IMS to CS Multimedia Call Setup via Service Change Fallback
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Solution Overview
Problem
Current technologies fail to establish multimedia calls, particularly video calls, between IP multimedia subsystems (IMS) and circuit-switched (CS) core networks due to the lack of initial media capability information, leading to incorrect call types being established, resulting in unnecessary resource reservation and high charging for users.
Innovation Solution
Implementing a service change and fallback function, such as SCUDIF, to determine and forward media parameters from the receiving party, allowing the network control element to complete the call establishment by selecting the appropriate call mode based on supported services, ensuring multimedia calls can be established even without initial SDP descriptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a call is established from IMS to CS network without initial SDP description, then the call can be set up using basic speech services, but the calling party's media capability information is lost and the call mode cannot be upgraded to multimedia
Solution Approach 1:
The network control element performs preliminary action by determining the calling party's media capability information before completing call establishment. It retrieves this information from the home network or other sources in advance, then uses it to determine the appropriate call mode (speech or multimedia) and modify the receiving party's call mode accordingly, preventing information loss.
2Adaptability or versatility
If the network control element requests media capability information during call establishment, then multimedia calls can be established, but the call setup time increases and the process becomes more complex
Solution Approach 1:
The network control element determines media capability information in advance during the call establishment process, before final call mode selection. This preliminary determination allows the system to prepare the appropriate call mode (speech or multimedia) ahead of time, reducing delays during actual call setup.
Solution Approach 2:
The network control element uses feedback from the receiving party's service change and fallback function response to confirm media capability information. The receiving party responds with its supported services, and the network control element uses this feedback to finalize the call mode determination, ensuring both parties can support the selected mode.
3Ease of manufacture
If the network control element reserves resources for speech calls initially, then resource allocation is simplified, but resources may be over-provisioned if multimedia calls are established
Solution Approach 1:
The network control element dynamically adjusts resource allocation based on determined media capability information. It initially reserves resources for speech calls, then modifies the receiving party's call mode to multimedia if both parties support it, and accordingly adjusts resource provisioning to match the actual call type, avoiding over-provisioning.
Solution Approach 2:
The network control element changes the call mode parameter from speech to multimedia based on determined media capability information. This parameter change triggers corresponding resource allocation adjustments, ensuring resources match the actual service requirements and preventing waste.
4Adaptability or versatility
If the receiving party supports service change and fallback function, then call mode can be modified based on media parameters, but the protocol complexity increases
Solution Approach 1:
The network control element acts as an intermediary that manages the service change and fallback function protocol between the calling and receiving parties. It handles the complexity of call mode modification by processing media capability information, determining appropriate call modes, and coordinating the mode changes, thereby shielding end users from protocol complexity.
Data Source
AI summary
A mechanism for controlling an establishment of a call from a calling party being located in a first communication network environment to a receiving party being located in a second network environment, comprise a determination whether or not information on media parameters supported by the calling party is received in an initialization message for the call, and if the information on media parameters supported by the calling party is not received, a transmission of a specific message based on a service change and fallback function to the receiving party, a receipt, in response to the specific message based on the service change and fallback function, of information on media parameters supported by the receiving party, processing of the information on media parameters supported by the receiving party and a completion of the establishment of the call in correspondence to the media parameters supported by the receiving party and by the calling party.