US 11991600

Patent Summary: US 11,991,600 B2

Date of Analysis: May 13, 2026

A review of US Patent 11,991,600 reveals it pertains to methods for a mobile device to automatically select the best network path for sending a message. The patent is currently the subject of litigation.

Title: Methods for bearer selection performed by a sending mobile device

Assignee: The current assignee is listed as Rembrandt Messaging Technologies LP. However, court documents from related litigation indicate the current owner is HBCU Messaging US LP.

Inventors: Graham Merrett

Filing Date: May 4, 2023

Issue Date: May 21, 2024

Abstract:
The patent describes a method for a sending mobile phone, capable of sending both SMS and packet-switched messages, to select a communication channel (bearer). The method involves retrieving the destination address, sending information representing the receiving phone's number, receiving a response, and then, based on that response, automatically selecting a bearer. The available bearers include an SMS bearer, a packet-switched bearer over a cellular connection, and a packet-switched bearer over a Wireless Local Area Network (WLAN) connection.

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Overview of Independent Claims

The patent includes three independent claims (1, 13, 21, and 29), which define the core scope of the invention. In plain language, they cover the following:

Independent Claim 1: This claim describes a method performed by a sending mobile phone. The core of the method is a multi-step process that is repeated for different messages and recipients.

1. The phone pulls the recipient's phone number from a message.
2. It sends out this phone number information (to a server, for example).
3. It receives a response.
4. Based on the response, it automatically chooses one of three ways to send the message: standard SMS, a data message over a cellular network (like 4G/5G), or a data message over a Wi-Fi (WLAN) connection.
5. After selecting the path, it formats and sends the message.
   Crucially, this entire process is performed by the same messaging application (client) on the phone for sending via any of the three paths, utilizing a specific "packet switched message service" (PSMS) that is distinct from standard SMS, EMS, and MMS.

Independent Claim 13: This claim describes the overall system that enables the method in Claim 1. It includes:

1. A sending mobile phone with a messaging client that retrieves the destination phone number.
2. A server for a "packet switched message service" (PSMS) that receives the phone number from the sending device.
   The server sends a response back to the phone, which then uses this response to automatically select the sending method (SMS, cellular data, or WLAN data), formats the message accordingly, and transmits it. The claim specifies that for messages sent over a WLAN connection, the server receives the message content and forwards it to the recipient.

Independent Claim 21: This claim outlines a more detailed sequence of events for sending three separate messages from a mobile device.

1. First Message (SMS): The device sends a recipient's phone number to a server, gets a response, and based on that, automatically selects and sends the message via SMS.
2. Second Message (Cellular Data): The device sends a second recipient's address to the server, gets a response, and automatically selects and sends the message using a packet-switched bearer over a cellular connection.
3. Third Message (WLAN): The device sends a third destination address (which can represent multiple recipients) to the server. It receives a response indicating that the multiple devices are users of the special packet-switched message service (PSMS), and then automatically selects and sends the message over a Wi-Fi (WLAN) connection.

Independent Claim 29: This claim is similar to Claim 21 but focuses on a scenario where the system defaults to SMS when the advanced messaging service is not available for a recipient.

1. First Message (SMS): Sent via SMS after a server check confirms this is the appropriate bearer.
2. Second Message (Default to SMS): The device sends a destination address to the server. The response explicitly indicates that the message should not be sent via the packet-switched message service (PSMS) to at least one of the intended recipients. Consequently, the device automatically selects SMS for sending the message.
3. Third Message (WLAN): The device sends a third address to the server, receives a response confirming the recipients are associated with the PSMS, and then automatically selects and sends the message over a Wi-Fi (WLAN) connection.

Litigation Status

US Patent 11,991,600 is currently involved in legal proceedings.

• District Court: A patent infringement lawsuit is active in the U.S. District Court for the Western District of Texas (Case 1:24-cv-01199), where HBCU Messaging US LP has sued Apple, Inc.
• Patent Trial and Appeal Board (PTAB): Apple, Inc. has challenged the validity of this patent by filing a petition for Inter Partes Review (IPR), docketed as case IPR2026-00105. This proceeding is pending.