SIP Answer Message Location Conveyance in Third Party Calls
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Solution Overview
Problem
Current technologies do not effectively convey accurate location information from a first communication device to a second device during a Third Party Call Control scenario, where the location information is only provided in SIP request messages and not in SIP responses, leading to issues in emergency calls initiated via CTI applications.
Innovation Solution
The method involves sending a first invite message from a server triggered by a third communication device to the first communication device, with the first communication device responding with an answer message that includes its location information, which is then inserted into a second invite message sent to the second communication device, allowing accurate location information to be conveyed via the server.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If location information is only provided in SIP request messages and not in SIP responses, then the protocol structure remains simple and standardized, but accurate location information cannot be conveyed during Third Party Call Control scenarios
Solution Approach 1:
The patent inverts the conventional approach by placing location information in the SIP response message (200 OK) instead of only in request messages. This allows the first communication device to convey its location information to the server through the answer message, which is then forwarded to the second communication device, resolving the contradiction between maintaining protocol simplicity and ensuring location accuracy.
Solution Approach 2:
The server acts as an intermediary that receives the answer message containing location information from the first communication device, extracts this information, and inserts it into the second invite message sent to the second communication device. This mediator approach enables location information conveyance without requiring direct modification of the standard SIP protocol structure.
2Reliability
If additional messages are sent to convey location information, then accurate location data can be provided, but the message exchange becomes more complex and time-consuming
Solution Approach 1:
The patent merges the location information conveyance function with the existing answer message (200 OK) that is already part of the SIP call setup procedure. By combining these two functions into a single message exchange, the system achieves accurate location information transmission without requiring additional messages, thus maintaining call setup efficiency.
Solution Approach 2:
The location information is included in the answer message before the second invite message is sent to the second communication device. This preliminary inclusion ensures that the second device receives accurate location information in advance, eliminating the need for subsequent location queries or additional message exchanges.
3Measurement precision
If location information is not included in the answer message, then the message format remains standardized, but emergency services cannot locate the device accurately
Solution Approach 1:
The patent modifies the answer message by adding location information parameters (such as geo-location data or civic address) to the existing SIP response structure. This parameter addition enables precise location information to be conveyed without fundamentally changing the message format, thus achieving location precision while maintaining reasonable message format simplicity.
Data Source
AI summary
A method of conveying a location information (2) representing a physical location of a first communication device (D) from the first communication device (D) to a server (S) comprises sending a first invite message (12) of the server (S), the server (S) being triggered by a third communication device (C), to the first communication device (D) to invite the first communication device (D) to initiate a communication connection (26) to a second communication device (T), and sending an answer message (13) of the first communication device (D) in response to the first invite message (12) to the server (S), wherein the location information (2) is inserted in the answer message (13) for insertion in a second invite message (14) of the server (S) to the second communication device (T) to invite the second communication device (T) to accept the communication connection (26).