Prior art

Analysis of Prior Art for US Patent 11,991,600

As of May 13, 2026, a detailed review of the prosecution history and the face of US Patent 11,991,600 has been conducted to identify the prior art of record. The following analysis details the references cited by the examiner during prosecution and their potential relevance to the patent's claims. This information is critical for understanding the patent's scope and the arguments being made in the ongoing litigation (Case 1:24-cv-01199 and IPR2026-00105).

The core invention of US 11,991,600 is the automatic selection of a message bearer (SMS, cellular data, or WLAN) by a single messaging client on a sending device, based on a response from a server after checking the recipient's phone number. The server and the specialized "Packet Switched Message Service" (PSMS) are central to this process.

Based on the patent's file wrapper and listed citations, the following references were considered by the USPTO.

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Key Prior Art Cited During Prosecution

The following patents were cited by the USPTO examiner and are listed on the face of the issued US Patent 11,991,600. These references were overcome during prosecution but are highly relevant to the ongoing validity challenges.

1. US Patent No. 7,792,533 B2 (to Ahya et al.)

• Full Citation: US Patent 7,792,533 B2, "Method and system for intelligently routing short messages"
• Filing Date: June 13, 2005
• Publication Date: September 7, 2010
• Assignee: AT&T Mobility II LLC
• Brief Description: Ahya describes a system for routing short messages. It involves an "Intelligent Routing Hub" that receives a message, determines the recipient's network, and selects the most efficient path for delivery. This system can choose between different bearers, such as SMS or MMS, based on network conditions and message content, to ensure reliable and cost-effective delivery. It teaches routing messages based on network intelligence rather than just the recipient's address.
• Potential Anticipation of Claims: Ahya appears relevant to the general concept of intelligent message routing. It potentially anticipates the broader ideas within Claim 1 and Claim 13 concerning the automatic selection of a bearer. Specifically, it discloses a centralized hub (similar to the claimed "server") making a decision on how to route a message. However, the claims of US 11,991,600 are distinguished by specifying a client-side action based on a server response and the use of a particular type of non-SMS/MMS "PSMS" over both cellular and WLAN connections.

2. US Patent No. 8,213,923 B2 (to Ejzak)

• Full Citation: US Patent 8,213,923 B2, "System and method for selecting a bearer for a communication session"
• Filing Date: November 29, 2007
• Publication Date: July 3, 2012
• Assignee: Motorola, Inc.
• Brief Description: Ejzak discloses a method for a mobile device to select the optimal bearer for a communication session (e.g., voice, data, messaging). The device considers factors like available networks (e.g., cellular, Wi-Fi), Quality of Service (QoS) requirements, user preferences, and cost. It describes a process where the device actively assesses available bearers and makes an automated selection before initiating a session.
• Potential Anticipation of Claims: This reference is highly relevant to the core concept of automatic bearer selection performed by the sending device. It speaks directly to the steps of selecting between different bearers like cellular and WLAN, as recited in Claims 1, 13, 21, and 29. The novelty of US 11,991,600 in light of Ejzak likely resides in the specific mechanism of sending the recipient's phone number to a remote server for a status check and receiving a response that dictates the selection, all within the context of a unified messaging client for a non-standard PSMS. Ejzak's focus is more on the device's independent assessment of network conditions rather than a server-directed choice based on recipient status.

3. US Patent Application Publication No. 2007/0037576 A1 (to Aborn)

• Full Citation: US 2007/0037576 A1, "Method and apparatus for routing messages between wireless devices"
• Filing Date: August 11, 2005
• Publication Date: February 15, 2007
• Assignee: Cingular Wireless II, LLC
• Brief Description: Aborn describes a messaging system where a sender's device can send a message that is routed through various networks. A "Message Router" determines if the recipient is available on an IP-based network (like one accessible via Wi-Fi or GPRS) before defaulting to a standard network like SMS. The system checks the "presence" or online status of the recipient on an IP network to decide the delivery method.
• Potential Anticipation of Claims: Aborn is very relevant as it discloses checking a recipient's status on an IP network to decide whether to send a message via an IP-based bearer or fallback to SMS. This strongly aligns with the process described in Claims 1, 21, and 29. The key distinguishing feature in US 11,991,600 appears to be the definition of its specific "PSMS" (distinct from SMS/EMS/MMS) and the performance of these steps across three different bearer types (SMS, cellular packet-switched, and WLAN packet-switched) by the same messaging client based on the server's response. Aborn's disclosure of checking presence and then selecting a bearer could be argued to anticipate the foundational steps of these claims.

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This analysis is based on the publicly available record for US Patent 11,991,600 and is for informational purposes only. It is not a legal opinion on the validity of the patent. The final determination of validity will be made by the PTAB and/or the District Court.