Bug 256593 – [MacOS] All Users can hear each other if MacOS User accepts an incoming PSTN call that is received on iPhone while MacOS User is in WebRTC call

• Status: NEW
• Component: WebRTC

[Madara Freimane]

Summary:
[MacOS] All Users can hear each other if MacOS User accepts an incoming PSTN call that is received on iPhone while MacOS User is in WebRTC call

Tested devices:
A bug is reproducible on:
- MacBook Pro (Intel, 2020, MacOS 13.3.1 (a)) with Safari (V16.4) AND iPhone 13 (iOS 16.4.1(a))
- MacBook Pro (M1, 2020, MacOS 13.3.1 (a)) with Safari (V16.4) AND iPhone 14 Pro Max (iOS 16.4.1(a))

Use case:
Precondition:
iPhone and MacBook devices are under the same iCloud account (to be able to get "iPhone microphone" as a microphone device under the settings in WebRTC call)
The MacOS User is in an active audio call

Steps:
1. Another User makes a PSTN call to iPhone User
2. MacOS accepts the incoming PSTN call that is received on MacOS because MacBook is connected to iPhone (same iCloud account is used)

Actual result:
All Users can hear each other if MacOS User accepts an incoming PSTN call that is received on iPhone while MacOS User is in a WebRTC call (The user who made a call to iPhone User can hear audio that comes from the WebRTC call, and the Users who are in the WebRTC call can hear audio between Users who are in the PSTN call)

Expected result:
Audio is available only from one active call:
- when the PSTN call is active and accepted by MacOS User, the WebRTC call is muted and Users are not able to hear each other

Reproducibility:
100%

Additional information:
- Sysdiagnostics file added from MacBook device (bug reproduced at 19:37 pm, 10.05.2023., EET):
https://drive.google.com/file/d/1nnlgLr4Pd5VluF8xhPiigdclnCF2-2Dc/view?usp=sharing

[Radar WebKit Bug Importer]

<rdar://problem/109233126>

[Madara Freimane]

Bug is still reproducible.

Tested devices and browsers:
- MacBook Pro (M1, 2020, macOS Sonoma 14.4) and Safari (V17.4 (19618.1.15.11.12)) AND iPhone 11 Pro Max (iOS 17.4, build: 21E219)

New sysdiagnostics file available:
https://drive.google.com/file/d/12ULFx0B3SCFD7biJSVqxusA6KFeElPBn/view?usp=sharing

Bug is no longer reproducible

Tested devices:
- macOS 14 + iOS 17: MacBook Pro (i5, 2020, macOS 14.6) and Safari 17.6 (19618.3.11.11.5) + iPhone 15 Plus (iOS 17.5.1)
- macOS 15 + iOS 18: MacBook Pro (M1, 2020, macOS 15.7) and Safari 18.6 (20621.3.11.11.3) + iPhone 13 mini (iOS 18.6.2)
- macOS 26 + iOS 26: MacBook Pro (M1, 2020, macOS 26.0) and Safari 26.0 (21622.1.22.11.14) + iPhone 14 (iOS 26.0)

Recap:
macOS user and WebRTC user are in an active WebRTC call. macOS user answers an incoming PSTN call to the connected iPhone
PSTN caller does not hear the WebRTC user, and the WebRTC user does not hear the PSTN caller. However, the macOS user can hear and be heard in both calls (PSTN and WebRTC) at the same time

A separate WebKit bug already exists for the audio overlap between two calls for macOS: https://bugs.webkit.org/show_bug.cgi?id=255986 (still open and repro in Sep 2025)

This WebKit bug can be closed