SIP Facsimile Apparatus Media Type Switching for Call Handling
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Solution Overview
Problem
Conventional IP-PBX systems fail to accurately determine whether an incoming call is for telephone talk or T.38 facsimile communication, leading to potential failures in ringing status and inappropriate call handling.
Innovation Solution
A facsimile apparatus that uses SIP protocol to transmit an INVITE request with a media type switch from 'audio' to 'image' upon receiving a session establishment request, allowing for appropriate facsimile communication or calling processing based on the response, ensuring correct handling of incoming calls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an IP-PBX starts operating with media type designated as 'audio' for session establishment, then the system can handle both telephone talk and T.38 communication through a unified interface, but the system cannot accurately determine whether the incoming call is for telephone talk or facsimile communication, leading to inappropriate call handling
Solution Approach 1:
The system performs preliminary action by transmitting an INVITE request with media type 'image' before establishing the final communication mode. This allows the system to proactively query the communication partner's capability and intent, receiving a response that indicates whether T.38 facsimile communication or telephone talk should be established, thereby accurately determining the communication type before actual communication begins
Solution Approach 2:
The system uses an intermediary INVITE request exchange as a mediator between the initial 'audio' media type designation and the final communication mode selection. This intermediary step allows both parties to negotiate and confirm the intended communication type without directly committing to either telephone talk or facsimile communication, resolving the ambiguity in determining communication type
2Measurement precision
If the system transmits an INVITE with media type 'image' to determine communication type, then accurate determination of facsimile communication intent is achieved, but additional signaling overhead and communication delay are introduced
Solution Approach 1:
The system performs the media type switching inquiry as a preliminary action during the initial session establishment phase, before actual communication begins. By integrating this capability negotiation into the existing SIP handshake process rather than adding a separate communication phase, the system minimizes the time overhead while still achieving accurate determination of communication type
Solution Approach 2:
The system merges the capability negotiation function with the existing SIP session establishment process. The INVITE request with media type switching is combined with the standard call setup signaling, allowing the system to determine communication type and establish the communication channel in a unified process rather than separate steps, thereby reducing overall time loss
Data Source
AI summary
Provided are a facsimile apparatus, a communication apparatus, and a communication method that perform communication using a session established according to a session initiation protocol (SIP). If an INVITE in which a media type is designated as “audio” is received, an INVITE in which a media type is designated as “image” is transmitted. If a success response is made to the transmitted INVITE, an image session is established and facsimile communication or image communication is executed. If an error response is made to the transmitted INVITE, calling processing for calling an operator is started.