Teracube 2e: Bluetooth headphone ringtone silent after Android 15 upgrade

/e/OS Devices Teracube
1

Device: Teracube 2e
OS version: /e/OS 3.5 (3.5-a15-20260211580868-official-emerald)
Headphones: Sony WH-1000XM4

Issue

Since upgrading to /e/OS 3.4 (Android 15), incoming phone calls no longer produce a ringtone through my Bluetooth headphones. The phone speaker rings normally. Before the upgrade (Android 12), the headphones would play a ringtone — different from the phone’s, but audibly present. Now on the latest version.

Also tried headphone upgrade via Sony’s app (3.0.1), but haven’t solved the problem. No relevant settings found in Sony’s Sound Connect app.

What still works

  • The call itself routes correctly through the headphones (voice both ways)

  • The headphones respond to the incoming call event: noise cancelling is disabled when a call comes in, confirming the HFP handshake is happening

What’s broken

  • No ringtone audio is played through the headphones — only the phone speaker rings

Additional context

  • I use custom ringtones (one default, two assigned to specific contacts), all files on my phone’s storage.

  • Bluetooth media audio (A2DP) works fine; codec set to AAC

  • Both “Phone calls” and “Media audio” are enabled in the device’s Bluetooth settings

  • Ring volume is not muted

  • Not rooted, so no build.prop edits possible

Suspected cause (after consulting with AI)

The HFP connection is clearly being triggered (NC switching proves this), but the ringtone audio stream appears to stay on the phone speaker rather than routing over HFP. This may be related to how Android 13+ changed STREAM_RING audio routing behavior, possibly not fully accounted for in the /e/OS 3.x builds for this device.

Has anyone else experienced this or found a workaround?

Cheers,
Ervin

2

This has always been the case on my FP3: ring and notification tones do always come in the device speaker regardless of any Bluetooth. When you have noise cancelling headphones you hear almost nothing. In many cases you tend then to take the headphones down, what was there?, and then you can hear the ringtone. It gets then interesting when it was indeed a phone call - the voice of the other one is then again in the headphone! - This concept is so creepy but it’s as old as my device.