When we tested the audio quality of our VoIP App, we found that when the iOS18.0 device was played with AirPods Pro 2, we could hear noises similar to peak clipping and distortion, especially when the sound source played was loud and high-pitched. Here is the device information we tested: Model: iPhone 16 Pro Max, iPhone 15 Pro System version: iOS 18.0 (22A3354) Bluetooth headset model: AirPods Pro 2 Bluetooth firmware version: 6F8 We tested multiple apps (including phone calls, FaceTime, Zoom, WeChat, Tencent Meeting), and they all had the above noise problem. We also found two phenomena: If we use the same iOS 18 device to connect HUAWEI FreeBuds Pro or FreeBuds 2, there is no such noise problem; If we use an iOS 17 device to connect to the same AirPods Pro 2 for testing, there is no such noise problem; Therefore, we suspect that it is caused by the compatibility problem between iOS 18.0 and AirPods firmware 6F8. The firmware version of our AirPods Pro 2 is 6F8, which was released on June 26, and iOS 18.0 was released on September 16. Maybe they are not very compatible. I hope that subsequent firmware updates can fix this problem.

Dear Apple R&D Team, I want to report a bug of CallKit caused by Voicemail in iOS18.0. The following are the header files referenced by our code: #import <CallKit/CXCallObserver.h> #import <CallKit/CXCall.h> Our VoIP app uses the callObserver callback function provided by CXCallObserverDelegate to monitor changes in the system phone status (see the attached picture). The problems we encountered are: Before upgrading to iOS18.0, when we rejected a call, we would receive a callObserver callback, and the status value of hasConnected of CXCall was NO; After upgrading to iOS18.0, when we also rejected a call, the status value of hasConnected of CXCall was YES. So we checked the new features of iOS18.0 and found that it was the influence of the new feature Voicemail. On iOS18.0 devices, if you reject a call, you will enter the Voicemail state by default, which means that I rejected the call, but callObserver told me that the call was connected, which is inconsistent with the user's intuitive experience and will also cause our App to respond incorrectly (cannot resume audio automatically). In fact, the Voicemail function is enabled by default for devices upgraded to iOS 18.0. After I reject a call, I have to wait for the caller to hang up before I can receive callObserver telling me that the call has been hung up. This experience is very bad, because when the caller does not hang up the call, our App cannot sense that I have hung up the call and thinks that I am still on the call, but in fact I did hang up the call. Please refer to the code in the attached picture. According to our understanding, the status should flow like this: When I receive an incoming call, the callObserver callback will trigger, call.hasConnected is NO and call.hasEnded is NO; When I reject the call and switch to Voicemail, the callObserver callback will trigger, call.hasConnected should be NO and call.hasEnded should be YES; When I manually restore the call through Voicemail, the callObserver callback will trigger, call.hasConnected should be YES and call.hasEnded should be NO; When the caller or I finally hang up the call, the callObserver callback will trigger, call.hasConnected is YES, call.hasEnded is YES; However, the current status is as follows: When I receive an incoming call, the callObserver callback will trigger, call.hasConnected is NO and call.hasEnded is NO; When I reject the call and switch to Voicemail, the callObserver callback will trigger, call.hasConnected is YES and call.hasEnded is NO; When I manually restore the call through Voicemail, the callObserver callback will not trigger; Only when the caller finally hangs up, the callObserver callback will trigger, call.hasConnected is YES and call.hasEnded is YES; Our request is very simple. We need to pause audio when a call comes in and resume audio when the call is hung up or rejected. This is our sample code: - (void)callObserver:(CXCallObserver *)callObserver callChanged:(CXCall *)call API_AVAILABLE(ios(10.0)) { bool pause_audio = false; BOOL calling = !call.onHold && !call.hasConnected && !call.hasEnded; BOOL disconnected = !call.onHold && !call.hasConnected && call.hasEnded; BOOL connected = !call.onHold && call.hasConnected && !call.hasEnded; BOOL hang_up = !call.onHold && call.hasConnected && call.hasEnded; if (calling) { xc_log(XC_LOG_INFO, "A phone call is %s", call.outgoing ? "outgoing" : "incoming"); pause_audio = true; } else if (disconnected) { xc_log(XC_LOG_INFO, "An %s phone call has been disconnected", call.outgoing ? "outgoing" : "incoming"); // action of phone call end, resume audio } else if (connected) { xc_log(XC_LOG_INFO, "An %s phone call has just been connected", call.outgoing ? "outgoing" : "incoming"); pause_audio = true; } else if (hang_up) { xc_log(XC_LOG_INFO, "An %s phone call has been hang up", call.outgoing ? "outgoing" : "incoming"); // action of phone call end, resume audio } else { xc_log(XC_LOG_INFO, "Unknown telephony state occured"); } if (pause_audio) { dispatch_async(dispatch_get_main_queue(), ^{ // action of phone call begin, pause audio }); } } I would appreciate any help !!!

I am a developer of Tencent. We found that after AirPods upgraded to the new firmware version 4A400, some AirPods microphones may have abnormal sound problems, especially on the iPhone with the system version iOS 13 . The specific performance is: the sound captured by AirPods microphones will appear intermittently with noise, broken sound, pitch shift, and tremor, and the sense of hearing and intelligibility is poor. Our users have reported that many times when using Tencent Meeting for video calls, the others can’t hear his/her voice, so we tested many iPhones and AirPods and found that they all have some problems. Let’s share our Specific test results: iPhone 11 Pro Max / iOS 13.6.1 / AirPods 2, the sound periodically appears noise and tremor about every 20s, it sounds uncomfortable, and when using the system phone/FaceTime/WeChat call/Zoom test, the effect is the same ； Use the same iPhone as 1 and replace the earphones with AirPods Pro, and the test conditions are exactly the same as 1; Using the same AirPods Pro as 2 and changing the phone to iPhone X / iOS 13.6, there will be occasional discontinuities in the sound, and crackling noises will be heard; Use the same AirPods Pro as 2 and change the phone to iPhone Xs / iOS 13.7. At the beginning, there was continuous noise and pitch shifting. After a few minutes of speaking, it returned to normal, and then the sound remained normal; Using the same AirPods Pro as 2 and changing the phone to iPhone 12 Pro Max / iOS 15.0.2, the sound is completely normal. Why does the same AirPods, on different iPhones, have such different performance of the collected sound quality, and the same phenomenon of using various VoIP apps, and all of them have problems on iOS 13? Does the 4A400 firmware have compatibility issues with the iOS 13 system? We noticed that the previous AirPods hardware sampling rate was 16kHz, but after upgrading to 4A400, the hardware sampling rate changed to 24kHz. Is the above noise related to the change of the hardware sampling rate? Do I need to modify the Audio Unit parameters to solve the above problems? Our app has a very large group of personal and corporate users. When they find that there is a problem with the sound, they will give us feedback, which brings us more pressure. Hope to get a reply from Apple or other developers, thank you!