FP4: TMobile & related carriers cannot hear Fairphone user

• /e/ version: 1.5.1-s
• Device model(s): FP4
• Device rooted: no

Summary

Randomly the caller cannot hear the Fairphone user. It seems to also affect the stock see https://forum.fairphone.com/t/cant-hear-caller-unless-on-speaker/93334.

The problem

Steps to reproduce

• Be a T-Mobile or related carrier user
• Make or receive a phone call.

What is the current behavior?

The other caller cannot hear until the Fairphone user switches to the speaker mode.

What is the expected correct behavior?

The other caller can hear the Fairphone user.

Technical informations

Relevant logs (adb logcat)

Relevant screenshots

Solutions

Workaround

Enable/disable the speaker mode or perform a new call.

Possible fixes

@merothh