy Conference, discussing "Litigation - Forum Shopping & Funding Disclosures," suggesting experience in patent litigation strategy.

• Robert N. Kang (Back-Up Counsel)

  • Firm: Winston & Strawn LLP
  • Office Location: San Francisco, CA
  • Note: Robert N. Kang, a partner at Winston & Strawn LLP, was a speaker at Unified Patents' 2025 Corporate IP Strategy Conference, participating in a panel on "Litigation - Forum Shopping & Funding Disclosures," indicating experience in patent litigation matters.

While Unified Patents has its own team of in-house senior patent counsel who prepare and litigate post-grant proceedings before the PTAB, such as Jordan Rossen, David Seastrunk, and Michelle Callaghan, they represent Unified Patents in its capacity as a petitioner, not necessarily the underlying real parties in interest in every IPR.

I'll research counsel of record for the defendants. Let me run several targeted searches.

Counsel of Record — Defendants

Important scope note first. The case identified in the metadata is the PTAB proceeding (IPR2025-01142), which has no "defendants." The corresponding patent infringement case is Lemko Corporation v. AT&T Inc. et al., No. 2:25-cv-00305-JRG (E.D. Tex., Marshall Div., Judge Rodney Gilstrap). The named defendants are AT&T Inc., AT&T Enterprises LLC, AT&T Communications LLC, AT&T Mobility LLC, AT&T Mobility LLC II, and AT&T Services, Inc. (AT&T Communications LLC was terminated 06/11/2025). There is also a separate N.D. Tex. action against Microsoft Corp./Affirmed Networks (discussed at the end). Below I separate verified from unverified entries — please treat the sourcing caveats seriously, because the full docket sheet was not retrievable.

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A. AT&T defendants — E.D. Tex. (2:25-cv-00305-JRG)

What I could NOT verify. I was unable to retrieve the defendants' notices of appearance or the Answer/counterclaims from the docket. The two free docket mirrors I reached were stale or truncated — Justia Dockets shows the docket only through March 31, 2025 ("This docket was last retrieved on March 31, 2025"), and the PACER Monitor party/counsel block for 2:25-cv-00305 was cut off mid-listing (its last update stamp reads 04/13/2026). If O'Melveny is lead counsel, additional O'Melveny attorneys (and possibly in-house AT&T counsel) have almost certainly entered appearances pro hac vice; I could not identify any of them and will not guess. Any list below "lead + local" for AT&T should be treated as incomplete.

One frequent confusion to avoid: Kristopher Kastens (Herbert Smith Freehills) appears on Law360's Lemko v. AT&T case page, but he is with plaintiff Lemko's firm (Kramer Levin merged into Herbert Smith Freehills Kramer) — he is not defense counsel. Likewise Elizabeth L. DeRieux (Capshaw Derieux LLP) is plaintiff-side local counsel. Confirmed plaintiff-side appearances on the docket: Paul Andre (attorney in charge), Lisa Kobialka, James Hannah, Aaron M. Frankel, and Elizabeth L. DeRieux — docket entries 7–11 (3/26–3/27/2025).

Sources: Justia docket/opinion for 2:25-cv-00305 (Dkt. 79, Memorandum Opinion & Order denying Dkt. 33 Motion to Transfer Venue, signed 3/6/2026) — https://law.justia.com/cases/federal/district-courts/texas/txedce/2:2025cv00305/[236690](/patent/236690)/79/ ; Justia Dockets (Dkts. 6–18) — https://dockets.justia.com/docket/texas/txedce/2:2025cv00305/236690 ; PACER Monitor (party/counsel block) — https://www.pacermonitor.com/public/case/57258476/Lemko_Corporation_v_ATT_Inc_et_al ; Law360 attorney page for Jeffery D. Baxter — https://www.law360.com/firms/o-melveny-myers/attorneys/jeffery-d-baxter ; O'Melveny bio — https://www.omm.com/professionals/jeff-baxter/ ; Lemko press release naming plaintiff's counsel — https://www.lemkocorp.com/lemko-corporation-files-patent-infringement-lawsuit-against-att/

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B. Microsoft / Affirmed Networks — N.D. Tex. (Lemko Corp. v. Microsoft Corp. et al., No. 3:22-cv-00363-L-BT)

I found no verified district-court counsel identification for Microsoft or Affirmed Networks. Reporting confirms only that Affirmed Networks filed successive motions to dismiss (May 2022; a second round after the September 2023 partial grant with leave to amend; a third fully briefed) — see RPX/Mondaq coverage at https://litigation.rpxcorp.com/news/85618-at-t-hit-in-lemko-s-edge-computing-campaign — but those sources do not name defense counsel. Firm names for Microsoft here would be speculation; I am not supplying any.

For the PTAB side, the previously generated section of this case summary identifies Scott M. Border (lead) and Robert N. Kang (back-up), Winston & Strawn LLP, as counsel for Microsoft in IPR2025-01142 pursuant to the petitioner's power of attorney. I did not independently re-verify that in this pass; treat it as IPR-only counsel and separately confirm before citing.

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C. Flagged contradiction with the case metadata

The metadata and the existing case summary describe the petitioner in IPR2025-01142 as "Unified Patents PTAB Data" (a Unified Patents entity). The PTAB documents I retrieved, however, caption the proceeding as:

MICROSOFT CORPORATION and AT&T SERVICES, INC., Petitioners, v. LEMKO CORPORATION, Patent Owner — Case IPR2025-01142, U.S. Patent No. 8,310,990

(See Patent Owner's Request for Discretionary Denial and Patent Owner's Power of Attorney, https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1558047](/patent/1558047)/download-documents). I found no document naming any Unified Patents entity as petitioner in this IPR. The likeliest explanation is that "Unified Patents PTAB Data" is a data-source/party-label artifact in the case metadata rather than the real petitioner of record — but per the operating rules I am flagging the discrepancy rather than resolving it.

Two related, useful data points from those same PTAB filings: (1) Lemko's PTAB counsel of record is Herbert Smith Freehills Kramer (US) LLP — lead James Hannah (Redwood Shores, CA; USPTO Reg. No. 56,369), with Aaron M. Frankel, Jeffrey H. Price, Jenna Fuller, and Jeffrey Eng (New York) as back-up counsel, under USPTO Customer No. 31013; (2) Lemko's discretionary-denial request relies on the co-pending E.D. Tex. action (it cites Dkt. 1 and Dkt. 46 in 2:25-cv-00305), which is why the district-court and IPR tracks are effectively the same dispute.

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D. Bottom line

• Verified: Deron R. Dacus (The Dacus Firm, Tyler, TX) is defendants' E.D. Tex. local counsel of record for the AT&T entities.
• Probable but not docket-confirmed: Jeff Baxter (O'Melveny & Myers, Dallas) as AT&T's lead counsel in Lemko v. AT&T.
• Not determined: any additional O'Melveny pro hac vice counsel, any AT&T in-house counsel of record, and all Microsoft/Affirmed Networks district-court counsel. These require a PACER pull of the full docket sheets (E.D. Tex. 2:25-cv-00305 and N.D. Tex. 3:22-cv-00363) — the free mirrors available to me were stale and truncated.