I’m seeing a Bluetooth call audio routing issue on a new iPhone 17 Pro running iOS 26.5.1, build 23F81.
Bluetooth media audio works normally. Music and video audio stay on Bluetooth headphones without issues. The problem appears only when the device switches into call audio / HFP mode.
Tested with multiple earbuds: Samsung, OPPO, Huawei and CMF Buds Pro 2. The behavior is similar with all of them. There are no other Bluetooth devices connected. Call Audio Routing is already set to Bluetooth Headset in Accessibility settings.
The issue affects cellular calls, FaceTime Audio, Telegram and Signal. In some cases the earbuds seem to switch into call mode, but the call audio route falls back to the iPhone receiver or speaker instead of staying on the Bluetooth headset. After the call ends, Bluetooth media audio returns normally.
I captured a sysdiagnose right after reproducing the issue.
Relevant observations from the logs:
- Device: iPhone18,2
- iOS: 26.5.1
- Build: 23F81
- Sysdiagnose time: 2026-06-03 11:22:03 +0300
- In Bluetooth/CoreCapture/bluetooth_status.txt, Bluetooth was ON
- 3 paired devices were present
- 1 device was connected
- Connected device at the time: CMF Buds Pro 2
So the headset was not simply disconnected from the phone.
In the powerlog, before the call the audio route was HeadphonesBT for media playback. Around the FaceTime Audio test, HeadsetBT / PhoneCall appeared, but then the route moved to ReceiverAndMicrophone / Speaker instead of staying on HeadsetBT. During a later cellular call, the active PhoneCall route was also ReceiverAndMicrophone rather than HeadsetBT. After the call ended, the route returned to HeadphonesBT for media playback.
This looks like the Bluetooth connection remains alive, but call audio / HFP routing fails.
The same sysdiagnose also contains CentauriFirmwareEvent entries under crashes_and_spins from the previous day. They show:
- subsystem = BT
- host-reason = firmware crash
- BTMAIN panic
- faulting_task = link_manager_thread
- LMAC_5G watchdog expired
- SCAN watchdog expired
These firmware crash events do not happen at the exact same timestamp as the call test, so I’m not claiming that every call directly crashes Bluetooth firmware. But the sysdiagnose shows both incorrect Bluetooth call audio routing and separate BT firmware crash events.
Has anyone seen similar behavior on iPhone 17 / iOS 26 with Bluetooth HFP call audio? Could this be a known iOS 26 / Apple N1 / Bluetooth firmware issue, or does it look more like a hardware defect of this particular device?