Hi @DTS Engineer, We’re able to reproduce this issue on a specific iOS device. Could you please take a look at the comment from @rc-yorick_zheng?

Hi @DTS Engineer Thank you for your response and insights. We understand your point about AVAudioSession possibly being activated too early by third-party libraries like WebRTC. However, we would like to clarify that our app does not call AVAudioSession.setActive(true) before CallKit triggers didActivate, and we've ensured that WebRTC is initialized only after this delegate method is called. We've also double-checked and confirmed that there is no early activation of the audio session before CallKit is expected to activate it. Despite this, on iOS 18.4.1, we’re seeing a statistically significant increase in the failure rate of didActivate, as shown in our metrics. Given that our app version remains unchanged, and the issue correlates strongly with the iOS 18.4.1 system update, could you help us further investigate whether there might be behavior changes in AVAudioSession or CallKit that could explain this? Any guidance or diagnostic suggestions would be greatly appreciated?