Microsoft Teams high-pitched voices

Not sure if I should post this here, as I’m faily sure this is an issue with MS Teams. But I would like to find FP4 users who have the same problem, to see if someone has a fix.

I have a Fairphone 4 with the latest stable /e/ on it. I’ve installed MS Teams for work. Whenever I make a call, everyone’s voice is high-pitched, as in the kind of effect you get when you speed up a clip, or when you inhale helium. It’s such a strange bug. No other app suffers from this behaviour. Phone, telegram, whatsapp calls: they’re all completely fine.

Has anyone else encountered this bug, and can you share how (if) you fixed it?

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Maybe this helps you to investigate or haxtibal can investigate further

https://forum.fairphone.com/t/microphone-quality-of-the-fp4-when-using-signal-low-volume/79021/18?u=yvmuell

Has anyone else encountered this bug

Not on FP4. But I’ve seen and debugged such a high-pitch effect for VoIP calls in between an AVM Fritz!Box and an internet provider. These calls use SDP to negotiate the session, and RTP to stream audio, where audio itself is encoded using codecs like ITU-T G.722 or ITU-T G.711. The codec determines the sampling rate. What happened was, during SDP Invite sender and receiver failed to agree which codec they would use. The sender started an RTP stream using 8 kHz codec, while the receiving side thought it must be an 16 kHz codec and therefore played back the incoming samples at the doubled rate. The result was high pitched and patchy sound.

Not sure how much this is applicable for MS Teams calls. But I wouldn’t be surprised if they just use the same protocols. SIP and RTP are pretty much the standard for anything phone call like over the internet.

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Thanks for your in-depth reply. So in your example, it sounds like the Fritz!box was the culprit. Could the same apply to my situation?

You’d think the app and the server know which protocols to use :thinking:. Do you think it would make a difference to call over 5G instead of wifi? Or to have stock Android instead of /e/ installed?

So in your example, it sounds like the Fritz!box was the culprit.

In the end it was fixed by switching internet providers, and a temporary solution was to enforce a lower quality codec by configuration. I believe the Fritz!Box could have handled the handshake better, but AVM disagreed, and RFC 4566 is not clear enough to definitely tell who was to blame in that situation.

You’d think the app and the server know which protocols to use

Don’t know too much about MS Teams. From docs.microsoft.com it seems they’re actually using SIP and RTP. In SIP/SDP, codec negotiation goes roughly like this: Participant 1: “I support codec a, b, c and prefer c”. Participant 2: “I support codec a, x, y and prefer a”. Each participant can then decide on its own (following rules described in RFC 4566) which codec to use and starts to send its tx RTP stream.

Supported codecs are device-hardware/software specific. A preferred codec can often be configured, maybe teams has such a setting?

Do you think it would make a difference to call over 5G instead of wifi? Or to have stock Android instead of /e/ installed?

Guess both could make a difference, but actually don’t know, sorry. 5G instead of wifi is easy to try. Don’t know how simple a switch to stock Android would be for you. If not too simple, I could give MS teams a try on my phone. Not today, it’s late already :slight_smile:

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Hi, same issue here on a fairphone 4 with /e/os. I would be curious to know how to fix this, as there does not seem to have any configuration options with teams on mobile.

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Sorry to hear that, but I’m glad I’m not the only one :wink:

Have you tried the option of calling over mobile network instead of wifi? I haven’t had the chance to test it.

Nice idea, but it did not make a change. I just tested while forbidding access to WiFi, and the same happens.

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