Private PoC Messaging via SIP REFER and MESSAGE Routing
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Solution Overview
Problem
In Push to Talk over Cellular (PoC) networks, there is no capability to send private communications to specific participants within a group session, leading to messages being distributed to all participants instead of intended recipients, especially in scenarios where anonymity is involved.
Innovation Solution
A method using SIP REFER messages is implemented, where a PoC client sends a SIP REFER message to a PoC participating Server, which forwards it to a PoC Controlling Server, creating a SIP MESSAGE method addressed to the target participant, allowing private message content to be sent without broadcasting to all participants in the group session.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If messages are distributed to all participants in a PoC group session, then group communication capability is maintained, but privacy of individual communications is lost
Solution Approach 1:
The patent segments the group communication functionality into two distinct modes: group messaging (broadcast to all participants) and private messaging (point-to-point within group). This is achieved by implementing separate message handling paths in the PoC client - one for group messages and another for private messages using SIP MESSAGE method. The segmentation allows simultaneous support for both group communication capability and individual message privacy without compromising either function.
2Loss of information
If anonymous participants are supported in PoC sessions, then user privacy is protected, but ability to send targeted private messages is lost
Solution Approach 1:
The patent introduces the PoC server as an intermediary that manages anonymous participant identities. When a participant joins anonymously, the server assigns a temporary identifier. For private messaging between anonymous participants, the system uses this intermediary to route messages correctly - the SIP MESSAGE method includes the target participant's identifier in the To header, allowing the server to deliver private messages to the correct anonymous participant without requiring them to reveal their real identity. This intermediary mechanism resolves the conflict between anonymity and targeted messaging capability.
3Adaptability or versatility
If standard PoC protocols are used, then interoperability is achieved, but private communication functionality is unavailable
Solution Approach 1:
The patent implements multi-functionality by making the PoC client capable of operating in multiple modes using the same underlying SIP infrastructure. The client can switch between standard PoC group communication mode and private messaging mode (using SIP MESSAGE method) seamlessly. Both functions share common components including SIP stack, session management, and network connectivity, while adding private messaging capability requires minimal additional complexity - primarily the ability to detect and handle SIP MESSAGE methods and route them appropriately. This universal approach enables private communication capability without proportionally increasing overall system complexity.
Data Source
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AI summary
A method of sending a communication to a Participant in a PoC Group Session. A PoC client sends a SIP REFER message to a PoC participating Server, which forwards it to a PoC Controlling Server. The SIP REFER message comprises an identity of a target Participant in the Group Session and a message content. The PoC Controlling Server creates a SIP MESSAGE method, the MESSAGE addressed to the target Participant and including the message content. The SIP MESSAGE is then sent to a target Participating Server that serves the target Participant. In this way, the PoC client can send private message content via the PoC Controlling Server to another Participant in a PoC Group Session without sending it to all Participants.