IMS Deregistration for Faster Circuit Switched Fallback
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Solution Overview
Problem
In scenarios where the IP Multimedia Subsystem (IMS) experiences frequent timeouts, VoLTE call setup times become excessively long, impacting user experience due to the need for circuit switched fallback procedures, which require substantial time and resources.
Innovation Solution
Implementing a method that utilizes a timeout counter and delay timer to determine when to bypass VoLTE attempts and immediately perform circuit switched fallback procedures, thereby reducing call setup times by deregistering from the IMS and using the CSFB procedure when a threshold of timeouts is reached, ensuring calls are established more efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device attempts VoLTE calls through IMS, then IP-based call functionality is maintained, but call setup time becomes excessively long when IMS is loaded
Solution Approach 1:
The device performs preliminary registration with the IMS network and monitors timeout conditions in advance. When a threshold of timeouts is reached, the device proactively deregisters from IMS before attempting another call, thereby avoiding the time-consuming failed VoLTE call setup process and enabling faster fallback to circuit switched networks.
2Reliability
If the device uses circuit switched fallback procedure, then call establishment is achieved, but the procedure requires substantial time and resources
Solution Approach 1:
The device maintains pre-configured capabilities for both VoLTE and circuit switched calls. When IMS timeout thresholds are reached, the device immediately activates the pre-configured circuit switched fallback procedure without undergoing lengthy registration or setup processes, thereby reducing the time and resources required for call establishment.
3Adaptability or versatility
If the device continuously registers with IMS, then IP-based calling is available, but repeated failures occur when IMS is loaded
Solution Approach 1:
The device implements a feedback mechanism that monitors VoLTE call setup outcomes and timeout conditions. When a threshold of timeouts is detected, the device responds by deregistering from IMS and switching to circuit switched fallback. This feedback-driven adaptation improves call establishment success rate by avoiding repeated failures on a loaded IMS network while preserving the ability to use IP-based calling when conditions are favorable.
Data Source
AI summary
A device, system, and method improve a call setup time. The method is performed at a device configured to establish first and second network connections where the second network performs circuit switched voice calls. The method includes receiving a call input to perform a call and determining whether the device is registered with a first feature to perform the call based on an Internet Protocol (IP). When the device is registered with the first feature, the method includes determining whether timeouts for attempting previous IP calls is greater than a threshold. When the timeouts are at least the threshold, the method includes deregistering from the first feature and performing a circuit switched fallback (CSFB) procedure including a handover from the first network to the second network. The method includes performing the call as a circuit switched call.