Multimedia Session Establishment via Pre-Call Capability Exchange
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Solution Overview
Problem
Current mobile networks, particularly those based on ISUP, face challenges in supporting service changes during multimedia calls, such as transitioning from video to speech calls, due to the requirement for BICC support throughout the core network, which is not feasible with less developed signaling systems like ISUP.
Innovation Solution
Implementing SIP/IMS protocols to enable service changes in ISUP-based mobile CS networks, allowing for capability information exchange between terminals before a call, which includes multimedia call parameters, and using SIP messages for service change requests, thereby bypassing the need for BICC support and enhancing network flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If BICC signaling is used throughout the core network to support service change, then service change capability is improved, but device complexity and network compatibility deteriorate
Solution Approach 1:
The patent segments the service change capability into two parts: IMS domain capability (handled via SIP messages) and CS domain capability (handled via ISUP messages). This segmentation allows each domain to operate independently with its own signaling protocol, avoiding the need for BICC throughout the entire core network while still enabling service change functionality.
Solution Approach 2:
The patent introduces an intermediary mechanism where the terminal itself performs codec negotiation and service change decision-making based on exchanged capability information. This shifts the complexity from the network signaling layer to the terminal layer, allowing ISUP-based networks to support service change without requiring BICC signaling infrastructure.
2Device complexity
If capability information is exchanged during the call (inband negotiation), then call setup is simplified, but call establishment time increases
Solution Approach 1:
The patent implements preliminary capability information exchange between terminals using SIP messages before the actual call is established. The terminals exchange and store codec capabilities and service change support information in advance. When the call is initiated, this pre-exchanged information is reused, eliminating the need for time-consuming inband negotiation during the call setup phase.
3Adaptability or versatility
If ISUP-based networks are used without BICC support, then network compatibility is maintained, but service change functionality is lost
Solution Approach 1:
The patent copies the capability negotiation mechanism from IMS/SIP domain to the CS/ISUP domain. By having terminals exchange capability information via SIP messages before CS call setup, the system replicates the service change functionality available in IMS networks within ISUP-based networks, maintaining compatibility while enabling enhanced functionality.
Data Source
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AI summary
The described method, system and terminals may allow the sending capability information from a first terminal to a second terminal in a capability exchange performed without, or prior to, conducting a call between the first and second terminals. The capability information may include at least one of multimedia call related parameters such as a codec for example, or network capability related information. A session initiation protocol may be used for sending the multimedia call related parameters. A service change may thus rapidly be performed.