Acoustic echo cancellation doesn't work on voice calls

• /e/ version: 0.9-2020062560240
• Device model: FP2
• When it started to occur: since always
• Reproducible with the last /e/ version: yes
• Reproducible with LineageOS: don't know

Summary

Using a sip account with the "Phone" app (or sometimes the voice calling function of third party apps) produces a significant (1-2 seconds) echo on the callers side.

• The device is unusable (as sip phone)
• The bug is the source of a data loss or a big waste of time (always preparing a headset)
• The bug concerns a third-party application
• The bug concerns security
• The bug concerns privacy

The problem

Steps to reproduce

1. Configure a SIP account in the "Phone" app.
2. Make a call or receive a call.

What is the current behavior?

The caller or the person on the other side hears its own echo (1-2 seconds delay). In this way it's almost impossible to "communicate".

What is the expected correct behavior?

No echo on the callers side.

Solutions

Workaround

Use a headset.

Possible fixes

The problem is known:

• https://bugtracker.fairphone.com/project/fairphone-android-7/issue/179
• https://bugtracker.fairphone.com/project/fp2-android9/issue/25

And it seems, the FP2 team found a solution for it. They now use the software AEC and disable the hardware AEC or something like that.