This page is the campaign hub for patent suits by Session Link Research LLC, which its complaints describe as a Texas limited liability company with its principal place of business in Marshall, Texas. All four suits were filed on November 3, 2026, in the Marshall Division of the Eastern District of Texas, and all four assert U.S. Patent 9,392,436.
The seven patents
The patents are U.S. Patent 9,961,209, "Codec Selection Optimization," issued May 1, 2018; U.S. Patent 9,392,436, "Method and Apparatus for Voice Over LTE," issued July 12, 2016; U.S. Patent 8,265,062, "System and Method for Accomplishing Special Call Treatment in a Voice Over Internet Protocol Telephone System," issued September 11, 2012; U.S. Patent 9,083,771, "System and Methods for Multi-Participant Teleconferencing Using Preferred Forms of Telecommunication," issued July 14, 2015; U.S. Patent 10,057,429, "Pre-Paid Voice Calling Using Sponsored Data Roaming," issued August 21, 2018; U.S. Patent 11,284,459, "Data Access Security," issued March 22, 2022; and U.S. Patent 10,979,462, "Identifying Voice Over LTE Users," issued April 13, 2021. The USPTO copies of the patents list those titles and issue dates, and each of the seven lists the same company as its assignee. Each complaint says Session Link is the sole and exclusive owner of the patents it asserts.
The AT&T and T-Mobile complaints say the named inventors developed the technology of the '209, '436, '062, and '771 patents at that company. The Verizon complaint says the same of all seven patents, and the Ribbon complaint says it of the '436 patent.
Which suit asserts which patents
Each complaint pleads one count for each patent it asserts and names an exemplary claim in each count. The three carrier complaints name the same exemplary claims, and the Ribbon complaint names claim 1 of the '436 patent. Patents appear by their last three digits; the full numbers are above.
| Patent | Exemplary claim | AT&T, No. 2:26-cv-00992 | T-Mobile, No. 2:26-cv-00994 | Verizon, No. 2:26-cv-00995 | Ribbon, No. 2:26-cv-00996 |
|---|---|---|---|---|---|
| '209 | Claim 1 | Asserted | Asserted | Asserted | Not asserted |
| '436 | Claim 1 | Asserted | Asserted | Asserted | Asserted |
| '062 | Claim 1 | Asserted | Asserted | Asserted | Not asserted |
| '771 | Claim 11 | Asserted | Asserted | Asserted | Not asserted |
| '429 | Claim 15 | Asserted | Asserted | Asserted | Not asserted |
| '459 | Claim 24 | Asserted | Asserted | Asserted | Not asserted |
| '462 | Claim 1 | Asserted | Asserted | Asserted | Not asserted |
The suits against the carriers
Session Link Research LLC v. AT&T Mobility LLC, No. 2:26-cv-00992, against AT&T Mobility LLC, AT&T Services, Inc., and AT&T Enterprises LLC, accuses AT&T's 5G and 5G+ network, including the AT&T 5G Standalone Core, data centers, base stations, and associated equipment, services, and platforms such as AT&T PREPAID. Session Link Research LLC v. T-Mobile USA, Inc., No. 2:26-cv-00994, against T-Mobile USA, Inc. and T-Mobile US, Inc., accuses T-Mobile's 5G network, including Ultra Capacity 5G and Extended Range 5G, the 5G Standalone Core, data centers, base stations, and associated equipment, services such as T-Mobile Connect, and platforms. Session Link Research LLC v. Verizon Communications, Inc., No. 2:26-cv-00995, against Verizon Communications, Inc. and Cellco Partnership d/b/a Verizon Wireless, accuses Verizon's 5G Ultra Wideband network, including the standalone 5G core, data centers, base stations, and associated equipment, services, and platforms such as Verizon Connect and ThingSpace.
Each of the three complaints alleges, on information and belief, that the carrier's networks are designed and operated in compliance with 3GPP, GSMA, and IETF standards, including those governing VoLTE, VoNR, SIP and SDP signaling, codec negotiation, inter-operator connectivity, and roaming, and each count maps its exemplary claim to the carrier's network by reference to those standards. Each count alleges direct, induced, and contributory infringement, pleads knowledge at least as of the date of the complaint, and alleges in the alternative, on information and belief, that the defendants were willfully blind through a policy of not reviewing the patents of others. These are Session Link's allegations.
The Ribbon suit
Session Link Research LLC v. Ribbon Communications Inc., No. 2:26-cv-00996, pleads one count, on the '436 patent. The complaint describes Ribbon, on information and belief, as a Delaware corporation with its principal place of business in Plano, Texas. It accuses Ribbon Session Border Controllers, Policy and Routing Servers, and IMS Core / Cloud-Native IMS products, with associated hardware and software, and maps claim 1 to the Ribbon session border controller acting as an interconnection border control function, relying on 3GPP TS 24.229. The count alleges direct, induced, and contributory infringement.
Each of the four complaints asks for a permanent injunction and damages no less than a reasonable royalty, and each demands a jury.
The proceedings
The table lists each suit by number, with the status its docket shows through November 6, 2026.
| No. | Filed | Defendants | Patents | Status on the docket |
|---|---|---|---|---|
| 2:26-cv-00992 | November 3, 2026 | AT&T Mobility LLC, AT&T Services, Inc., and AT&T Enterprises LLC | '209, '436, '062, '771, '429, '459, '462 | Assigned to District Judge Rodney Gilstrap and Magistrate Judge Roy S. Payne. Summons issued to all three defendants November 3, 2026. |
| 2:26-cv-00994 | November 3, 2026 | T-Mobile USA, Inc. and T-Mobile US, Inc. | '209, '436, '062, '771, '429, '459, '462 | Complaint, disclosure statement, and patent and trademark form filed November 3, 2026; summons issued November 4, 2026. |
| 2:26-cv-00995 | November 3, 2026 | Verizon Communications, Inc. and Cellco Partnership d/b/a Verizon Wireless | '209, '436, '062, '771, '429, '459, '462 | Assigned to District Judge Rodney Gilstrap and Magistrate Judge Roy S. Payne. Summons issued to both defendants November 4, 2026. |
| 2:26-cv-00996 | November 3, 2026 | Ribbon Communications Inc. | '436 | Assigned to District Judge Rodney Gilstrap and Magistrate Judge Roy S. Payne. Summons issued to Ribbon November 4, 2026. |
What to watch next
Watch for service on the defendants in all four suits and their answers or Rule 12 motions, including any motion addressing venue, and for any motion to consolidate the cases. Any of these cases can end at any time, including by settlement or voluntary dismissal.